***************************************************************************
***************************************************************************



The UCR Standard Library for Assembly Language Programmers,
Written By Randall Hyde and others, is

sssssss ss ss ss sssssss sssssss
ss ss ss ssss ss ss ss
ss ss ss ss ss ss ss ss
sssssss sssssssss ssssssss sssssss sssss ssssssss
ss ss ss ss ss ss ss ss
ss ss ss ss ss ss ss ss
sssssss ss ss ss ss ss ss sssssss



ww ww ww sssssss sssssss
ww ww wwww ss ss ss
ww ww ww ww ww ss ss ss
ww wwww ww wwwwwwww sssssss sssss
ww ww ww ww ww ww ss ss ss
wwww wwww ww ww ss ss ss
ww ww ww ww ss ss sssssss




We do not want any registration fees for this software.

Now for the catch... It is more blessed to give than to receive.
If this software saves you time and effort and you enjoy using it,
our lives will be enriched knowing that others have appreciated our work.
We would like to share this wonderful feeling with you. If you like this
software and use it, we would like you to contribute at least one routine to
the library. Perhaps you think this library has some neat-o routines in it.
Imagine how nice it would become if everyone used their imagination to
contribute something useful to it.

We hereby release this software to the public domain. You can use it in any
way you see fit. However, we would appreciate it if you share this software
with others as much as it has been shared it with you. That is not to suggest
that you give away software you have written with this package (We're not
quite as crazy as Richard Stallman, bless his heart), but if someone else would
like a copy of this library, please help them out. Naturally, we would be
tickeled pink to receive credit in software that uses these routines (which is
the honorable thing to do) but we understand the way many corporations operate
and won't be terribly put off if you use it without giving due credit.

Enjoy!

If you have comments, bug reports, new code to contribute, etc., you can
reach us through:

rhyde(On BIX).
[email protected](On Internet).
[email protected]

or

Randall Hyde
Dept of Computer Science
122 University Office Bldg
University of California
Riverside, Ca. 92521


COMMENTS ABOUT THE CODE:
************************

Please don't expect super optimal code here. Most of it is fairly mediocre
(from a size/speed point of view). Hopefully, you'll agree, it's the idea
that counts. If you do not like something I have done, you have got the
sources -- have at it. (Of course, it would be appreciated if you would
send any modifications to one of the E-MAIL addresses above.)


****************+******************** NOTE ************************************

Please understand the purpose of this code! This library is here to make
assembly language programming easy. The nature of this library encourages
people to write code in a fashion similar to that employed when they write
programs in a high level language like C. While this familiar style of
programming does make the task easier, it is not the most appropriate
approach to use when flat-out performance is what you're seeking. "C code
written with MOV instructions" is never as fast as pure assembly language
code employing the proper programming paradigm. Why mention this? Well,
some readers may have heard about assembly language's legendary performance
and they're expecting to achieve that using this library. While programs
written with this library may very well run faster than a comparable program

written in a HLL, you will not get fantastic performance improvement until
you stop thinking in HLLs and starting "thinking" in assembly. The purpose
of this library is to help you *avoid* thinking in assembly language. There-
fore, this code will not help you achieve those fantastic performance levels
you've been hearing about; indeed, this library may stand in the way of that
goal. It's not that these routines are terribly slow, mind you. They just
encourage an inappropriate programming style if speed is what you're after.

On the other hand, since only 10-20% of the code of any given program
represents the time critical stuff (an argument long employed by HLL
supporters), there is nothing wrong with judicious use of this code within
a program that has to be fast. As usual, if performance is your primary
goal, you must study the problem and the program you generate very carefully
to isolate the time critical portions. If you are interested in high-
performance programming at the "micro-algorithm" level, you should take a look
at Michael Abrash's text "Zen of Assembly." This excellent book will explain
many ways to improve the performance of your code at the sub-algorithm level
(where assembly language really shines).



COMMENTS ABOUT THIS DOCUMENTATION:
**********************************

You will have to forgive us for the inconsistent style appearing throughout
this document. Keep in mind that this document has been prepared by many
different people. Keeping the styles consistent is a time consuming and
difficult task.

Whenever a routine's description claims that the flags are not affected,
you should not interpret this to mean that the routine preserves the flags.
Most routines do *not* preserve any of the flags. Such a statement simply
means that the routine does not *explicitly* return a value in one (or more)
of the flag bits.

Note that proper credit has been given to the author of each of the various
routines appearing in this library *except* for those written by Randall
Hyde. All routines without an author by-line were probably written by
Randall Hyde (unless we screwed up somewhere and forgot to put a name
in the documentation). Most of these routines were tested and documented
by various students in Randy Hyde's CS 13 (assembly language) and CS 191X /
CS 185 courses (Commercial Software Development). There are too many names
to mention here, but these students definitely deserve the credit for locating
numerous bugs in the code, providing many suggestions, and doing other work.

Of course, there have been numerous suggestions and bug notices from helpful
souls on BIX and the Internet, as well. Thank you all.


=============================================================================

Version History:

Version 00- Initial release as "Randy Hyde's Standard Library for 80x86
Assembly Language programmers"

Version 10-Initial release as "UCR Standard Library..." CS 191X
students did some testing and documentation in this release.

Version 20-More testing on several routines. Added floating point
library and several other routines.

Version 21-Fixed *MAJOR* bugs in floating point package. Added
11-1-91several new routines. Included new "TEST" files with
the library. Also included SHELL.ASM file inadvertently
left out of Version 2.0.

Version 22-Made some minor modifications to puth, putl, ltoa, and htoa
11-14-91as per suggestions made by David Holm and Terje Maithesen

Version 23-Made a small but *major* modification to the stdlib.a and
11-22-91stdlib.a6 files to force library calls into the STDGRP group.
Otherwise the linker substitued bad segment addresses for
the far calls to the library routines. A real problem when
accessing variables in StdData.

Version 24-Yet more changes to fix the stupid MASM group/segment:offset
12-7-91bug. Made various changes to the STDLIB.A file. Also fixed
a problem in the FP routines- forgot to declare sl_sefpa
public. Finally, created batch file to automatically unpack
everything from DOS (assuming presence of PKUNZIP somewhere
in the current path).

Version 25-Some new macros (DOS, ExitPgm), fixed a problem with the
12-25-91PUTI routine, added some SmartArray items. Also added the
GetEnv routine.

Version 26-Maintenance release coinciding with the Dr. Dobb's article
2/20/92in the March 1992 issue.

Version 27-SmartLists and interrupt driven serial routines added to
6/19/92the libraries. Also created smaller include files for
each of the standard library categories. (note: the serial
routines actually existed prior to this release, they were
cleaned up and documented for this release). Fixed a couple
of truly disgusting bugs in the floating point package
(wouldn't properly print values like 8100 and hung whenever
encountering a zero value in FADD/FSUB).


==============================================================================


ROUTINES WE WOULD LIKE TO HAVE:
*******************************

If you're interested in adding some routines to this
package, GREAT! Here are some suggestions.

1) Routines which manipulate directories (read/write/etc.)
2) A regular expression interpreter.
3) Length-prefixed strings package.
4) A graphics package.
5) An object-oriented programming class library.
6) Floating point functions (e.g., SIN, COS, etc.)
7) Just about anything else appearing in a HLL "standard" library.
If you've got any ideas, we would love to discuss them with you. The best
way to reach us is through the E-MAIL addresses above.


MISSING ROUTINES TO BE SUPPLIED IN THE FUTURE:
**********************************************

Character strings:
trim-Removes trailing blanks from a string.
blkdel-Removes leading blanks from a string.
translit-Transliterates characters in a string based on a translation
table.


Pattern matching and character sets:
span-Skips through a sequence of characters in a string which
belong to a character set.
break-Skips through a sequence of characters in a string which do not
belong to a character set.
any-Skips over a character if it is a member of a set.
notany-Skips over a character in a string if it is not a member
of a set.
skip-Skips "n" characters in the string.
tab-Matches up to the nth character in a string.
rtab-Matches up to the nth character from the end of a string.
pos-Matches if we are currently at the nth position in a string.
rpos-Matches if we are at the nth position from the end of the
string.
mark-Marks a position in a string during pattern matching
grab-Copies everything from the last mark and creates a new string
on the stack from this substring.
match-Initialize pattern matching system.
alternate-Try an alternative if the current pattern does not match.
arb-Skip over an arbitrary number of characters in a match.
replace-Replace a substring from the last mark to the current
position with some other string.
fail-Force a match failure.
succeed-Force a match success.


Memory Manager Package
Memavail-Largest block of free memory available on the heap.
Memfree-Total amount of free space on the heap.
BlockSize-Returns the size of the memory block which es:di points at.


Process Manager Package
CoCall-Call a coroutine.
CoInit-Initialize a coroutine.
CoRet-Quit a coroutine.


HOW TO USE THE STANDARD LIBRARY:
********************************

When you are ready to begin programming with the library, you should
copy the shell.asm file, provided in the package, to another file in
which you will be working, i.e. myprog.asm. The shell.asm file sets
up the machine (segments, etc.) as the UCR Standard Library expects
them. Results are undefined for other setups. Therefore, I strongly
suggest, that when you begin using these routines, you follow the
shell.asm format. Later, when you are familiar with the software,
you may wish to create your own shell.asm file, but it is wise to
initially use the one provided. The shell.asm file has comments which
tell you where to place your code, variables, etc.

There is an include file stdlib.a which
you should include in every assembly you perform which calls the stdlib
routines. SHELL.ASM already includes this file. *YOU MUST PLACE THE
INCLUDE STATEMENT OUTSIDE OF ANY SEGMENTS IN YOUR PROGRAM*. Preferably
as the first line of your program (just like SHELL.ASM). If you place
this include directive inside a segment, certain assemblers/linkers
(especially MASM) will not properly assemble and link your programs.
They will assemble and link without error, but the resulting program
will not execute correctly.

The STDLIB.A file contains macros you can use to call each of the routines
in the standard library. For example, to call PRINTF you would use the
statement
printf
db"format string",0
dbother,vars

rather than "calling" printf. Printf is actually a macro, you cannot call
it directly (all of the standard library routines have names like "sl_printf"
and the macro issues a call to the appropriate routine). These macros have
two main purposes-- first, the differentiate calls to the standard library
routines (i.e., no "call" instruction is the difference); and second, they
contain some extra code to perform "smart linking" with MASM 5.1 & earlier,
TASM, and OPTASM. MASM 6.0 supports a new directive, extrndef, which
eliminates the need for this extra code, but the extra code works nonetheless.

Starting with version 27, many of the standard library macros were separated
into smaller files. This speeds up assembly when you don't need *all* of
the routines in the library (the macro file is getting quite large).
STDLIB.A still exists and still loads everything, but you should get in the
habit of specifying the smaller files instead.


All of the standard library routines, and most of their local data values,
are in a segment named "stdlib". You should not create such a segment unless
you plan on adding new routines to the standard library.


HOW THE STANDARD LIBRARY IS ORGANIZED:
**************************************

In the next several pages are the documentation spec sheets for each of the
standard library routines. The routines are listed by category. The listing
of the categories and their order in the documentation is below.

Standard Input Routines
Standard Output Routines
Conversion Routines
Utility Routines
String Handling Routines
Memory Management Routines
Character Set Routines
Floating Point Routines
File I/O
Miscellaneous Routines
Smart List Routines
Serial Port I/O

In addition, at the beginning of each of the category is a brief
discussion of the purpose of its routines.





Standard Input Routines:
Character Input Routines
------------------------


The character input routines take input from either a standard
device (keyboard, etc.) or a standard library. After the character input
routines receive the characters they either place the characters on the stack
and/or return. The character input routines work similar to the "C" character
input routines.



Routine: Getc
--------------


Category: Character Input Routine


Registers on Entry: None


Registers on Return: AL- Character from input device.
AH- 0 if eof, 1 if not eof.


Flags Affected: Carry- 0 if no error, 1 if error. If error occurs, AX
contains DOS error code.


Example of Usage:
getc
mov KbdChar, al
putc


Description: This routine reads a character from the standard input device.
This call is synchronous, that is, it does not return until a
character is available. The Default input device is DOS
standard input.

Getc returns two types of values: extended ASCII (codes 1-255)
and IBM keyboard scan codes. If Getc returns a non-zero value,
you may interpret this value as an ASCII character. If Getc
returns zero, you must call Getc again to get the actual
keypress.

The second call returns an IBM PC keyboard scan code.

Since the user may redirect input from the DOS command line,
there is the possibility of encountering end-of-file (eof)
when calling getc. Getc uses the AH register to return eof
status. AH contains the number of characters actually read
from the standard input device. If it returns one, then
you've got a valid character. If it returns zero, you've
reached end of file. Note that pressing control-z forces an
end of file condition when reading data from the keyboard.

This routine returns the carry flag clear if the operation
was successful. It returns the carry flag set if some sort
of error occurred while reading the character. Note that eof
is not an error condition. Upon reaching the end of file,
Getc returns with the carry flag clear. If getc is seen from
a file the control-z is not seen as an end-of-file marker,
but just read in as a character of the file.

Control-c if read from a keyboard device aborts the program.
However if when reading something other than a keyboard
(files, serial ports), control-c from the input source
returns control-c. However when pressing control-break
the program will abort regardless of the input source.

Regarding CR/LF, if the input is from a device, (eg. keyboard
serial port) getc returns whatever that device driver returns,
(generally CR without a LF). However if the input is from
a file, getc stripes a single LF if it immediately follows
the CR.

When using getc files operate in "cooked" mode. While
devices operate in "pseudo-cooked" mode, which means no
buffering, no CR -> CR/LF, but it handles control-c, and
control-z.

See the sources for more information about GETC's internal
operation.

Include:stdlib.a or stdin.a




Routine: GetcStdIn
--------------------


Category: Character Input Routine

Register on entry: None.

Register on return: AL- Character from input device.

Flags affected: AH- 0 if eof, 1 if not eof.
Carry- 0 if no error, 1 if error
(AX contains DOS error code if error occurs).


Example of Usage:
GetcStdIn
mov InputChr, al
putc


Description: This routine reads a character from the DOS standard input
device. This call is synchronous, that is, it does not return
until a character is available. See the description of Getc
above for more details.

The difference between Getc and GetcStdIn is that your
program can redirect Getc using other calls in this library.
GetcStdIn calls DOS directly without going through this
redirection mechanism.


Include:stdlib.a or stdin.a






Routine: GetcBIOS
-------------------


Category: Character Input Routine

Register on entry: None

Register on return: AL- Character from the keyboard.

Flags affected: AH- 1 (always). Carry- 0 (always).

Example of Usage:
GetcBIOS
mov CharRead, al
putc


Description: This routine reads a character from the keyboard. This call is
synchronous, that is it does not return until a character is
available.

Note that there is no special character processing. This
code does *not* check for EOF, control-C, or anything
else like that.



Include:stdlib.a or stdin.a



Routine: SetInAdrs
-------------------

Category: Character Input Routine

Registers on Entry: ES:DI - address of new input routine

Registers on return: None

Flags affected:

Examples of Usage:

mov es, seg NewInputRoutine
mov di, offset NewInputRoutine
SetInAdrs



les di, RoutinePtr
SetInAdrs


Description: This routine redirects the stdlib standard input so that it
calls the routine who's address you pass in es:di. The
routine (whose address appears in es:di) should be a "getc"
routine which reads a character from somewhere and returns
that character in AL. It should also return EOF status in
the AH register and error status in the carry flag (see
the description of GETC for more details).


Include: stdlib.a or stdin.a





Routine: GetInAdrs
--------------------

Category: Character Input Routine

Register on entry: None

Register on return: ES:DI - address of current input routine (called by Getc).

Flags affected: None


Example of Usage:
GetInAdrs
mov word ptr SaveInAdrs, di
mov word ptr SaveInAdrs+2, es


Description: You can use this function to get the address of the current
input routine, perhaps so you can save it or see if it is
currently pointing at some particular piece of code.
If you want to temporarily redirect the input and then restore
the original input or outline, consider using
PushInAdrs/PopInAdrs described later.


Include:stdlib.a or stdin.a



Routine: PushInAdrs
---------------------

Category: Character Input Routine

Register on entry: ES:DI - Address of new input routine.

Register on return: Carry=0 if operation successful.
Carry=1 if there were already 16 items on the stack.

Example of Usage:
mov es, seg NewInputRoutine
mov di, offset NewInputRoutine
PushInAdrs
.
.
.
les di, RoutinePtr
PushInAdrs


Description: This routine "pushes" the current input address onto an
internal stack and then copies the value in es:di into the
current input routine pointer. The PushInAdrs and PopInAdrs
routines let you easily save and redirect the standard output
and then restore the original output routine address later on.
If you attempt to push more than 16 items on the stack,
PushInAdrs will ignore your request and return with the
carry flag set. If PushInAdrs is successful, it will
return with the carry flag clear.


Include:stdlib.a or stdin.a





Routine: PopInAdrs
--------------------

Category: Character Input Routine

Register on entry: None

Register on return: ES:DI - Points at the previous stdout routine before
the pop.

Example of Usage:
mov es, seg NewInRoutine
mov di, offset NewInputRoutine
PushInAdrs
.
.
.
PopInAdrs


Description: PopInAdrs undoes the effects of PushInAdrs. It pops an item
off the internal stack and stores it into the input routine
pointer. The previous value in the output pointer is returned
in es:di.

Include:stdlib.a or stdin.a





Routine: Gets, Getsm
---------------------

Category: Character Input Routine

Register on entry: ES:DI- Pointer to input buffer (gets only).

Register on return: ES:DI - address of input of text.
carry- 0 if no error, 1 if error.
If error, AX contains: 0- End of
file encountered in middle of
string. 1- Memory allocation error (getsm only).
Other- DOS error code.


Flags affected: None

Example of usage:
getsm ;Read a string from the
;keyboard
puts ;Print it
putcr ;Print a new line
free ;Deallocate storage for
;string.

movdi, seg buffer
moves, di
leadi, buffer
gets
puts
putcr


Description: Reads a line of text from the stdlib standard input device.
You must pass a pointer to the recipient buffer in es:di to
the GETS routine. GETSM automatically allocates storage for
the string on the heap (up to 256 bytes) and returns a pointer
to this block in es:di.

Gets(m) returns all characters typed by the user except for the
carriage return (ENTER) key code. These routines return a
zero-terminated string (with es:di pointing at the string).
Exactly how Gets(m) treats the incoming data depends upon
the source device, however, you can usually count on Gets(m)
properly handling backspace (erases previous character),
escape (erase entire line), and ENTER (accept current line).

Other keys may affect Gets(m) as well. For example, Gets(m),
by default, calls Getc which, in turn, usually calls DOS'
standard input routine. If you type control-C or break while
read from DOS' standard input it may abort the program.

If an error occurs during input (e.g., EOF encountered in
the middle of a line) Gets(m) returns the error code in
AX. If no error occurs, Gets(m) preserves AX.

Include: stdlib.a or stdin.a





Routine: Scanf
---------------

Category: Character Input Routine

Register on entry: None

Register on return: None

Flags affected: None

Example of usage:
scanf
db "%i %h %^s",0
dd i, x, sptr

Description: * Formatted input from stdlib standard input.
* Similar to C's scanf routine.
* Converts ASCII to integer, unsigned, character, string, hex,
and long values of the above.
Scanf provides formatted input in a fashion analogous to
printf's output facilities. Actually, it turns out that scanf
is considerably less useful than printf because it doesn't
provide reasonable error checking facilities (neither does C's
version of this routine). But for quick and dirty programs
whose input can be controlled in a rigid fashion (or if you're
willing to live by "garbage in, garbage out") scanf provides
a convenient way to get input from the user. Like printf, the
scanf routine expects you to follow the call with a format
string and then a list of (far pointer) memory addresses. The
items in the scanf format string take the following form: %^f,
where f represents d, i, x, h, u, c, x, ld, li, lx, or lu.
Like printf, the "^" symbol tells scanf that the address
following the format string is the address of a (far) pointer
to the data rather than the address of the data location itself.
By default, scanf automatically skips any leading whitespace
before attempting to read a numeric value. You can instruct
scanf to skip other characters by placing that character in the
format string. For example, the following call instructs scanf
to read three integers separated by commas (and/or whitespace):

scanf
db "%i,%i,%i",0
dd i1,i2,i3

Whenever scanf encounters a non-blank character in the format
string, it will skip that character (including multiple
occurrences of that character) if it appears next in the input
stream. Scanf always calls gets to read a new line of text
from stdlib's standard input. If scanf exhausts the format
list, it ignores any remaining characters on the line. If
scanf exhausts the input line before processing all of the
format items, it leaves the remaining variables unchanged.
Scanf always deallocates the storage allocated by gets.


Include: stdlib.a or stdin.a




Character Output Routines
-------------------------


The stdlib character output routines allow you to print to the
standard output device. Although the processing of non-ASCII
characters is undefined, most output devices handle these characters
properly. In particular, they can handle return, line feed, back space,
and tab.

Most of the output routines in the standard library output data
through the Putc routine. They generally use the AX register upon
entry and print the character(s) to the standard output device by
calling DOS by default. The output is redirectable to the
user-written routine. However, the PutcBIOS routine prints doesn't
use DOS. Instead it uses BIOS routines to print the character in AL
using the INT command for teletype-like output.

The print routines are similar to those in C, however, they differ
in their implementation. The print routine returns to the address
immediately following the terminating byte, therefore, it is important
to remember to terminate your string with zero or you will print an
unexpected sequence of characters.



Routine: Putc
--------------

Category: Character Output Routine

Registers on Entry: AL- character to output

Registers on Return: None

Flags affected: None

Example of Usage:
mov al, 'C'
putc ;Prints "C" to std output.


Description: Putc is the primitive character output routine. Most other
output routines in the standard library output data through
this procedure. It prints the ASCII character in AL register.
The processing of control codes is undefined although most output
routines this routine links to should be able to handle return,
line feed, back space, and tab. By default, this routine calls
DOS to print the character to the standard output device. The
output is redirectable to to user-written routine.


Include: stdlib.a or stdout.a



Routine: PutCR
---------------

Category: Character Output Routine

Register on entry: None

Register on return: None

Flags affected: None

Example of Usage: PutCR


Description: Using PutCR is an easy way of printing a newline to the stdlib
standard output. It prints a newline (carriage return/line feed)
to the current standard output device.


Include: stdlib.a or stdout.a


Routine: PutcStdOut
-------------------

Category: Character Output Routine

Registers on Entry: AL- character to output

Registers on Return: None

Flags Affected: None

Example of Usage:
mov AL, 'C'
PutcStdOut ; Writes "C" to standard output


Description: PutcStdOut calls DOS to print the character in AL to the standard
output device. Although processing of non-ASCII characters and
control characters is undefined, most output devices handle these
characters properly. In particular, most output devices properly
handle return, line feed, back space, and tab. The output is
redirectable via DOS I/O redirection.


Include: stdlib.a or stdout.a



Routine: PutcBIOS
-----------------

Category: Character Output Routine

Registers on Entry: AL- character to print

Registers on Return: None

Flags Affected: None

Example of Usage:
mov AL, "C"
PutcBIOS


Description: PutcBIOS prints the character in AL using the BIOS routines,
using INT 10H/AH=14 for teletype-like output. Output through
this routine cannot be redirected; such output is always sent
to the video display on the PC (unless, of course, someone has
patched INT 10h). Handles return, line feed, back space, and
tab. Prints other control characters using the IBM Character
set.


Include: stdlib.a or stdout.a



Routine: GetOutAdrs
-------------------

Category: Character Output Routine

Registers on Entry: None

Registers on Return: ES:DI- address of current output routine (called by Putc)

Flags Affected: None

Example of Usage:
GetOutAdrs
mov word ptr SaveOutAdrs, DI
mov word ptr SaveOutAdrs+2, ES

Description: GetOutAdrs gets the address of the current output routine, perhaps
so you can save it or see if it is currently pointing at some
particular piece of code. If you want to temporarily redirect
the output and then restore the original output routine, consider
using PushOutAdrs/PopOutAdrs described later.

Include:stdlib.a or stdout.a




Routine: SetOutAdrs
--------------------

Category: Character Output Routine

Registers on Entry: ES:DI - address of new output routine

Registers on return: None

Flags affected: None

Example of Usage:

mov es, seg NewOutputRoutine
mov di, offset NewOutputRoutine
SetOutAdrs
les di, RoutinePtr
SetOutAdrs

Description: This routine redirects the stdlib standard output so that it
calls the routine who's address you pass in es:di. This routine
expects the character to be in AL and must preserve all registers.
It handles the printable ASCII characters and the four control
characters return, line feed, back space, and tab. (The routine
may be modified in the case that you wish to handle these codes
in a different fashion.)


Include: stdlib.a or stdout.a


Routine: PushOutAdrs
---------------------

Category: Character Output Routine

Registers on Entry: ES:DI- Address of new output routine

Registers on Return: None

Flags Affected: Carry = 0 if operation is successful
Carry = 1 if there were already 16 items on the stack

Example of Usage:
mov ES, seg NewOutputRoutine
mov DI, offset NewOutputRoutine
PushOutAdrs
.
.
.
les DI, RoutinePtr
PushOutAdrs


Description: This routine "pushes" the current output address onto an internal
stack and then uses the value in es:di as the current output
routine address. The PushOutAdrs and PopOutAdrs routines let you
easily save and redirect the standard output and then restore the
original output routine address later on. If you attempt to push
more than 16 items on the stack, PushOutAdrs will ignore your
request and return with the carry flag set. If PushOutAdrs is
successful, it will return with the carry flag clear.


Include: stdlib.a or stdout.a



Routine: PopOutAdrs
--------------------

Category: Character Output Routine

Registers on Entry: None

Registers on Return: ES:DI- Points at the previous stdout routine before
the pop

Flags Affected: None

Example of Usage:
mov ES, seg NewOutputRoutine
mov DI, offset NewOutputRoutine
PushOutAdrs
.
.
.
PopOutAdrs


Description: PopOutAdrs undoes the effects of PushOutAdrs. It pops an item off
the internal stack and stores it into the output routine pointer.
The previous value in the output pointer is returned in es:di.
Defaults to PutcStdOut if you attempt to pop too many items off
the stack.

Include:stdlib.a or stdout.a




Routine: Puts
--------------

Category: Character Output Routine

Register on entry: ES:DI register - contains the address of the string

Register on return: None

Flags affected: None

Example of Usage:
les di, StrToPrt
puts
putcr


Description: Puts prints a zero-terminated string whose address appears
in es:di. Each character appearing in the string is printed
verbatim. There are no special escape characters. Unlike
the "C" routine by the same name, puts does not print a
newline after printing the string. Use putcr if you want
to print the newline after printing a string with puts.


Include: stdlib.a or stdout.a



Routine: Puth
--------------

Category: Character Output Routine

Register on entry: AL

Register on return: AL

Flags affected: None

Example of Usage:
mov al, 1fh
puth


Description: The Puth routine Prints the value in the AL register as two
hexadecimal digits. If the value in AL is between 0 and 0Fh,
puth will print a leading zero. This routine calls the stdlib
standard output routine (putc) to print all characters.


Include: stdlib.a or stdout.a



Routine: Putw
--------------

Category: Character Output Routine

Registers on Entry: AX- Value to print

Registers on Return: None

Flags Affected: None

Example of Usage:
mov AX, 0f1fh
putw


Description: The Putw routine prints the value in the AX register as four
hexadecimal digits (including leading zeros if necessary).
This routine calls the stdlib standard output routine (putc)
to print all characters.

Include: stdlib.a or stdout.a



Routine: Puti
--------------

Category: Character Output Routine

Registers on Entry: AX- Value to print

Registers on Return: None

Flags Affected: None

Example of Usage:
mov AX, -1234
puti


Description: Puti prints the value in the AX register as a decimal integer.
This routine uses the exact number of screen positions required
to print the number (including a position for the minus sign, if
the number is negative). This routine calls the stdlib standard
output routine (putc) to print all characters.


Include: stdlib.a or stdout.a



Routine: Putu
--------------

Category: Character Output Routine

Register on entry: AX- Unsigned value to print.

Register on return: None

Flags affected: None

Example of Usage:
mov ax, 1234
putu


Description: Putu prints the value in the AX register as an unsigned integer.
This routine uses the exact number of screen positions required
to print the number. This routine calls the stdlib standard
output routine (putc) to print all characters.


Include: stdlib.a or stdout.a




Routine: Putl
--------------

Category: Character Output Routine

Register on entry: DX:AX- Value to print

Register on return: None

Flags affected: None

Example of Usage:
mov dx, 0ffffh
mov ax, -1234
putl


Description: Putl prints the value in the DX:AX registers as an integer.
This routine uses the exact number of screen positions
required to print the number (including a position for the
minus sign, if the number is negative). This routine calls
the stdlib standard output routine (putc) to print all
characters.


Include: stdlib.a or stdout.a



Routine: Putul
---------------

Category: Character Output Routine

Register on entry: DX:AX register

Register on return: None

Flags affected: None

Example of Usage:
mov dx, 12h
mov ax, 1234
putul


Description: Putul prints the value in the DX:AX registers as an unsigned
integer. This routine uses the exact number of screen
positions required to print the number. This routine calls
the stdlib standard output routine (putc) to print all
characters.


Include: stdlib.a or stdout.a


Routine: PutISize
------------------

Category: Character Output Routine

Registers on Entry: AX - Integer value to print
CX - Minimum number of print positions to use

Registers on return: None

Flags affected:

Example of Usage:
mov cx, 5
mov ax, I
PutISize
.
.
.
mov cx, 12
mov ax, J
PutISize


Description: PutISize prints the signed integer value in AX to the
stdlib standard output device using a minimum of n print
positions. CX contains n, the minimum field width for the
output value. The number (including any necessary minus sign)
is printed right justified in the output field.
If the number in AX requires more print positions than
specified by CX, PutISize uses however many print positions
are necessary to actually print the number. If you specify
zero in CX, PutISize uses the minimum number of print positions
required. Of course, PutI will also use the minimum number
of print positions without disturbing the value in the CX
register.

Note that, under no circumstances, will the number in AX
ever require more than 6 print positions (-32,767 requires
the most print positions).


Include: stdlib.a or stdout.a



Routine: PutUSize
------------------

Category: Character Output Routine

Registers on entry: AX- Value to print
CX- Minimum field width

Registers on return: None

Flags affected: None

Example of usage:
mov cx, 8
mov ax, U
PutUSize


Description: PutUSize prints the value in AX as an unsigned decimal integer.
The minimum field width specified by the value in CX.
Like PutISize above except this one prints unsigned values.
Note that the maximum number of print positions required by any
number (e.g., 65,535) is five.


Include: stdlib.a or stdout.a



Routine: PutLSize
------------------

Category: Character Output Routine

Register on entry: DX:AX-32 bit value to print
CX- Minimum field width

Register on return: None

Flags affected: None

Example of Usage:
mov cx, 16
mov dx, word ptr L+2
mov ax, word ptr L
PutLSize


Description: PutLSize is similar to PutISize, except this prints the long
integer value in DX:AX. Note that there may be as many as
11 print positions (e.g., -1,000,000,000).

Include: stdlib.a or stdout.a




Routine: PutULSize
-------------------


Category: Character Output Routine


Register on entry: AX : DX and CX


Register on return: None


Flags affected: None


Example of usage: mov cx, 8
mov dx, word ptr UL+2
mov ax, word ptr UL
PutULSize


Description: Prints the value in DX:AX as a long unsigned decimal integer.
Prints the number in a minimum field width specified by the
value in CX. Just like PutLSize above except this one prints
unsigned numbers rather than signed long integers. The largest
field width for such a value is 10 print positions.


Include: stdlib.a or stdout.a


Routine: Print
----------------

Category: Character Output Routine

Register on entry: CS:RET - Return address points at the string to print.

Register on return: None

Flags affected: None

Examples of Usage: print
db "Print this string to the display device"
db 13,10
db "This appears on a new line"
db 13,10
db 0


Description: Print lets you print string literals in a convenient
fashion. The string to print immediately follows the call
to the print routine. The string must contain a
zero terminating byte and may not contain any intervening
zero bytes. Since the print routine returns to the address
immediately following the zero terminating byte, forgetting
this byte or attempting to print a zero byte in the middle
of a literal string will cause print to return to an
unexpected instruction. This usually hangs up the machine.
Be very careful when using this routine!


Include: stdlib.a or stdout.a


Routine: Printf
----------------------

Category: Character Output Routine

Register on entry: CS:RET - Return address points at the format string

Register on return: None

Flags affected: None

Example of Usage:
printf
db "Indirect access to i: %^d",13,10,0
dd IPtr;
printf
db "A string allocated on the heap: %-\.32^s"
db 13,10,0
dd SPtr



Descriptions: Printf, like its "C" namesake, provides formatted output
capabilities for the stdlib package. A typical call to printf
always takes the following form:

printf
db "format string",0
dd operand1, operand2, ..., operandn

The format string is comparable to the one provided in the
"C" programming language. For most characters, printf simply
prints the characters in the format string up to the
terminating zero byte. The two exceptions are characters
prefixed by a backslash ("\") and characters prefixed by a
percent sign ("%"). Like C's printf, stdlib's printf uses
the backslash as an escape character and the percent sign as
a lead-in to a format string.

Printf uses the escape character ("\") to print special
characters in a fashion similar to, but not identical to C's
printf. Stdlib's printf routine supports the following
special characters:

* r Print a carriage return (but no line feed)
* n Print a new line character (carriage return/line feed).
* b Print a backspace character.
* t Print a tab character.
* l Print a line feed character (but no carriage return).
* f Print a form feed character.
* \ Print the backslash character.
* % Print the percent sign character.
* 0xhh Print ASCII code hh, represented by two hex digits.

C users should note a couple of differences between stdlib's
escape sequences and C's. First, use "\%" to print a percent
sign within a format string, not "%%". C doesn't allow the
use of "\%" because the C compiler processes "\%" at compile
time (leaving a single "%" in the object code) whereas printf
processes the format string at run-time. It would see a single
"%" and treat it as a format lead-in character. Stdlib's
printf, on the other hand, processes both the "\" and "%" and
run-time, therefore it can distinguish "\%".

Strings of the form "\0xhh" must contain exactly two hex
digits. The current printf routine isn't robust enough to
handle sequences of the form "\0xh" which contain only a
single hex digit. Keep this in mind if you find printf
chopping off characters after you print a value.

There is absolutely no reason to use any escape character
sequences except "\0x00". Printf grabs all characters
following the call to printf up to the terminating zero byte
(which is why you'd need to use "\0x00" if you want to print
the null character, printf will not print such values).
Stdlib's printf routine doesn't care how those characters got
there. In particular, you are not limited to using a single
string after the printf call. The following is perfectly
legal:


printf
db "This is a string",13,10
db "This is on a new line",13,10
db "Print a backspace at the end of this line:"
db 8,13,10,0


Your code will run a tiny amount faster if you avoid the use
of the escape character sequences. More importantly, the
escape character sequences take at least two bytes. You can
encode most of them as a single byte by simply embedding the
ASCII code for that byte directly into the code stream.
Don't forget, you cannot embed a zero byte into the code
stream. A zero byte terminates the format string. Instead,
use the "\0x00" escape sequence.

Format sequences always between with "%". For each format
sequence you must provide a far pointer to the associated
data immediately following the format string, e.g.,

printf
db "%i %i",0
dd i,j

Format sequences take the general form "%s\cn^f" where:

* "%" is always the "%" character. Use "\%" if you
actually want to print a percent sign.
* s is either nothing or a minus sign ("-").
* "\c" is also optional, it may or may not appear in
the format item. "c" represents any printable
character.
* "n" represents a string of 1 or more decimal digits.
* "^" is just the caret (up-arrow) character.
* "f" represents one of the format characters: i, d, x,
h, u, c, s, ld, li, lx, or lu.

The "s", "\c", "n", and "^" items are optional, the "%" and
"f" items must be present. Furthermore, the order of these
items in the format item is very important. The "\c" entry,
for example, cannot precede the "s" entry. Likewise, the "^"
character, if present, must follow everything except the "f"
character(s).

The format characters i, d, x, h, u, c, s, ld, li, lx, and
lu control the output format for the data. The i and d
format characters perform identical functions, they tell
printf to print the following value as a 16-bit signed
decimal integer. The x and h format characters instruct
printf to print the specified value as a 16-bit or 8-bit
hexadecimal value (respectively). If you specify u, printf
prints the value as a 16-bit unsigned decimal integer.
Using c tells printf to print the value as a single character.
S tells printf that you're supplying the address of a
zero-terminated character string, printf prints that string.
The ld, li, lx, and lu entries are long (32-bit) versions of
d/i, x, and u. The corresponding address points at a 32-bit
value which printf will format and print to the standard output.
The following example demonstrates these format items:

printf
db "I= %i, U= %u, HexC= %h, HexI= %x, C= %c, "
db "S= %s",13,10
db "L= %ld",13,10,0
dd i,u,c,i,c,s,l

The number of far addresses (specified by operands to the "dd"
pseudo-opcode) must match the number of "%" format items in
the format string. Printf counts the number of "%" format
items in the format string and skips over this many far
addresses following the format string. If the number of
items do not match, the return address for printf will be
incorrect and the program will probably hang or otherwise
malfunction. Likewise (as for the print routine), the format
string must end with a zero byte. The addresses of the items
following the format string must point directly at the memory
locations where the specified data lies.

When used in the format above, printf always prints the
values using the minimum number of print positions for each
operand. If you want to specify a minimum field width, you
can do so using the "n" format option. A format item of the
format "%10d" prints a decimal integer using at least ten
print positions. Likewise, "%16s" prints a string using at
least 16 print positions. If the value to print requires
more than the specified number of print positions, printf
will use however many are necessary. If the value to print
requires fewer, printf will always print the specified number,
padding the value with blanks. Printf will print the value
right justified in the print field (regardless of the data's
type). If you want to print the value left justified in the
output file, use the "-" format character as a prefix to the
field width, e.g.,

printf
db "%-17s",0
dd string

In this example, printf prints the string using a 17 character
long field with the string left justified in the output field.
By default, printf blank fills the output field if the value
to print requires fewer print positions than specified by the
format item. The "\c" format item allows you to change the
padding character. For example, to print a value, right
justified, using "*" as the padding character you would use
the format item "%\*10d". To print it left justified you
would use the format item "%-\*10d". Note that the "-" must
precede the "\*". This is a limitation of the current
version of the software. The operands must appear in this
order. Normally, the address(es) following the printf
format string must be far pointers to the actual data to print.
On occasion, especially when allocating storage on the heap
(using malloc), you may not know (at assembly time) the
address of the object you want to print. You may have only
a pointer to the data you want to print. The "^" format
option tells printf that the far pointer following the format
string is the address of a pointer to the data rather than
the address of the data itself. This option lets you access
the data indirectly.

Note: unlike C, stdlib's printf routine does not support
floating point output. Putting floating point into printf
would increase the size of this routine a tremendous amount.
Since most people don't need the floating point output
facilities, it doesn't appear here. Check out PRINTFF.

Include: stdlib.a or stdout.a



Routine: PRINTFF
-----------------


Category: Character Output Routine

Registers on Entry: CS:RET- Points at format string and other parameters.

Registers on Return: If your program prints floating point values, this
routine modifies the floating point accumulator and
floating point operand "pseudo-registers" in the
floating point package.

Flags Affected: None

Examples of Usage:
printff
db"I = %d, R = %7.2f F = 12.5e G = 9.2gf\n",0
ddi, r, f, g

Description:
This code works just like printf except it also allows the
output of floating point values. The output formats are
the following:

Single Precision:

mm.nnF-Prints a field width of mm chars with nn digits
appearing after the decimal point.

nnE-Prints a floating point value using scientific
notation in a field width of nn chars.

Double Precision:

mm.nnGF-As above, for double precision values.
nnGE-As above, for double precision values.

Extended Precision-

mm.nnLF-As above, for extended precision values.
nnLE-As above, for extended precision values.


Since PRINTFF supports everything PRINTF does, you should not
use both routines in the same program (just use PRINTF). The
PRINTF & PRINTFF macros check for this and will print a warning
message if you've included both routines. Using both will not
cause your program to fail, but it will make your program
unnecessarily larger. You should not use PRINTFF unless you
really need to print floating point values. When you use
PRINTFF, it forces the linker to load in the entire floating
point package, making your program considerably larger.

Include: stdlib.a or fp.a



Conversion Routines
-------------------


The stdlib conversion routines follow a uniform format of storing the data
to be converted and returned. Most routines accept input and return data
of either an ASCII string of characters, stored in the ES:DI register, or
integers, stored in the DX:AX register. If a value is just a 16 or 8-bit
value then it will be stored in AX or AL.

Since there is a possibility of an error in the input values to be converted,
such as it does not contain a proper value to convert, we use the
carry flag to show error status. If the error flag is set then an error has
occured and things are okay if the carry flag is clear.





Routine: ATOL (2)
------------------


Category: Conversion Routine

Registers on Entry: ES:DI- Points at string to convert

Registers on Return: DX:AX- Long integer converted from string
ES:DI- Points at first non-digit (ATOL2 only)

Flags Affected: Carry flag- Error status

Examples of Usage:
gets ;Get a string from user
ATOL ;Convert to a value in DX:AX


Description: ATOL converts the string of digits that ES:DI points at to a
long (signed) integer value and returns this value in DX:AX.
Note that the routine stops on the first non-digit.
If the string does not begin with a digit, this routine returns
zero. The only exception to the "string of digits" only rule is
that the number can have a preceding minus sign to denote a
negative number. Note that this routine does not allow leading
spaces. ATOL2 works in a similar fashion except it doesn't
preserve the DI register. That is, ATOL2 leaves DI pointing at
the first character beyond the string of digits. ATOL/ATOL2 both
return the carry flag clear if it translated the string of
digits without error. It returns the carry flag set if overflow
occurred.


Include: stdlib.a or conv.a



Routine: AtoUL (2)
-------------------

Category: Conversion Routine

Register on entry: ES:DI- address of the string to be converted

Register on return: DX:AX- 32-bit unsigned integer
ES:DI- Points at first character beyond digits (ATOUL2
only)

Flags affected: Carry flag- Set if error, clear if okay.

Examples of Usage:
les InputString
AtoUL


Description: AtoUL converts the string pointed by ES:DI to a 32-bit unsigned
integer. It places the 32-bit unsigned integer into the memory
address pointed by DX:AX. If there is an error in conversion,
the carry flag will set to one. If there is not an error, the
carry flag will be set to zero.

ATOUL2 does not preserve DI. It returns with DI pointing at
the first non-digit character in the string.

Include: stdlib.a or conv.a



Routine: ATOU (2)
--------------------

Category: Conversion Routine

Register on entry: ES:DI points at string to convert

Register on return: AX- unsigned 16-bit integer
ES:DI- points at first non-digit (ATOU2 only)

Flags affected: carry flag - error status

Example of Usage:

Description: ATOU converts an ASCII string of digits, pointed to by ES:DI,
to unsigned integer format. It places the unsigned 16-bit
integer, converted from the string, into the AX register.
ATOI works the same, except it handle unsigned 16-bit integers
in the range 0..65535.

ATOU2 leaves DI pointing at the first non-digit in the string.

Include: stdlib.a or conv.a



Routine: ATOH (2)
-----------------

Category: Conversion Routine

Registers on Entry: ES:DI- Points to string to convert

Registers on Return: AX- Unsigned 16-bit integer converted from hex string
DI (ATOH2)- First character beyond string of hex digits

Flags Affected: Carry = Error status

Example of Usage:
les DI, Str2Convrt
atoh ;Convert to value in AX.
putw ;Print word in AX.


Description: ATOH converts a string of hexadecimal digits, pointed to by
ES:DI, into unsigned 16-bit numeric form. It returns the value in
the AX register. If there is an error in conversion, the carry
flag will set to one. If there is not an error, the carry flag
will be clear. ATOH2 works the same except it leaves DI
pointing at the first character beyond the string of hex digits.

Include: stdlib.a or conv.a


Routine: ATOLH (2)
------------------

Category: Conversion Routine

Registers on Entry: ES:DI- Points to string to convert

Registers on Return: DX:AX- Unsigned 32-bit integer converted from hex string
DI (ATOLH2)- First character beyond string of hex digits

Flags Affected: Carry = Error status

Example of Usage:
les DI, Str2Convrt
atolh ;Convert to value in DX:AX

Description: ATOLH converts a string of hexadecimal digits, pointed to by
ES:DI, into unsigned 32-bit numeric form. It returns the value in
the DX:AX register. If there is an error in conversion, the carry
flag will set to one. If there is not an error, the carry flag
will be clear. ATOLH2 works the same except it leaves the DI
register pointing at the first non-hex digit.


Include: stdlib.a or conv.a



Routine: ATOI (2)
-------------------

Category: Conversion Routine

Register on entry: ES:DI- Points at string to convert.

Register on return: AX- Integer converted from string.
DI (ATOI2)- First character beyond string of digits.

Flags affected: Error status

Examples of Usage:
les DI, Str2Convrt
atoi ;Convert to value in AX


Description: Works just like ATOL except it translates the string to a
signed 16-bit integer rather than a 32-bit long integer.


Include: stdlib.a or conv.a


Routine ITOA (2,M)
------------------

Category: Conversion Routine

Registers on Entry: AX- Signed 16-bit value to convert to a string
ES:DI- Pointer to buffer to hold result (ITOA/ITOA2
only).

Registers on Return: ES:DI- Pointer to string containing converted
characters (ITOA/ITOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (ITOA2 only).

Flags Affected: Carry flag is set on memory allocation error (ITOAM only)

Examples of Usage:
mov ax, -1234
ITOAM ;Convert to string.
puts ;Print it.
free ;Deallocate string.

mov di, seg buffer
mov es, di
lea di, buffer
mov ax, -1234
ITOA ;Leaves string in BUFFER.

mov di, seg buffer
mov es, di
lea di, buffer
mov ax, -1234
ITOA2 ;Leaves string in BUFFER and
;ES:DI pointing at end of string.


Description:These routines convert an integer value to a string of
characters which represent that integer. AX contains the
signed integer you wish to convert.

ITOAM automatically allocates storage on the heap for the
resulting string, you do not have to pre-allocate this
storage. ITOAM returns a pointer to the (zero-terminated)
string in the ES:DI registers. It ignores the values in
ES:DI on input.

ITOA requires that the caller allocate the storage for the
string (maximum you will need is seven bytes) and pass a
pointer to this buffer in ES:DI. ITOA returns with ES:DI
pointing at the beginning of the converted string.

ITOA2 also requires that you pass in the address of a buffer
in the ES:DI register pair. However, it returns with ES:DI
pointing at the zero-terminating byte of the string. This
lets you easily build up longer strings via multiple calls
to routines like ITOA2.

Include: stdlib.a or conv.a



Routine: UTOA (2,M)
---------------------

Category: Conversion Routine

Registers on entry: AX - unsigned 16-bit integer to convert to a string
ES:DI- Pointer to buffer to hold result (UTOA/UTOA2
only).

Registers on Return: ES:DI- Pointer to string containing converted
characters (UTOA/UTOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (UTOA2 only).

Flags affected: Carry set denotes malloc error (UTOAM only)

Example of Usage:
mov ax, 65000
utoa
puts
free

mov di, seg buffer
mov es, di
lea di, buffer
mov ax, -1234
ITOA ;Leaves string in BUFFER.


mov di, seg buffer
mov es, di
lea di, buffer
mov ax, -1234
ITOA2 ;Leaves string in BUFFER and
;ES:DI pointing at end of string.


Description: UTOAx converts a 16-bit unsigned integer value in AX to a
string of characters which represents that value. UTOA,
UTOA2, and UTOAM behave in a manner analogous to ITOAx. See
the description of those routines for more details.


Include: stdlib.a or conv.a



Routine: HTOA (2,M)
---------------------

Category: Conversion Routine

Registers on entry: AL - 8-bit integer to convert to a string
ES:DI- Pointer to buffer to hold result (HTOA/HTOA2
only).

Registers on Return: ES:DI- Pointer to string containing converted
characters (HTOA/HTOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (HTOA2 only).

Flags affected: Carry set denotes memory allocation error (HTOAM only)


Description: The HTOAx routines convert an 8-bit value in AL to the two-
character hexadecimal representation of that byte. Other
that that, they behave just like ITOAx/UTOAx. Note that
the resulting buffer must have at least three bytes for
HTOA/HTOA2.


Include: stdlib.a or conv.a


Routine: WTOA (2,M)
--------------------

Category: Conversion Routine

Registers on Entry: AX- 16-bit value to convert to a string
ES:DI- Pointer to buffer to hold result (WTOA/WTOA2
only).

Registers on Return: ES:DI- Pointer to string containing converted
characters (WTOA/WTOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (WTOA2 only).

Flags Affected: Carry set denotes memory allocation error (WTOAM only)

Example of Usage:
Like WTOA above


Description: WTOAx converts the 16-bit value in AX to a string of four
hexadecimal digits. It behaves exactly like HTOAx except
it outputs four characters (and requires a five byte buffer).


Include: stdlib.a or conv.a



Routine: LTOA (2,M)
--------------------

Category: Conversion Routine

Registers on entry: DX:AX (contains a signed 32 bit integer)
ES:DI- Pointer to buffer to hold result (LTOA/LTOA2
only).

Registers on Return: ES:DI- Pointer to string containing converted
characters (LTOA/LTOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (LTOA2 only).

Flags affected: Carry set if memory allocation error (LTOAM only)


Example of Usage:
movdi, seg buffer;Get address of storage
moves, di; buffer.
leadi, buffer
movax, word ptr value
movdx, word ptr value+2
ltoa

Description: LtoA converts the 32-bit signed integer in DX:AX to a string
of characters. LTOA stores the string at the address specified
in ES:DI (there must be at least twelve bytes available at
this address) and returns with ES:DI pointing at this buffer.
LTOA2 works the same way, except it returns with ES:DI
pointing at the zero terminating byte. LTOAM allocates
storage for the string on the heap and returns a pointer
to the string in ES:DI.

Include: stdlib.a or conv.a



Routine: ULTOA (2,M)
---------------------

Category: Conversion Routine

Registers on Entry: DX:AX- Unsigned 32-bit value to convert to a string
ES:DI- Pointer to buffer to hold result (LTOA/LTOA2
only).
Registers on Return: ES:DI- Pointer to string containing converted
characters (LTOA/LTOAM only).
ES:DI- Pointer to zero-terminating byte of converted
string (LTOA2 only).

Flags Affected: Carry is set if malloc error (ULTOAM only)

Example of Usage:
Like LTOA


Description: Like LTOA except this routine handles unsigned integer values.

Include:stdlib.a or conv.a



Routine: SPrintf (2,M)
-----------------------

Category: Conversion Routine
In-Memory Formatting Routine

Registers on entry: CS:RET - Pointer to format string and operands of the
sprintf routine
ES:DI- Address of buffer to hold output string
(sprintf/sprintf2 only)

Register on return: ES:DI register - pointer to a string containing
output data (sprintf/sprintfm only).
Pointer to zero-terminating byte at the
end of the converted string (sprintf2
only).

Flags affected: Carry is set if memory allocation error (sprintfm only).

Example of Usage:
sprintfm
db "I=%i, U=%u, S=%s",13,10,0
db i,u,s
puts
free


Description: SPrintf is an in-memory formatting routine. It is similar to
C's sprintf routine.

The programmer selects the maximum length of the output string.
SPrintf works in a manner quite similar to printf, except sprintf
writes its output to a string variable rather than to the stdlib
standard output.

SPrintfm, by default, allocates 2048 characters for the string
and then deallocates any unnecessary storage. An external
variable, sp_MaxBuf, holds the number of bytes to allocate upon
entry into sprintfm. If you wish to allocate more or less than
2048 bytes when calling sprintf, simply change the value of this
public variable (type is word). Sprintfm calls malloc to
allocate the storage dynamically. You should call free to
return this buffer to the heap when you are through with it.

Sprintf and Sprintf2 expect you to pass the address of a buffer
to them. You are responsible for supplying a sufficiently
sized buffer to hold the result.

Include: stdlib.a or conv.a



Routine: SScanf
----------------

Category: Conversion Routine
Formatted In-Memory Conversion Routine

Registers on Entry: ES:DI - points at string containing values to convert

Registers on return: None

Flags affected: None

Example of Usage:

; this code reads the values for i, j, and s from the characters
; starting at memory location Buffer.

les di, Buffer
SScanf
db "%i %i %s",0
dd i, j, s


Description: SScanf provides formatted input in a fashion analogous to scanf.
The difference is that scanf reads in a line of text from the
stdlib standard input whereas you pass the address of a sequence
of characters to SScanf in es:di.


Include: stdlib.a or conv.a




Routine: ToLower
-----------------

Category: Conversion Routine

Register on entry: AL- Character to (possibly) convert
to lower case.

Register on return: AL- Converted character.

Flags affected: None

Example of usage:
mov al, char
ToLower



Description: ToLower checks the character in the AL register, if it is upper
case it converts it to lower case. If it is anything else,
ToLower leaves the value in AL unchanged. For high performance
this routine is implemented as a macro rather than as a
procedure call. This routine is so short you would spend more
time actually calling the routine than executing the code inside.
However, the code is definitely longer than a (far) procedure
call, so if space is critical and you're invoking this code
several times, you may want to convert it to a procedure call to
save a little space.


Include: stdlib.a or conv.a



Routine: ToUpper
------------------

Category: Conversion Routine

Registers on Entry: AL- Character to (possibly) convert to upper case

Registers on Return: AL- Converted character

Flags Affected: None

Example of Usage:
mov al, char
ToUpper


Description: ToUpper checks the character in the AL register, if it is lower
case it converts it to upper case. If it is anything else,
ToUpper leaves the value in AL unchanged. For high performance
this routine is implemented as a macro rather than as a
procedure call (see ToLower, above).


Include: stdlib.a or conv.a





Utility Routines
----------------

The following routines are all Utility Routines. The first routines listed
below compute the number of print positions required by a 16-bit and 32-bit
signed and unsigned integer value. UlSize is like the LSize except it treats
the value in DX:AX as an unsigned long integer. The next set of routines in
this section check the character in the AL register to see whether it is a
hexidecimal digit, if it alphabetic, if it is a lower case alphabetic, if it
is a upper case alphabetic, and if it is numeric. Then there are some
miscellaneous routines (macros) which process command line parameters, invoke
DOS and exit the program.



Routine: ISize
---------------

Category: Utility Routine

Register on entry: AX- 16-bit value to compute the
output size for.

Register on return: AX- Number of print positions
required by this number (including
the minus sign, if necessary).

Flags affected: None

Example of usage:
mov ax, I
ISize
puti ;Prints positions
;req'd by I.


Description: This routine computes the number of print positions
required by a 16-bit signed integer value. ISize computes
the minimum number of character positions it takes to print
the signed decimal value in the AX register. If the number
is negative, it will include space for the minus sign in
the count.


Include: stdlib.a or util.a




Routine: USize
---------------

Category: Utility Routine

Register on entry: AX- 16 bit value to compute the
output size for

Register on return: AX- number of print positions
required by this number (including
the minus sign, if necessary)

Flags affected: None

Example of usage:
mov ax, I
USize
puti ;prints position
;required by I


Description: This routine computes the number of print positions
required by a 16-bit signed integer value. It also
computes the number of print positions required by a
16-bit unsigned value. USize computes the minimum number
of character positions it will take to print an unsigned
decimal value in the AX register. If the number is
negative, it will include space for the minus sign in the
count.


Include: stdlib.a or util.a


Routine: LSize
---------------

Category: Utility Routine

Register on entry: DX:AX - 32-bit value to compute the
output size for.

Register on return: AX - Number of print positions
required by this number (including
the minus sign, if necessary).

Flags affected: None

Example of Usage:
mov ax, word ptr L
mov dx, word ptr L+2
LSize
puti ;Prints positions
;req'd by L.


Description: This routine computes the number of print positions
required by a 32-bit signed integer value. LSize computes
the minimum number of character positions it will take to
print the signed decimal value in the DX:AX registers. If
the number is negative, it will include space for the minus
sign in the count.


Include: stdlib.a or util.a



Routine: ULSize
----------------

Category: Utility Routine

Registers on Entry: DX:AX - 32-bit value to compute the output size for.

Registers on return: AX - number of print positions required by this number

Flags affected: None

Example of Usage:
mov ax, word ptr L
mov dx, word ptr L+2
ULSize
puti ; Prints positions req'd by L


Description: ULSize computes the minimum number of character
positions it will take to print an unsigned decimal
value in the DX:AX registers.


Include: stdlib.a or util.a



Routine: IsAlNum
-----------------

Category: Utility routine

Register on entry: AL - character to check.

Register on return: None

Flags affected: Zero flag - set if character is alphanumeric,
clear if not.


Example of usage : mov al, char
IsAlNum
je IsAlNumChar


Description : This routine checks the character in the AL register to
see if it is in the range A-Z, a-z, or 0-9. Upon return,
you can use the JE instruction to check to see if the
character was in this range (or, conversely, you can use
JNE to see if it is not in range).


Include: stdlib.a or util.a


Routine: IsXDigit
------------------

Category: Utility Routine

Register on Entry: AL- character to check

Registers on Return: None

Flags Affected: Zero flag- Set if character is a hex digit, clear if not


Example of Usage: mov al, char
IsXDigit
je IsXDigitChar


Description: This routine checks the character in the AL register to
see if it is in the range A-F, a-f, or 0-9. Upon
return, you can use the JE instruction to check to see
if the character was in this range (or, conversely,
you can use jne to see if it is not in the range).


Include: stdlib.a or util.a


Routine: IsDigit
------------------

Category: Utility Routine

Register on entry: AL- Character to check

Register on return: None

Flags affected: Zero flag- set if character is numeric, clear if not.

Example of Usage: mov al, char
IsDigit
je IsDecChar


Description: This routine checks the character in the AL register to
see if it is in the range 0-9. Upon return, you can use
the JE instruction to check to see if the character was
in the range (or, conversely, you can use JNE to see if it
is not in the range).


Include: stdlib.a or util.a


Routine: IsAlpha
------------------

Category: Utility Routine

Register on entry: AL- Character to check

Register on return: None

Flags affected: Zero flag- set if character is alphabetic, clear if not.

Example of Usage: mov al, char
IsAlpha
je IsAlChar


Description: This routine checks the character in the AL register to
see if it is in the range A-Z or a-z. Upon return, you
can use the JE instruction to check to see if the character
was in the range (or, conversely, you can use JNE to see
if it is not in the range).

Include: stdlib.a or util.a




Routine: IsLower
----------------

Category: Utility Routine

Registers on Entry: AL- character to test

Registers on Return: None


Flags Affected: Zero = 1 if character is a lower case alphabetic character
Zero = 0 if character is not a lower case alphabetic
character

Example of Usage: mov AL, char ; put char in AL
IsLower ; is char lower a-z?
je IsLowerChar ; if yes, jump to IsLowerChar


Description: This routine checks the character in the AL register to
see if it is in the range a-z. Upon return, you can use
the JE instruction to check and see if the character was
in this range (or you can use JNE to check and see if
the character was not in this range). This procedure is
implemented as a macro for high performance.


Include: stdlib.a or util.a


Routine: IsUpper
-----------------

Category: Utility Routine

Registers on Entry: AL- character to check

Registers on Return: None

Flags Affected: Zero flag - set if character is uppercase alpha, clear
if not.


Example of Usage: mov al, char
IsUpper
je IsUpperChar


Description: This routine checks the character in the AL register to
see if it is in the ranger A-Z. Upon return, you can use
the JE instruction to check to see if it not in the
range). It uses macro implementation for high performance.


Include: stdlib.a or util.a


Routine: Argc
--------------

Category: Utility Routine

Registers on Entry: None

Registers on Return: CX-Number of command line parameters

Flags Affected: None


Example of Usage:
print
db"There were ",0
argc
movax, cx
puti
print
db" command line parameters here",cr,lf,0

Description: This routine returns the number of command line para-
meters on the DOS command line. Note that strings enclosed
in quotation marks or apostrophes are counted as a single
command line parameter.


Include: stdlib.a or misc.a


Routine: Argv
--------------

Category: Utility Routine

Registers on Entry: AX-Which parameter to grab (1..n).
PSP-Global variable containing the DOS program
segment prefix value.

Registers on Return: ES:DI-Pointer to string on heap containing the
specified parameter (empty string if the
parameter does not exist).

Flags Affected: carry-Set if malloc error.


Example of Usage:
movax, 2
argv
print
db"The second command line parameter is ",0
puts
free

Description:
This routine returns a string containing the specified command line argument.
You must pass the position number of the argument in AX; this routine returns
the specified string on the heap with ES:DI pointing at the string. Note that
the command line parameters are numbered starting from one. If you specify an
out of range value, this routine returns a pointer to a zero byte (the empty
string).


Include: stdlib.a or misc.a


Routine: GetEnv
----------------

Category: Utility Routine

Registers on Entry: ES:DI-Points at a string containing the name of
the environment variable you want to find.
PSP-Global variable containing the DOS program
segment prefix value.

Registers on Return: ES:DI-Pointer to string in the environment space
containing the characters immediately after
the name of the environment variable in the
environment string space.

Flags Affected: carry-Set if malloc error.


Example of Usage:
lesdi, EnvVarStrPtr
getenv
print
db"The value of the environment variable is ",0
puts
free

Description:

This routine returns a pointer to the first characters following an

environment variable in the program's environment variable space. It points
at the very first character following the name, so it typically points at
an equal sign (e.g., the PATH environment variable is typically of the form
"PATH=xxxxxxxx" and the "=" is the first char past the name). If this routine
does not find the specified environment variable, it returns a pointer to
a single zero byte. Since the pointer is in the environment space, you should
not store anything at this address. Instead, first copy the string with STRDUP
if you need to modify it.

Include: stdlib.a or misc.a


Routine: DOS
-------------

Category: Utility Routine

Registers on Entry: AH-DOS opcode

Registers on Return: Depends on particular DOS call

Flags Affected: Depends on DOS call.


Example of Usage:
movah, 9
DOS
.
.
.
DOS7
Description:

This macro invokes DOS via the INT 21h interrupt. If there is no parameter
to the macro, it simply issues the INT 21h instruction. If a parameter is
present, it emits "mov ah, operand" followed by the INT 21h instruction.

Include: stdlib.a or consts.a


Routine: ExitPgm
-----------------

Category: Utility Routine

Registers on Entry: None

Registers on Return: Doesn't return

Flags Affected: N/A


Example of Usage:
ExitPgm
Description:

This macro exits the program and returns to DOS.

Include: stdlib.a or consts.a



String Handling Routines
------------------------

Manipulating text is a major part of many computer applications. Typically,
strings are inputed and interpreted. This interpretation may involve some
chores such as extracting certain part of the text, copying it, or comparing
with other strings.

The string manipulation routines in C provides various functions. Therefore,
the stdlib has some C-like string handling functions (e.g. strcpy, strcmp).
In C a string is an array of characters; similarly, the string are terminated
by a "0" as a null character. In general, the input strings of these routines
are pointed by ES:DI. In some routines, the carry flag will be set to indicate
an error.

The following string routines take as many as four different forms: strxxx,
strxxxl, strxxxm, and strxxxlm. These routines differ in how they store
the destination string into memory and where they obtain their source strings.

Routines of the form strxxx generally expect a single source string address
in ES:DI or a source and destination string in ES:DI & DX:SI. If these
routines produce a string, they generally store the result into the buffer
pointed at by ES:DI upon entry. They return with ES:DI pointing at the
first character of the destination string.

Routines of the form strxxxl have a "literal source string". A literal
source string follows the call to the routine in the code stream. E.g.,

strcatl
db"Add this string to ES:DI",0

Routines of the form strxxxm automatically allocate storage for a source
string on the heap and return a pointer to this string in ES:DI.

Routines of the form strxxxlm have a literal source string in the code
stream and allocate storage for the destination string on the heap.



Routine: Strcpy (l)
--------------------

Category: String Handling Routine

Registers on Entry: ES:DI - pointer to source string (Strcpy only)
CS:RET - pointer to source string (Strcpy1 only)
DX:SI - pointer to destination string


Registers on return: ES:DI - points at the destination string


Flags affected: None


Example of Usage:
mov dx, seg Dest
mov si, offset Dest
mov di, seg Source
mov es, di
mov si, offset Source
Strcpy

mov dx, seg Dest
mov si, offset Dest
Strcpyl
db "String to copy",0


Description: Strcpy is used to copy a zero-terminated string from one
location to another. ES:DI points at the source string,
DX:SI points at the destination address. Strcpy copies all
bytes, up to and including the zero byte, from the source
address to the destination address. The target buffer must
be large enough to hold the string. Strcpy performs no error
checking on the size of the destination buffer.

Strcpyl copies the zero-terminated string immediately following
the call instruction to the destination address specified by
DX:SI. Again, this routine expects you to ensure that the
taraget buffer is large enough to hold the result.

Note: There are no "Strcpym" or "Strcpylm" routines. The
reason is simple: "StrDup" and "StrDupl" provide these functions
using names which are familiar to MSC and Borland C users.

Include: stdlib.a or strings.a


Routine: StrDup (l)
--------------------

Category: String Handling Routine

Register on entry: ES:dI - pointer to source string (StrDup
only). CS:RET - Pointer to source string
(StrDupl only).

Register on return: ES:DI - Points at the destination string
allocated on heap. Carry=0 if operation
successful. Carry=0 if insufficient
memory for new string.

Flags affected: Carry flag

Example of usage:
StrDupl
db "String for StrDupl",0
jc MallocError
mov word ptr Dest1, di
mov word ptr Dest1+2, es ;create another
;copy of this
;string. Note
;that es:di points
;at Dest1 upon
;entry to StrDup,
;but it points at
;the new string on
;exit
StrDup
jc MallocError
mov word ptr Dest2, di
mov word ptr Dest2+2, es


Description: StrDup and StrDupl duplicate strings. You pass them
a pointer to the string (in es:di for strdup, via
the return address for strdupl) and they allocate
sufficient storage on the heap for a copy of this
string. Then these two routines copy their source
strings to the newly allocated storage and return
a pointer to the new string in ES:DI.


Include: stdlib.a or strings.a


Routine: Strlen
----------------

Category: String Handling Routine

Registers on entry: ES:DI - pointer to source string.

Register on return: CX - length of specified string.

Flags Affected: None

Examples of Usage:
les di, String
strlen
mov sl, cx
printf
db "Length of '%s' is %d\n",0
dd String, sl


Description: Strlen computes the length of the string whose address
appears in ES:DI. It returns the number of characters
up to, but not including, the zero terminating byte.

Include: stdlib.a or strings.a


Routine: Strcat (m,l,ml)
-------------------------

Category: String Handling Routine

Registers on Entry: ES:DI- Pointer to first string
DX:SI- Pointer to second string (Strcat and Strcatm only)


Registers on Return: ES:DI- Pointer to new string (Strcatm and Strcatml only)

Flags Affected: Carry = 0 if no error
Carry = 1 if insufficient memory (Strcatm and Strcatml
only)


Example of Usage: les DI, String1
mov DX, seg String2
lea SI, String2
Strcat ; String1 <- String1 + String2

les DI, String1
Strcatl ; String1 <- String1 +
db "Appended String",0 ; "Appended String",0


les DI, String1
mov DX, seg String2
lea SI, String2
Strcatm ; NewString <- String1 + String2
puts
free

les DI, String1
Strcatml ; NewString <- String1 +
db "Appended String",0 ; "Appended String",0
puts
free


Description: These routines concatenate two strings together. They differ
mainly in the location of their source and destination operands.

Strcat concatenates the string pointed at by DX:SI to the end of
the string pointed at by ES:DI in memory. Both strings must be
zero-terminated. The buffer pointed at by ES:DI must be large
enough to hold the resulting string. Strcat does NOT perform
bounds checking on the data.

( continued on next page )







Routine: Strcat (m,l,ml) ( continued )
-----------------------------------------


Strcatm computes the length of the two strings pointed at by ES:DI
and DX:SI and attempts to allocate this much storage on the heap.
If it is not successful, Strcatm returns with the Carry flag set,
otherwise it copies the string pointed at by ES:DI to the heap,
concatenates the string DX:SI points at to the end of this string
on the heap, and returns with the Carry flag clear and ES:DI
pointing at the new (concatenated) string on the heap.

Strcatl and Strcatml work just like Strcat and Strcatm except you
supply the second string as a literal constant immediately AFTER
the call rather than pointing DX:SI at it (see examples above).


Include: stdlib.a or strings.a


Routine: Strchr
----------------

Category: String Handling Routine

Register on entry: ES:DI- Pointer to string.
AL- Character to search for.

Register on return: CX- Position (starting at zero)
where Strchr found the character.

Flags affected: Carry=0 if Strchr found the character.
Carry=1 if the character was not present
in the string.

Example of usage:
les di, String
mov al, Char2Find
Strchr
jc NotPresent
mov CharPosn, cx


Description: Strchr locates the first occurrence of a character within a
string. It searches through the zero-terminated string pointed
at by es:di for the character passed in AL. If it locates the
character, it returns the position of that character to the CX
register. The first character in the string corresponds to the
location zero. If the character is not in the string, Strchr
returns the carry flag set. CX's value is undefined in that
case. If Strchr locates the character in the string, it
returns with the carry clear.


Include: stdlib.a or strings.a


Routine: Strstr (l)
--------------------

Category: String Handling Routine

Register on entry: ES:DI - Pointer to string.
DX:SI - Pointer to substring(strstr).
CS:RET - Pointer to substring (strstrl).

Register on return: CX - Position (starting at zero)
where Strstr/Strstrl found the
character. Carry=0 if Strstr/
Strstrl found the character.
Carry=1 if the character was not
present in the string.


Flags affected: Carry flag

Example of usage :
les di, MainString
lea si, Substring
mov dx, seg Substring
Strstr
jc NoMatch
mov i, cx
printf
db "Found the substring '%s' at location %i\n",0
dd Substring, i


Description: Strstr searches for the position of a substring
within another string. ES:DI points at the
string to search through, DX:SI points at the
substring. Strstr returns the index into ES:DI's
string where DX:SI's string is found. If the
string is found, Strstr returns with the carry
flag clear and CX contains the (zero based) index
into the string. If Strstr cannot locate the
substring within the string ES:DI points at, it
returns the carry flag set. Strstrl works just
like Strstr except it excepts the substring to
search for immediately after the call instruction
(rather than passing this address in DX:SI).


Include: stdlib.a or strings.a


Routine: Strcmp (l)
--------------------

Category: String Handling Routine

Registers on entry: ES:DI contains the address of the first string
DX:SI contains the address of the second string (strcmp)
CS:RET (contains the address of the substring (strcmpl)

Register on return: CX (contains the position where the two strings differ)

Flags affected: Carry flag and zero flag (string1 > string2 if C + Z = 0)
(string1 < string2 if C = 1)

Example of Usage:
les di, String1
mov dx, seg String2
lea si, String2
strcmp
jaOverThere

les di, String1
strcmpl
db "Hello",0
jbe elsewhere



Description: Strcmp compares the first strings pointed by ES:DI with
the second string pointed by DX:SI. The carry and zero flag
will contain the corresponding result. So unsigned branch
instructions such as JA or JB is recommended. If string1
equals string2, strcmp will return with CX containing the
offset of the zero byte in the two strings.

Strcmpl compares the first string pointed by ES:DI with
the substring pointed by CS:RET. The carry and zero flag
will contain the corresponding result. So unsigned branch
instructions such as JA or JB are recommended. If string1
equals to the substring, strcmp will return with CX
containing the offset of the zero byte in the two strings.

Include: stdlib.a or strings.a


Routine: Strupr (m)
--------------------

Category: String Handling Routine
Conversion Routine

Register on entry: ES:DI (contains the pointer to input string)

Register on return: ES:DI (contains the pointer to input string
with characters converted to upper case)
Note: struprm allocates storage for a new
string on the heap and returns the pointer
to this routine in ES:DI.

Flags affected: Carry = 1 if memory allocation error (Struprm only).

Example of Usage:
les di, lwrstr1
strupr
puts

mov di, seg StrWLwr
moves, di
leadi, StrWLwr
struprm
puts
free


Description: Strupr converts the input string pointed by ES:DI to
upper case. It will actually modify the string you pass
to it.

Struprm first makes a copy of the string on the heap and
then converts the characters in this new string to upper
case. It returns a pointer to the new string in ES:DI.

Include: stdlib.a or strings.a


Routine: Strlwr (m)
--------------------

Category: String Handling Routine
Conversion Routine

Register on entry: ES:DI (contains the pointer to input string)

Register on return: ES:DI (contains the pointer to input string
with characters converted to lower case).

Flags affected: Carry = 1 if memory allocation error (strlwrm only)


Example of Usage:
les di, uprstr1
strlwr
puts

mov di, seg StrWLwr
moves, di
leadi, StrWLwr
strlwrm
puts
free




Description: Strlwr converts the input string pointed by ES:DI to
lower case. It will actually modify the string you pass
to it.

Strlwrm first copies the characters onto the heap and then
returns a pointer to this string after converting all the
alphabetic characters to lower case.


Include: stdlib.a or strings.a



Routine: Strset (m)
--------------------

Category: String Handling Routine

Register on entry: ES:DI contains the pointer to input string (StrSet only)
AL contains the character to copy
CX contains number of characters to allocate for
the string (Strsetm only)

Register on return: ES:DI pointer to newly allocated string (Strsetm only)

Flags affected: Carry set if memory allocation error (Strsetm only)

Example of Usage:
les di, string1
moval, " ";Blank fill string.
Strset

mov cx, 32
moval, "*";Create a new string w/32
Strsetm; asterisks.
puts
free


Description: Strset overwrites the data on input string pointed by
ES:DI with the character on AL.

Strsetm creates a new string on the heap with the number
of characters specified in CX. All characters in the string
are initialized with the value in AL.

Include: stdlib.a or strings.a


Routine: Strspan (l)
---------------------

Category: String Handling Routine

Registers on Entry: ES:DI - Pointer to string to scan
DX:SI - Pointer to character set (Strspan only)
CS:RET- Pointer to character set (Strspanl only)

Registers on Return: CX- First position in scanned string which does not
contain one of the characters in the character set

Flags Affected: None

Example of Usage:
les DI, String
mov DX, seg CharSet
lea SI, CharSet
Strspan ; find first position in String with a
mov i, CX ; char not in CharSet
printf
db "The first char which is not in CharSet "
db "occurs at position %d in String.\n",0
dd i

les DI, String
Strspanl ; find first position in String which
db "aeiou",0 ; is not a vowel
mov j, CX
printf
db "The first char which is not a vowel "
db "occurs at position %d in String.\n",0
dd j


Description: Strspan(l) scans a string, counting the number of characters which
are present in a second string (which represents a character set).
ES:DI points at a zero-terminated string of characters to scan.
DX:SI (strspan) or CS:RET (strspanl) points at another zero-
terminated string containing the set of characters to compare
against. The position of the first character in the string
pointed to by ES:DI which is NOT in the character set is returned.
If all the characters in the string are in the character set, the
position of the zero-terminating byte will be returned.

Although strspan and (especially) strspanl are very compact and
convenient to use, they are not particularly efficient. The
character set routines provide a much faster alternative at the
expense of a little more space.


Include: stdlib.a or strings.a


Routine: Strcspan, Strcspanl
-----------------------------

Category: String Handling Routine

Registers on Entry: ES:DI - Pointer to string to scan
DX:SI - Pointer to character set (Strcspan only)
CS:RET- Pointer to character set (Strcspanl only)

Registers on Return: CX- First position in scanned string which contains one
of the characters in the character set

Flags Affected: None

Example of Usage:
les DI, String
mov DX, seg CharSet
lea SI, CharSet
Strcspan ; find first position in String with a
mov i, CX ; char in CharSet
printf
db "The first char which is in CharSet "
db "occurs at position %d in String.\n",0
dd i

les DI, String
Strcspanl ; find first position in String which
db "aeiou",0; is a vowel.
mov j, CX
printf
db "The first char which is a vowel occurs "
db "at position %d in String.\n",0
dd j


Description: Strcspan(l) scans a string, counting the number of characters
which are NOT present in a second string (which represents a
character set). ES:DI points at a zero-terminated string of
characters to scan. DX:SI (strcspan) or CS:RET (strcspanl) points
at another zero-terminated string containing the set of characters
to compare against. The position of the first character in the
string pointed to by ES:DI which is in the character set is
returned. If all the characters in the string are not in the
character set, the position of the zero-terminating byte will be
returned.

Although strcspan and strcspanl are very compact and convenient to
use, they are not particularly efficient. The character set
routines provide a much faster alternative at the expense of a
little more space.

Include: stdlib.a or strings.a


Routine: StrIns (m,l,ml)
-------------------------

Category: String Handling Routine

Registers on Entry: ES:DI - Pointer to destination string (to insert into)
DX:SI - Pointer to string to insert
(StrIns and StrInsm only)
CX - Insertion point in destination string

Registers on Return: ES:DI - Pointer to new string (StrInsm and StrInsml only)

Flags Affected: Carry = 0 if no error
Carry = 1 if insufficient memory
(StrInsm and StrInsml only)


Example of Usage:
les DI, DestStr
mov DX, word ptr SrcStr+2
mov SI, word ptr SrcStr
mov CX, 5
StrIns ; Insert SrcStr before the 6th char of DestStr

les DI, DestStr
mov CX, 2
StrInsl ; Insert "Hello" before the 3rd char of DestStr
db "Hello",0

les DI, DestStr
mov DX, word ptr SrcStr+2
mov SI, word ptr SrcStr
mov CX, 11
StrInsm ; Create a new string by inserting SrcStr
; before the 12th char of DestStr
puts
putcr
free


Description: These routines insert one string into another string. ES:DI
points at the string into which you want to insert another. CX
contains the position (or index) where you want the string
inserted. This index is zero-based, so if CX contains zero, the
source string will be inserted before the first character in the
destination string. If CX contains a value larger than the size
of the destination string, the source string will be appended to
the destination string.

StrIns inserts the string pointed at by DX:SI into the string
pointed at by ES:DI at position CX. The buffer pointed at by
ES:DI must be large enough to hold the resulting string. StrIns
does NOT perform bounds checking on the data.

( continued on next page )


Routine: StrIns (m,l,ml) ( continued )
-----------------------------------------

StrInsm does not modify the source or destination strings, but
instead attempts to allocate a new buffer on the heap to hold the
resulting string. If it is not successful, StrInsm returns with
the Carry flag set, otherwise the resulting string is created and
its address is returned in the ES:DI registers.

StrInsl and StrInsml work just like StrIns and StrInsm except you
supply the second string as a literal constant immediately AFTER
the call rather than pointing DX:SI at it (see examples above).



Routine: StrDel, StrDelm
-------------------------

Category: String Handling Routine

Registers on Entry: ES:DI - pointer to string
CX - deletion point in string
AX - number of characters to delete

Registers on return: ES:DI - pointer to new string (StrDelm only)

Flags affected: Carry = 1 if memory allocation error, 0 if okay
(StrDelm only).

Example of Usage:
les di, Str2Del
mov cx, 3 ; Delete starting at 4th char
mov ax, 5 ; Delete five characters
StrDel ; Delete in place

les di, Str2Del2
mov cx, 5
mov ax, 12
StrDelm
puts
free


Description: StrDel deletes characters from a string. It works by computing
the beginning and end of the deletion point. Then it copies all
the characters from the end of the deletion point to the end of
the string (including the zero byte) to the beginning of the
deletion point. This covers up (thereby effectively deleting)
the undesired characters in the string.

Here are two degenerate cases to worry about -- 1) when you
specify a deletion point which is beyond the end of the string;
and 2) when the deletion point is within the string but the
length of the deletion takes you beyond the end of the string.
In the first case StrDel simply ignores the deletion request. It
does not modify the original string. In the second case,
StrDel simply deletes everything from the deletion point to the
end of the string.

StrDelm works just like StrDel except it does not delete the
characters in place. Instead, it creates a new string on the
heap consisting of the characters up to the deletion point and
those following the characters to delete. It returns a pointer
to the new string on the heap in ES:DI, assuming that it
properly allocated the storage on the heap.

Include: stdlib.a or strings.a


Routine: StrRev, StrRevm
-------------------------

Author: Michael Blaszczak (.B ekiM)

Category: String Handling Routine

Registers on Entry: ES:DI - pointer to string

Registers on return: ES:DI - pointer to new string (StrRevm only).

Flags affected: Carry = 1 if memory allocation error, 0 if okay
(StrRevm only).

Example of Usage:

Description: StrRev reverses the characters in a string. StrRev reverses,
in place, the characters in the string that ES:SI points at.
StrRevm creates a new string on the heap (which contains the
characters in the string ES:DI points at, only reversed) and
returns a pointer to the new string in ES:DI. If StrRevm
cannot allocate sufficient memory for the string, it returns
with the carry flag set.


Include: stdlib.a or strings.a


Routine: ToHex
---------------

Category: String Handling Routine/ Conversion Routine

Registers on Entry: ES:DI - pointer to byte array
BX- memory base address for bytes
CX- number of entries in byte array

Registers on return: ES:DI - pointer to Intel Hex format string.

Flags affected: Carry = 1 if memory allocation error, 0 if okay


Example of Usage:

movbx, 100h;Put data at address 100h in hex file.
movcx, 10h;Total of 16 bytes in this array.
lesdi, Buffer;Pointer to data bytes
ToHex;Convert to Intel HEX string format.
puts;Print it.

Description:

ToHex converts a stream of binary values to Intel Hex format. Intel HEX format
is a common ASCII data interchange format for binary data. It takes the
following form:

: BB HHLL RR DDDD...DDDD SS

(Note:spaces were added for clarity, they are not actually present in the
hex string)

BB is a pair of hex digits which represent the number of data bytes (The DD
entries) and is the value passed in CX.

HHLL is the hexadecimal load address for these data bytes (passed in BX).

RR is the record type. ToHex always produces data records with the RR field
containing "00". If you need to output other field types (usually just an
end record) you must create that string yourself. ToHex will not do it.

DD...DD is the actual data in hex form. This is the number of bytes specified
in the BB field.

SS is the two's complement of the checksum (which is the sum of the binary
values of the BB, HH, LL, RR, and all DD fields).

This routine allocates storage for the string on the heap and returns a pointer
to that string in ES:DI.

Include: stdlib.a or strings.a


Memory Management Routines
--------------------------

The stdlib memory management routines let you dynamically allocate storage on
the heap. These routines are somewhat similar to those provided by the "C"
programming language. However, these routines do not perform garbage
collection, as this would introduce too many restrictions and have a very
adverse effect on speed.

The following paragraph gives a description of how the memory management
routines work. These routines may be updated in future revisions, however,
so you should never make assumptions about the structure of the memory
management record (described below) or else your code may not work on the
next revision.

The allocation/deallocation routines should be fairly fast. Malloc and free
use a modified first/next fit algorithm which lets the system quickly find a
memory block of the desired size without undue fragmentation problems (average
case). The memory manager data structure has an overhead of eight bytes
(meaning each malloc operation requires at least eight more bytes than you ask
for) and a granularity of 16 bytes. The overhead (eight bytes) per allocated
block may seem rather high, but that is part of the price to pay for faster
malloc and free routines. All pointers are far pointers and each new item is
allocated on a paragraph boundary. The current memory manager routines always
allocate (n+8) bytes, rounding up to the next multiple of 16 if the result is
not evenly divisible by sixteen. The first eight bytes of the structure are
used by the memory management routines, the remaining bytes are available for
use by the caller (malloc, et. al., return a pointer to the first byte beyond
the memory management overhead structure).




Routine: MemInit
-----------------

Category: Memory Management Routine

Registers on Entry: DX - number of paragraphs to reserve

Globals Affected: zzzzzzseg - segment name of the last segment in your
program
PSP - public word variable which holds the PSP value
for your program

Registers on return: CX - number of paragraphs actually reserved by MemInit

Flags affected: Carry = 0 if no error.
Carry = 1 if error; AX contains DOS error code.


Example of Usage:
; Don't forget to set up PSP
; and zzzzzzseg before calling
; MemInit
mov dx, dx ; Allocate all available RAM
MemInit
jc MemoryError ; CX contains the number of
; paragraphs actually
; allocated


Description: This routine initializes the memory manager system. You must
call it before using any routines which call any of the memory
manager procedures (since a good number of the stdlib routines
call the memory manager, you should get in the habit of always
calling this routine.) The system will "die a horrible death"
if you call a memory manager routine (like malloc) without first
calling MemInit.

This routine expects you to define (and set up) two global
names: zzzzzzseg and PSP. "zzzzzzseg" is a dummy segment which
must be the name of the very last segment defined in your
program. MemInit uses the name of this segment to determine the
address of the last byte in your program. If you do not
declare this segment last, the memory manager will overwrite
anything which follows zzzzzzseg. The "shell.asm" file
provides you with a template for your programs which properly
defines this segment.

PSP should be a word variable which contains the program segment
prefix value for your program. MS-DOS passes the PSP value to
your program in the DS and ES registers. You should save this
value in the PSP variable. Don't forget to make PSP a public
symbol in your main program's source file. The "shell.asm" file
demonstrates how to properly set up this value.

The DX register contnains the number of 16-byte paragraphs you
want to reserve for the heap. If DX contains zero, MemInit will
allocate all of the available memory to the heap. If your
program is going to allow the user to run a copy of the command
interpreter, or if your program is going to EXEC some other
program, you should not allocate all storage to the heap.
Instead, you should reserve some memory for those programs.
By setting DX to some value other than zero, you can tell MemInit
how much memory you want to reserve for the heap. All left over
memory will be available for other system (or program) use.
If the value in DX is larger than the amount of available RAM,
MemInit will split the available memory in half and reserve half
for the heap leaving the other half unallocated. If you want to
force this situation (to leave half available memory for other
purposes), simply load DX with 0FFFFH before calling MemInit.
There will never be this much memory available, so this will
force MemInit to split the available RAM between the heap and
unallocated storage.

On return from MemInit, the CX register contains the number of
paragraphs actually allocated. You can use this value to see if
MemInit has actually allocated the number of paragraphs you
requested. You can also use this value to determine how much
space is available when you elect to split the free space
between the heap and the unallocated portions.

If all goes well, this routine returns the carry flag clear.
If a DOS memory manager error occurs, this routine returns the
carry flag set and the DOS error code in the AX register.


Include: stdlib.a or memory.a


Routine: Malloc
----------------

Category: Memory Management Routine

Registers on Entry: CX - number of bytes to reserve

Registers on return: CX - number of bytes actually reserved by Malloc
ES:DI - ptr to 1st byte of memory allocated by Malloc

Flags affected: Carry=0 if no error.
Carry=1 if insufficient memory.

Example of Usage:
mov cx, 256
Malloc
jnc GoodMalloc
print db "Insufficient memory to continue.",cr,lf,0
jmp Quit
GoodMalloc: mov es:[di], 0 ;Init string to NULL


Description: Malloc is the workhorse routine you use to allocate a block of
memory. You give it the number of bytes you need and if it
finds a block large enough, it will allocate the requested
amount and return a pointer to that block.

Most memory managers require a small amount of overhead for each
block they allocate. Stdlib's (current) memory manager requires
an overhead of eight bytes. Furthermore, the grainularity is 16
bytes. This means that Malloc always allocates blocks of memory
in paragraph multiples. Therefore, Malloc may actually reserve
more storage than you specify. Therefore, the value returned in
CX may be somewhat greater than the requested value. By setting
the minimum allocation size to a paragraph, however, the
overhead is reduced and the speed of Malloc is improved by a
considerable amount.

Stdlib's memory management does not do any garbage collection.
Doing so would place too many demands on Malloc's users.
Therefore, it is quite possible for you to fragment memory with
multiple calls to maloc, realloc, and free. You could wind up in
a situation where there is enough free memory to satisfy your
request, but there isn't a single contiguous block large enough
for the request. Malloc treats this as an insufficient memory
error and returns with the carry flag set.

If Malloc cannot allocate a block of the requested size, it
returns with the carry flag set. In this situation, the contents
of ES:DI is undefined. Attempting to dereference this pointer
will produce erratic and, perhaps, disasterous results.

Include: stdlib.a or memory.a


Routine: Realloc
-----------------

Category: Memory Management Routine

Registers on Entry: CX - number of bytes to reserve
ES:DI - pointer to block to reallocate.

Registers on return: CX - number of bytes actually reserved by Realloc.
ES:DI - pointer to first byte of memory allocated by
Realloc.

Flags affected: Carry = 0 if no error.
Carry = 1 if insufficient memory.

Example of Usage:
movcx, 1024;Change block size to 1K
lesdi, CurPtr;Get address of block into ES:DI
realloc
jcBadRealloc
movword ptr CurPtr, di
movword ptr CurPtr+2, es


Description: Realloc lets you change the size of an allocated block in the
heap. It allows you to make the block larger or smaller.
If you make the block smaller, Realloc simply frees (returns
to the heap) any leftover bytes at the end of the block. If
you make the block larger, Realloc goes out and allocates a
block of the requested size, copies the bytes form the old
block to the beginning of the new block (leaving the bytes at
the end of the new block uninitialized)), and then frees the
old block.


Include: stdlib.a or memory.a


Routine: Free
--------------

Category: Memory Management Routine

Registers on Entry: ES:DI - pointer to block to deallocate

Registers on return: None

Flags affected: Carry = 0 if no error.
Carry = 1 if ES:DI doesn't point at a Free block.

Example of Usage:
les di, HeapPtr
Free

Description: Free (possibly) deallocates storage allocated on the heap by
malloc or Realloc. Free returns this storage to heap so other
code can reuse it later. Note, however, that Free doesn't
always return storage to the heap. The memory manager data
structure keeps track of the number of pointers currently
pointing at a block on the heap (see DupPtr, below). If you've
set up several pointers such that they point at the same block,
Free will not deallocate the storage until you've freed all of
the pointers which point at the block.

Free usually returns an error code (carry flag = 1) if you
attempt to Free a block which is not currently allocated or if
you pass it a memory address which was not returned by malloc
(or Realloc). By no means is this routine totally robust.
If you start calling free with arbitrary pointers in es:di
(which happen to be pointing into the heap) it is possible,
under certain circumstances, to confuse Free and it will attempt
to free a block it really should not.

This problem could be solved by adding a large amount of extra
code to the free routine, but it would slow it down considerably.
Therefore, a little safety has been sacrificed for a lot of
speed. Just make sure your code is correct and everything will
be fine!


Include: stdlib.a or memory.a


Routine: DupPtr
----------------

Category: Memory Manager Routine

Registers on Entry: ES:DI - pointer to block

Registers on return: None

Flags affected: Carry = 0 if no error.
Carry = 1 if es:di doesn't point at a free block.

Example of Usage:
les di, Ptr
DupPtr


Description: DupPtr increments the pointer count for the block at the
specifiied address. Malloc sets this counter to one. Free
decrements it by one. If free decrements the value and it
becomes zero, free will release the storage to the heap for
other use. By using DupPtr you can tell the memory manager
that you have several pointers pointing at the same block
and that it shouldn't deallocate the storage until you free
all of those pointers.


Include: stdlib.a or memory.a


Routine: IsInHeap
------------------

Category: Memory Management Routine

Registers on Entry: ES:DI - pointer to a block

Registers on return: None

Flags affected: Carry = 0 if ES:DI is a valid pointer.
Carry = 1 if not.

Example of Usage:
lesdi, MemPtr
IsInHeap
jcNotInHeap

Description: This routine lets you know if es:di contains the address of
a byte in the heap somewhere. It does not tell you if es:di
contains a valid pointer returned by malloc (see IsPtr, below).
For example, if es:di contains the address of some particular
element of an array (not necessarily the first element)
allocated on the heap, IsInHeap will return with the carry clear
denoting that the es:di points somewhere in the heap. Keep in
mind that calling this routine does not validate the pointer;
it could be pointing at a byte which is part of the memory
manager data structure rather than at actual data (since the
memory manager maintains that informatnion within the
bounds of the heap). This routine is mainly useful for seeing
if something is allocated on the heap as opposed to somewhere
else (like your code, data, or stack segment).


Include: stdlib.a or memory.a


Routine: IsPtr
---------------

Category: Memory Management Routine

Registers on Entry: ES:DI - pointer to block

Registers on return: None

Flags affected: Carry = 0 if es:di is a valid pointer.
Carry = 1 if not.

Example of Usage:
lesdi, MemPtr
IsPtr
jcNotAPtr



Description: IsPtr is much more specific than IsInHeap. This routine returns
the carry flag clear if and only if es:di contains the address
of a properly allocated (and currently allocated) block on the
heap. This pointer must be a value returned by Malloc, Realloc,
or DupPtr and that block must be currently allocated for IsPtr
to return the carry flag clear.


Include: stdlib.a or memory.a


Character Set Routines
----------------------

The character set routines let you deal with groups of characters as a set
rather than a string. A set is an unordered collection of objects where
membership (presence or absence) is the only important quality. The stdlib
set routines were designed to let you quickly check if an ASCII character is
in a set, to quickly add characters to a set or remove characters from a set.
These operations are the ones most commonly used on character sets. The
other operations (like union, intersection, difference, etc.) are useful, but
are not as popular as the former routines. Therefore, the data structure
has been optimized for sets to handle the membership and add/delete operations
at the slight expense of the others.

Character sets are implemented via bit vectors. A "1" bit means that an item
is present in the set and a "0" bit means that the item is absent from the
set. The most common implementation of a character set is to use thirty-two
consecutive bytes, eight bytes per, giving 256 bits (one bit for each char-
acter in the character set). While this makes certain operations (like
assignment, union, intersection, etc.) fast and convenient, other operations
(membership, add/remove items) run much slower. Since these are the more
important operations, a different data structure is used to represent sets.
A faster approach is to simply use a byte value for each item in the set.
This offers a major advantage over the thirty-two bit scheme: for operations
like membership it is very fast (since all you have got to do is index into
an array and test the resulting value). It has two drawbacks: first, oper-
ations like set assignment, union, difference, etc., require 256 operations
rather than thirty-two; second, it takes eight times as much memory.

The first drawback, speed, is of little consequence. You will rarely use the
the operations so affected, so the fact that they run a little slower will be
of little consequence. Wasting 224 bytes is a problem, however. Especially
if you have a lot of character sets.

The approach used here is to allocate 272 bytes. The first eight bytes con-
tain bit masks, 1, 2, 4, 8, 16, 32, 64, 128. These masks tell you which bit
in the following 264 bytes is associated with the set. This facilitates
putting eight sets into 272 bytes (34 bytes per character set). This provides
almost the speed of the 256-byte set with only a two byte overhead. In the
stdlib.a file there is a macro that lets you define a group of character
sets: set. The macro is used as follows:

set set1, set2, set3, ... , set8

You must supply between one and eight labels in the operand field. These are
the names of the sets you want to create. The set macro automatically
attaches these labels to the appropriate mask bytes in the set. The actual
bit patterns for the set begin eight bytes later (from each label). There-
fore, the byte corresponding to chr(0) is staggered by one byte for each
set (which explains the other eight bytes needed above and beyond the 256
required for the set). When using the set manipulation routines, you should
always pass the address of the mask byte (i.e., the seg/offset of one of the
labels above) to the particular set manipulation routine you are using.
Passing the address of the structure created with the macro above will
reference only the first set in the group.

Note that you can use the set operations for fast pattern matching appli-
cations. The set membership operation for example, is much faster that the
strspan routine found in the string package. Proper use of character sets
can produce a program which runs much faster than some of the equivalent
string operations.


Routine: Createsets
--------------------

Category: Character Set Routine

Registers on Entry: no parameters passed

Registers on return: ES:DI - pointer to eight sets

Flags affected: Carry = 0 if no error. Carry = 1 if insufficient
memory to allocate storage for sets.

Example of Usage:
Createsets
jc NoMemory
mov word ptr SetPtr, di
mov word ptr SetPtr+2, es

Description: Createsets allocates 272 bytes on the heap. This is sufficient
room for eight character sets. It then initializes the first
eight bytes of this storage with the proper mask values for
each set. Location es:0[di] gets set to 1, location es:1[di]
gets 2, location es:2[di] gets 4, etc. The Createsets routine
also initializes all of the sets to the empty set by clearing
all the bits to zero.

Include: stdlib.a or charsets.a


Routine: EmptySet
------------------

Category: Character Set Routine

Registers on Entry: ES:DI - pointer to first byte of desired set

Registers on return: None

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 3 ; Point at 4th set in group.
Emptyset


Description: Emptyset clears out the bits in a character set to zero
(thereby setting it to the empty set). Upon entry, es:di must
point at the first byte of the character set you want to clear.
Note that this is not the address returned by Createsets. The
first eight bytes of a character set structure are the
addresses of eight different sets. ES:DI must point at one of
these bytes upon entry into Emptyset.

Include: stdlib.a or charsets.a


Routine: Rangeset
------------------

Category: Character Set Routine

Registers on entry: ES:DI (contains the address of the first byte of the set)
AL (contains the lower bound of the items)
AH (contains the upper bound of the items)

Registers on return: None

Flags affected: None

Example of Usage:
lea di, SetPtr
add di, 4
mov al, 'A'
mov ah, 'Z'
rangeset


Description: This routine adds a range of values to a set with ES:DI as the
pointer to the set, AL as the lower bound of the set, and
AH as the upper bound of the set (AH has to be greater than
AL, otherwise, there will an error).

Include: stdlib.a or charsets.a


Routine: Addstr (l)
--------------------

Category: Character Set Routine

Registers on Entry: ES:DI- pointer to first byte of desired set
DX:SI- pointer to string to add to set (Addstr only)
CS:RET-pointer to string to add to set (Addstrl only)

Registers on Return: None

Flags Affected: None

Example of Usage:
les di, SetPtr
add di, 1 ;Point at 2nd set in group.
mov dx, seg CharStr ;Pointer to string
lea si, CharStr ; chars to add to set.
addstr ;Union in these characters.
;
les di, SetPtr ;Point at first set in group.
addstrl
db "AaBbCcDdEeFf0123456789",0
;


Description: Addstr lets you add a group of characters to a set by
specifying a string containing the characters you want in
the set. To Addstr you pass a pointer to a zero-terminated
string in dx:si. Addstr will add (union) each character
from this string into the set.

Addstrl works the same way except you pass the string as
a literal string constant in the code stream rather than
via ES:DI.

Include: stdlib.a or charsets.a


Routine: Rmvstr (l)
--------------------


Category: Character Set Routine


Registers on entry: ES:DI contains the address of first byte of a set
DX:SI contains the address of string to be removed
from a set (Rmvstr only)
CS:RET pointer to string to add to set (Rmvstrl only)



Registers on return: None


Flags affected: None


Example of Usage:
les di, SetPtr
mov dx, seg CharStr
lea si, CharStr
rmvstr

mov dx, seg CharStr
lea si, CharStr
rmvstrl
db "ABCDEFG",0


Description: This routine is to remove a string from a set with ES:DI
pointing to its first byte, and DX:SI pointing to the
string to be removed from the set.

For Rmvstrl, the string of characters to remove from the
set follows the call in the code stream.

Include: stdlib.a or charsets.a


Routine: AddChar
-----------------

Category: Character Set Routine

Registers on Entry: ES:DI- pointer to first byte of desired set
AL- character to add to the set

Registers on Return: None

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 1 ;Point at 2nd set in group.
mov al, Ch2Add ;Character to add to set.
addchar


Description: AddChar lets you add a single character (passed in AL)
to a set.

Include: stdlib.a or charsets.a


Routine: Rmvchar
-----------------

Category: Character Set Routine

Registers on entry: ES:DI (contains the address of first byte of a set)
AL (contains the character to be removed)

Registers on return: None

Flags affected: None

Example of Usage:
lea di, SetPtr
add di, 7;Point at eighth set in group.
mov al, Ch2Rmv
Rmvchar

Description: This routine removes the character in AL from a set.
ES:SI points to the set's mask byte. The corresponding
bit in the set is cleared to zero.

Include: stdlib.a or charsets.a


Routine: Member
----------------

Category: Character Set Routine

Registers on entry: ES:DI (contains the address of first byte of a set)
AL (contains the character to be compared)

Registers on return: None

Flags affected: Zero flag (Zero = 1 if the character is in the set
Zero = 0 if the character is not in the set)

Example of Usage:
les di, SetPtr
add di, 1
mov al, 'H'
member
je IsInSet


Description: Member is used to find out if the character in AL is in a set
with ES:DI pointing to its mask byte. If the character is in
the set, the zero flag is set to 1. If not, the zero flag is
set to zero.

Include: stdlib.a or charsets.a


Routine: CopySet
-----------------

Category: Character Set Routine

Register on entry: ES:DI- pointer to first byte of destination set.
DX:SI- pointer to first byte of source set.

Register on Return: None

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 7 ;Point at 8th set in group.
mov dx, seg SetPtr2 ;Point at first set in group.
lea si, SetPtr2
copyset


Description: CopySet copies the items from one set to another. This is a
straight assignment, not a union operation. After the
operation, the destination set is identical to the source set,
both in terms of the element present in the set and absent
from the set.


Include: stdlib.a or charsets.a


Routine: SetUnion
------------------

Category: Character Set Routine

Register on entry: ES:DI - pointer to first byte of destination set.
DX:SI - pointer to first byte of source set.

Register on return: None

Flags affected: None

Example of Usage: les di, SetPtr
add di, 7 ;point at 8th set in group.
mov dx, seg SetPtr2 ;point at 1st set in group.
lea si, sSetPtr2
unionset


Description: The SetUnion routine computes the union of two sets.
That is, it adds all of the items present in a source set
to a destination set. This operation preserves items
present in the destination set before the SetUnion
operation.

Include: stdlib.a or charsets.a


Routine: SetIntersect
----------------------

Category: Character Set Routine

Register on entry: ES:DI - pointer to first byte of destination set.
DX:SI - pointer to first byte of source set.

Register on return: None

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 7 ;point at 8th set in group.
mov dx, seg SetPtr2 ;point at 1st set in group.
lea si, SetPtr2
setintersect

Description: SetIntersect computes the intersection of two sets, leaving
the result in the destination set. The new set consists
only of those items which previously appeared in
both the source and destination sets.

Include: stdlib.a or charsets.a


Routine: SetDifference
-----------------------

Category: Character Set Routine

Register on entry: ES:DI - pointer to the first byte of destination set.
DX:SI - pointer to the first byte of the source set.

Register on return: None

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 7 ;point at 8th set in group.
mov dx, seg SetPtr2 ;point at 1st set in group.
lea si, SetPtr2
setdifference


Description: SetDifference computes the result of (ES:DI) := (ES:DI) -
(DX:SI). The destination set is left with its original
items minus those items which are also in the source set.

Include: stdlib.a or charsets.a


Routine: Nextitem
------------------

Category: Character Set Routine

Registers on entry: ES:DI (contains the address of first byte of the set)

Registers on return: AL (contains the first item in the set)

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 7;Point at eighth set in group.
nextitem


Description: Nextitem is the routine to search the first character (item)
in the set with ES:DI pointing to its mask byte. AL will
return the character in the set. If the set is empty, AL
will contain zero.

Include: stdlib.a or charsets.a


Routine: Rmvitem
-----------------

Category: Character Set Routine

Registers on entry: ES:DI (contains the address fo first byte of the set)

Registers on return: AL (contains the first item in the set)

Flags affected: None

Example of Usage:
les di, SetPtr
add di, 7
rmvitem

Description: Rmvitem locates the first available item in the set and
removes it with ES:DI pointing to its mask byte. AL will
return the item removed. If the set is empty, AL will
return zero.

Include: stdlib.a or charsets.a



Floating Point Routines
-----------------------

The floating point routines provide a basic floating point package for
80x86 assembly language users. The floating point package deals with
four different floating point formats: IEEE 32-bit, 64-bit, and 80-bit
formats, and an internal 81-bit format. The external formats mostly
support the IEEE standard except for certain esoteric values such as
denormalized numbers, NaNs, infinities, and other such cases.

The package provides two "pseudo-registers", a floating point accumulator
and a floating point operand. It provides routines to load and store these
pseudo-registers from memory operands (using the various formats) and then
all other operations apply to these two operands. All computations use the
internal 81-bit floating point format. The package automatically converts
between the internal format and the external format when loading and storing
values.

Do not write code which assumes the internal format is 81 bits. This format
will change in the near future when I get a chance to add guard bits to
all the computations. If your code assumes 81 bits, it will break at that
point. Besides, there is no reason your code should count on the size of
the internal operations anyway. Stick with the IEEE formats and you'll
be much better off (since your code can be easily upgraded to deal with
numeric coprocessors).

WARNING: These routines have not been sufficiently tested as of 10/10/91.
Use them with care. Report any problems with these routines to Randy Hyde
via the electronic addresses provided in this document or by sending a
written report to UC Riverside. As I get more time, I will further test
these routines and add additional functions to the package.

*** Randy Hyde



Routine: lsfpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a single precision (32-bit) value to load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
lsfpa

Description:LSFPA loads a single precision floating point value into the
internal floating point accumulator. It also converts the
32-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a

Routine: ssfpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a single precision (32-bit) value where
this routine should store the floating point acc.

Registers on return: None

Flags affected: Carry set if conversion error.

Example of Usage:
les di, FPValue
ssfpa

Description:SSFPA stores the floating point accumulator into a single
precision variable in memory (pointed at by ES:DI). It
converts the value from the 81-bit format to the 32-bit
value before storing the result. The 64-bit mantissa used
by the FP package is rounded to 24 bits during the store.
The exponent could be out of range. If this occurs, SSFPA
returns with the carry flag set.

Include:stdlib.a or fp.a


Routine: ldfpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a double precision (64-bit) value to load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
ldfpa

Description:LDFPA loads a double precision floating point value into the
internal floating point accumulator. It also converts the
64-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a

Routine: sdfpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a double precision (64-bit) value where
this routine should store the floating point acc.

Registers on return: None

Flags affected: Carry set if conversion error.

Example of Usage:
les di, FPValue
sdfpa

Description:SDFPA stores the floating point accumulator into a double
precision variable in memory (pointed at by ES:DI). It
converts the value from the 81-bit format to the 64-bit
value before storing the result. The 64-bit mantissa used
by the FP package is rounded to 51 bits during the store.
The exponent could be out of range. If this occurs, SDFPA
returns with the carry flag set.

Include:stdlib.a or fp.a


Routine: lefpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at an extended precision (80-bit) value to
load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
lefpa

Description:LEFPA loads an extended precision floating point value into
the internal floating point accumulator. It also converts the
80-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a


Routine: lefpal
----------------

Category: Floating point Routine

Registers on entry: CS:RET points at an extended precision (80-bit) value to
load

Registers on return: None

Flags affected: None

Example of Usage:
lefpal
dt1.345e-3

Description:LEFPAL loads an extended precision floating point value into
the internal floating point accumulator. It also converts the
80-bit format to the internal 81-bit format used by the
floating point package.

Unlike LEFPA, LEFPAL gets its operand directly from the code
stream. You must follow the call to lefpal with a ten-byte
(80-bit) floating point constant.
Include:stdlib.a or fp.a

Routine: sefpa
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at an extended precision (80-bit) value
where this routine should store the floating point acc.

Registers on return: None

Flags affected: Carry set if conversion error.

Example of Usage:
les di, FPValue
sefpa

Description:SEFPA stores the floating point accumulator into an extended
precision variable in memory (pointed at by ES:DI). It
converts the value from the 81-bit format to the 80-bit
value before storing the result.

The exponent could be out of range. If this occurs, SEFPA
returns with the carry flag set.

Include:stdlib.a or fp.a


Routine: lsfpo
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a single precision (32-bit) value to load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
lsfpo

Description:LSFPA loads a single precision floating point value into the
internal floating point operand. It also converts the
32-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a


Routine: ldfpo
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at a double precision (64-bit) value to load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
ldfpo

Description:LDFPO loads a double precision floating point value into the
internal floating point operand. It also converts the
64-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a


Routine: lefpo
---------------

Category: Floating point Routine

Registers on entry: ES:DI points at an extended precision (80-bit) value to
load

Registers on return: None

Flags affected: None

Example of Usage:
les di, FPValue
lefpo

Description:LEFPO loads an extended precision floating point value into
the internal floating point operand. It also converts the
80-bit format to the internal 81-bit format used by the
floating point package.

Include:stdlib.a or fp.a


Routine: lefpol
----------------

Category: Floating point Routine

Registers on entry: CS:RET points at an extended precision (80-bit) value to
load

Registers on return: None

Flags affected: None

Example of Usage:
lefpal
dt1.345e-3

Description:LEFPOL loads an extended precision floating point value into
the internal floating point operand. It also converts the
80-bit format to the internal 81-bit format used by the
floating point package.

Unlike LEFPO, LEFPOL gets its operand directly from the code
stream. You must follow the call to lefpal with a ten-byte
(80-bit) floating point constant.
Include:stdlib.a or fp.a


Routine: itof
--------------

Category: Floating point Routine

Registers on entry: AX contains a signed integer value

Registers on return: None

Flags affected: None

Example of Usage:
movax, -1234
itof

Description:ITOF converts the 16-bit signed integer in AX to a floating
point value, storing the result in the floating point
accumuator.

Include:stdlib.a or fp.a


Routine: utof
--------------

Category: Floating point Routine

Registers on entry: AX contains an unsigned integer value

Registers on return: None

Flags affected: None

Example of Usage:
movax, -1234
itof

Description:UTOF converts the 16-bit unsigned integer in AX to a floating
point value, storing the result in the floating point
accumuator.

Include:stdlib.a or fp.a


Routine: ultof
---------------

Category: Floating point Routine

Registers on entry: DX:AX contains an unsigned 32-bit integer value

Registers on return: None

Flags affected: None

Example of Usage:
movdx, word ptr val32+2
movax, word ptr val32
ultof

Description:ULTOF converts the 32-bit unsigned integer in DX:AX to a
floating point value, storing the result in the floating
point accumuator.

Include:stdlib.a or fp.a


Routine: ltof
--------------

Category: Floating point Routine

Registers on entry: DX:AX contains a signed 32-bit integer value

Registers on return: None

Flags affected: None

Example of Usage:
movdx, word ptr val32+2
movax, word ptr val32
ltof

Description:LTOF converts the 32-bit signed integer in DX:AX to a
floating point value, storing the result in the floating
point accumuator.

Include:stdlib.a or fp.a


Routine: ftoi
--------------

Category: Floating point Routine

Registers on entry: None

Registers on return: AX contains 16-bit signed integer

Flags affected: Carry is set if conversion error occurs.

Example of Usage:
ftoi
puti;Print AX as integer value


Description:FTOI converts the floating point accumulator value to a
16-bit signed integer and returns the result in AX. If
the floating point number will not fit in AX, FTOI returns
with the carry flag set.

Include:stdlib.a or fp.a


Routine: ftou
--------------

Category: Floating point Routine

Registers on entry: None

Registers on return: AX contains 16-bit unsigned integer

Flags affected: Carry is set if conversion error occurs.

Example of Usage:
ftou
putu;Print AX as an unsigned value


Description:FTOU converts the floating point accumulator value to a
16-bit unsigned integer and returns the result in AX. If
the floating point number will not fit in AX, FTOU returns
with the carry flag set.

Include:stdlib.a or fp.a


Routine: ftol
--------------

Category: Floating point Routine

Registers on entry: None

Registers on return: DX:AX contains a 32-bit signed integer

Flags affected: Carry is set if conversion error occurs.

Example of Usage:
ftol
putl;Print DX:AX as integer value


Description:FTOL converts the floating point accumulator value to a
32-bit signed integer and returns the result in DX:AX. If
the floating point number will not fit in DX:AX, FTOL returns
with the carry flag set.

Include:stdlib.a or fp.a


Routine: ftoul
---------------

Category: Floating point Routine

Registers on entry: None

Registers on return: DX:AX contains a 32-bit unsigned integer

Flags affected: Carry is set if conversion error occurs.

Example of Usage:
ftoul
putul;Print DX:AX as an integer value


Description:FTOUL converts the floating point accumulator value to a
32-bit unsigned integer and returns the result in DX:AX. If
the floating point number will not fit in DX:AX, FTOUL returns
with the carry flag set.

Include:stdlib.a or fp.a


Routine: fpadd
---------------

Category: Floating point Routine

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:
fpadd

Description:FPADD adds the floating point operand to the floating point
accumulator leaving the result in the floating point
accumulator.

Include:stdlib.a or fp.a


Routine: fpsub
---------------

Category: Floating point Routine

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:
fpsub

Description:FPSUB subtracts the floating point operand from the floating
point accumulator leaving the result in the floating point
accumulator.

Include:stdlib.a or fp.a


Routine: fpcmp
---------------

Category: Floating point Routine

Registers on entry: None

Registers on return: AX contains result of comparison.

Flags affected: As appropriate for a comparison. You can use the
conditional branches to check the comparison after
calling this routine. Be sure to use the *signed*
conditional jumps (e.g., JG, JGE, etc.).

Example of Usage:
fpcmp
jgeFPACCgeFPOP

Description:FPCMP compares the floating point accumulator to the
floating point operand and sets the flags according to the
result of the comparison. It also returns a value in AX
as follows:

AXResult
-1FPACC < FPOP
0FPACC = FPOP
1FPACC > FPOP

Include:stdlib.a or fp.a


Routine: fpmul
--------------

Category: Floating point Routine

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:
fpmul

Description:FPMUL multiplies the floating point accumulator by the floating
point operand and leaves the result in the floating point
accumulator.

Include:stdlib.a or fp.a


Routine: fpdiv
---------------

Category: Floating point Routine

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:
fpdiv

Description:FPDIV divides the floating point accumulator by the floating
point operand and leaves the result in the floating point
accumulator.

Include:stdlib.a or fp.a


Routine: ftoa (2,m)
--------------------

Category: Floating point Routine

Registers on entry: ES:DI points at buffer to hold result (ftoa/ftoa2 only)
AL- Field width for floating point value.
AH- Number of positions to the right of the dec pt.

Registers on return: ES:DI points at beginning of string (ftoa/ftoam only)
ES:DI points at zero terminating byte (ftoa2 only)

Flags affected: Carry is set if malloc error (ftoam only)

Example of Usage:
movdi, seg buffer
moves, di
leadi, buffer
movah, 2;Two digits after "."
moval, 10;Use a total of ten positions
ftoa



Description:FTOA (2,M) converts the value in the floating point accumulator
to a string of characters which represent that value. These
routines use a decimal representation. The value in AH is
the number of digits to put after the decimal point, AL
contains the total field width (including room for the sign
and decimal point). The field width specification works
just like Pascal or FORTRAN. If the number will not fit in
the specified field width, FTOA outputs a bunch of "#"
characters.

FTOA stores the converted string at the address specified by
ES:DI upon entry. There must be at least AL+1 bytes at this
address. It returns with ES:DI pointing at the start of this
buffer.

FTOA2 works just like FTOA except it does not preserve DI.
It returns with DI pointing at the zero terminating byte.

FTOAM allocates storage for the string on the heap and returns
a pointer to the converted string in ES:DI.

Note: this routine preserves the value in the floating point
accumulator but it wipes out the value in the floating point
operand.

Include:stdlib.a or fp.a


Routine: etoa (2,m)
--------------------

Category: Floating point Routine

Registers on entry: ES:DI points at buffer to hold result (etoa/etoa2 only)
AL- Field width for floating point value.

Registers on return: ES:DI points at beginning of string (etoa/etoam only)
ES:DI points at zero terminating byte (etoa2 only)

Flags affected: Carry is set if malloc error (etoam only)

Example of Usage:
moval, 14;Use a total of 14 positions
etoam
puts
putcr
free



Description:ETOA (2,M) converts the value in the floating point accumulator
to a string of characters which represent that value. These
routines use an exponential (scientific notation)
representation. AL contains the field width. It contains
the number of print position to use when outputting the
number. The field width specification works just like Pascal
or FORTRAN. If the number will not fit in the specified
field width, ETOA outputs a bunch of "#" characters.

ETOA stores the converted string at the address specified by
ES:DI upon entry. There must be at least AL+1 bytes at this
address. It returns with ES:DI pointing at the start of this
buffer.

ETOA2 works just like ETOA except it does not preserve DI.
It returns with DI pointing at the zero terminating byte.

ETOAM allocates storage for the string on the heap and returns
a pointer to the converted string in ES:DI.

Note: this routine preserves the value in the floating point
accumulator but it wipes out the value in the floating point
operand.

Include:stdlib.a or fp.a


Routine: atof
--------------

Category: Floating point Routine

Registers on entry: ES:DI points at a string containing the representation
of a floating point number in ASCII form.

Registers on return: None

Flags affected: None

Example of Usage:
lesdi, FPStr
atof


Description: ATOF converts the string pointed at by ES:DI into a floating
point value and leaves this value in the floating point
accumulator. Legal floating point values are described
by the following regular expression:


{" "}* {+ | -} ( ([0-9]+ {"." [0-9]*}) | ("." [0-9]+)}
{(e | E) {+ | -} [0-9] {[0-9]*}}

"{}" denote optional items.
"|" denotes OR.
"()" groups items together.



Include:stdlib.a or fp.a



******************************************************************************

File I/O Routines

Featuring:
- Opening and closing files
- Creating new files
- Deleting files
- Renaming files
- File "seeking"
- Blocked I/O:
- Reading from files using getc
- Writing to files using putc and puts
- File flushing

******************************************************************************

Written by:

Mark Radleigh
&

Brian Harvey

******************************************************************************


fcreate
*Creates a new file.
*If a file already exists with the requested name, it will be deleted
and a new one will take its place.
Inputs: ES:DI- Contains address of the filename for the new file
Outputs: AX- If no error occured in creating the file, it contains a
filehandle number assigned to this file by DOS.
If an error has occurred, it contains one of the following error
codes:
3 - Path not found
4 - Too many open files
5 - Access denied
Carry flag- 0 if no error occured, 1 if error
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine creates a new file on the specified pathname. If no pathname or
device is specified, the file will be created in the current working directory.
If the file has been successfully created (No errors occured!), then this
routine returns in the ax register a number that is the DOS filehandle for
this file. Don't lose this value. You will need it when to want to close the
file (using fclose). Save the ax register in a variable after the routine call
and move the variable back into the ax register before you call the fclose
stdlib routine. See documentation for fclose for more information.

FILEHANDLE NOTICE: The filehandle returned in the ax register is not the true
DOS filehandle for this file. However, this filehandle is too be used when
calling the file routines in stdlib. In order to get the true filehandle for a
certain file, see the documentation for the stdlib routine, DOSHandle

Example:

print
db "What do you desire to create?",0
gets ;Get filename and store in es:di
fcreate ;Call routine to create file
jc error ;If the carry flag is set,
;an error has occured.
mov fileptr, ax ;Save the filehandle stored in
;the ax register for future
;use

fopen
*Opens a file for reading or writing.
*File I/O depends on value in the al register.
Inputs: ES:DI- Contains address of the filename for the file to be opened
AL- Contains 0 if the file is to be opened for reading.
Contains 1 if the file is to be opened for writing.
Outputs: AX- If no error occured in opening the file, it contains a
filehandle number assigned to this file by DOS.
If an error has occured, it contains one of the following error
codes:
2 - File not found
4 - Too many open files
5 - Access denied
12 - Invalid access
Carry flag- 0 if no error occured, 1 if error
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine opens a file for reading or writing using the specified filename
and directory (any standard DOS file pathway) in ES:DI. Using the stdlib gets
routine is an excellent and advisable way (Not to mention an easy way!) of
getting the filename in ES:DI. The user must also move one of two values into
the al register before calling fopen. To open a file for reading, the al
register must contain the value 0 and to open a file for writing, the al
register must contain the value 1. If the file has been successfully opened, a
filehandle for this file assigned by DOS. Save this filehandle in some sort of
variable so you can move it back into the ax register when you call the stdlib
routine fclose to close the file. See documentation for fclose for more
information. Examine the examples below for a suggested way of saving the
filehandle (the example uses a variable called fileptr, but the name is
arbritary).

FILEHANDLE NOTICE: The filehandle returned in the ax register is not the true
DOS filehandle for this file. However, this filehandle is too be used when
calling the file routines in stdlib. In order to get the true filehandle for a
certain file, see the documentation for the stdlib routine, DOSHandle

NOTICE FOR MULTIPLE OPEN FILES: fopen, along with fcreate and fclose, allows the
user have up to 10 files open at the same time.
In order to keep track of all the filehandles of
these open files, it is suggested that a
separate variable for the filehandle of each
of the open files be used to keep track of the
handles.

Example for opening mulitple files (same theory applies with fcreate):
print
db "What do you desire to open?",0
gets ;Get filename and store in es:di
mov al, 1 ;1 so the file will be opened
;for writing
fopen ;Call routine to open file
jc error ;If the carry flag is set,
;an error has occured, so quit!
mov fileptr, ax ;Save the filehandle stored in
;the ax register for future
;use
print
db"What is the 2nd file you wish to open?",0
gets
moval, 1
fopen;Open 2nd file for writing
jcerror;Error??
movfileptr2,ax;Save the filehandle for the 2nd
;open file in a separate
;variable


Warning: If the file the user wishes to open already exists and the user wants
to open it for writing, then the data written to the file will
overwrite the pre-exeisting data. See docs for fseek to overcome
this problem.

Example:

;Open a file for writing
print
db "What do you desire to open?",0
gets ;Get filename and store in es:di
moval, 1;1 so the file will be opened
;for writing


fopen ;Call routine to open file
jc error ;If the carry flag is set,
;an error has occured, so quit!
mov fileptr, ax ;Save the filehandle stored in
;the ax register for future
;use

;Open a file for reading
print
db "What do you desire to open?",0
gets ;Get filename and store in es:di
mov al, 0 ;0 so the file will be opened
;for reading
fopen ;Call routine to open file
jc error ;If the carry flag is set,
;an error has occured, so quit!
mov fileptr, ax ;Save the filehandle stored in
;the ax register for future
;use

fclose
*Closes an open file
*Filehandle for file to be closed needs to be in the ax register
Input: AX- Contains the filehandle variable of the file to close.
Outputs: AX- If carry flag is set (error occured), then ax contains an error
code.
If an error has occured, it contains the following error code:
6 - Invalid file handle
10 - Trouble with FREE (memory freeing routine)
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine closes an open file. Once the file is closed no I/O processes
can be made on the file. Before calling the routine, fclose, the user must
move into the ax register the filehandle assigned to this file when the file
was opened or created. The only error that can occur is if the user moved into
the ax register a filehandle that does not belong to one of the opened files.
The following example demonstrates how to close a file that was opened in one of
the fopen examples or the file that was created in the fcreate example, whose
filehandle was saved in variable called fileptr.
Example:
mov ax, fileptr;Move the DOS filehandle into
;the ax register before
;calling routine
fclose;Close the file
cmp ax, 6;If the filehandle was an
;invalid filehandle jump to
;user's code for error's
je error
;The following code is a continuation in the case that multiple files are
;open. The code close the second open file.
movax, fileptr2
fclose
cmpax, 6
jeerror

fwriteon
*Turns on the write to file mode.
*Redirects the ouput of stdlib routines putc and puts to a open file
Input: AX- Contains the filehandle of which open file to write data to.
Outputs: AX- If an error occurs in attempting to write to a file, ax will
contain one of the following error codes:
5 - Accessed denied
6 - Invalid handle
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine turns the write to disk mode on. In other words, it redirects the
output of the stdlib putc routine so that instead of writing data to the screen,
the data is written to the file whose filehandle is in the ax register when
fwriteon is called. The routine that replaces the output device of putc's ouput
actually uses what is known as Blocked I/O. Instead of writing one character
to the file each time the user calls getc, each character is stored in a buffer
in memory. When the buffer contains 256 characters, that buffer is written to
the file as a block. The buffer is then cleared and more characters can be read
with getc. Using blocked I/O is a lot faster than one character at a time. Along
with getc, the stdlib routine gets' ouput is also redirected during fwriteon
mode, since in the stdlib, gets actually just calls getc many times.

Example:
;This code would appear in a program after a file has been created or opened
;for "gets"
movax, fileptr;Move into ax filehandle of
;file to write to
fwriteon ;Call function to redirect
;the output of putc and puts
puts
fwriteoff;Turn off write to disk mode
puts
;The puts must appear after the fwriteoff command because gets automatically
;writes whatever is in ES:DI to the screen (or in this case the file). The puts
;appearing after the writeoff, prints whatever is at ES:DI to the screen. If
;the puts were to appear in the writeoon mode, the string at ES:DI would be
;written to the file twice

Example:
;This code would appear in a program after a file has been created or opened
;for "getc"
movax, fileptr;Move into ax filehandle of
;file to write to
fwriteon ;Call function to redirect
;the output of putc and puts
getc
putc
fwriteoff
;Unlike in the previous example, getc and putc may both appear in the writeon
;mode. The getc will get a character from the keyboard and store it in the al
;register. Putc will then write whatever is in the al register to the
;specified open file. In order for the user to see what character they typed
;in, in the previous example, a putc should appear after the fwriteoff call.
;Since fwriteoff redirects the putc ouput back to normal (See docs for fwriteoff
;for more info) the character in al will be put on the screen.

fwriteoff
*Turns off the write to file mode
*Redirects the output of putc back to normal (the screen!)
mode.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routines changes or redirects the ouput of stdlib's putc back to normal.
In other words, since the routine fwriteon made the ouput go to a disk file,
changing it back to normal means that after this routine is called, all putc's
used will print whatever is in the al register to the screen.

Example:
;This example gets a character from the keyboard, prints to a disk file and then
;prints to the screen the character in the al register that was entered.
movax, fileptr;Move into ax filehandle of
;file to write to
fwriteon ;Call function to redirect
;the output of putc and puts
getc;Get character and store in al
putc;Print character in al to file
fwriteoff;Change ouput of putc back to
;normal
putc;Prints character in al to
;screen
fflush
*Flushes the buffer in an opened write file to that file
Inputs:AX- Contains Stdlib filehandle of file whose buffer is to be flushed
Outputs: None.
Include:Stdlib.a or files.a
Updated: 6/14/91 First public release

This routine takes all data from the buffer associated with the Stdlib
filehandle passed in AX and writes it to the file. It then clears the buffer.
NOTE: This routine is automatically called on by Fclose.

freadon
*Turns on the read from file mode
*Changes the source of the input for the stdlib function getc
Input:AX- Contains the filehandle of which open file to read data from.
Output: AX- If an error occurs in attempting to read from a file, ax will
contain one of the following error codes:
5 - Access denied
6 - Invalid handle
8 - EOF
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine turns the read from file mode on. It redirects the source from
which stdlib's getc routine gets its "character" from. Instead of getting the
character from the keyboard, the redirected getc reads a character from a opened
file. Actually, this routine uses the blocked I/O idea discussed in the writeon
documentation. This routine when called for the first time, meaning the buffer
for the current file to be read from is clear, will read it 256 characters from
(If there is that many) a file and store it in the buffer. The first character
in the buffer is then put in the al register for the user to then use for
whatever they wish. The next time the user calls getc (without calling the
freadoff rotuine yet) the next character in the buffer will be stored in the al
register. When the buffer is empty, another 256 bytes will be read into it. When
the routine freadoff is called, any getc routines called after that will get
a character from the keyboard.

Example:
movax, fileptr;Move the filehandle of the
;file to read from into ax
freadon;Turn on read mode!
movcx, 10;Set up loop to read 10
;characters from a file and
;print them to the screen
loop1:getc;Get character from buffer and
;store in al
jcerror;If error in reading from file
;jump to user's code for
;handling code
putc;Print character in al to the
;screen
looploop1
freadoff;turn read mode off from this
;file

freadoff
*Turns off the read from file mode
*Redirects the source of the data for stdlib's getc routine back to
normal

This routine changes the source from which stdlib's getc routine gets its
"character" from back to normal. After calling this routine, instead of reading
characters from the disk, using blocked I/O, the getc routine will get
it's "character" from the keyboard.

For code example of how to use freadoff, see the example of code above for
freadon.


fseek
*Moves the file pointer of a file to anywhere in the file
Inputs:SI- Contains the filehandle variable of the file to be used, or "seeked"
AL- Contains the offset from where to start the file seeking.
0 - Seek from the begining of the file.
1 - Seek from current pointer position
2 - Seek backwards from the end of file
CX:DX- Distance to move in file, in bytes.
Outputs: DX:AX- Contains the new file position if no error
AX- One of the following error codes if an error occured while
"seeking":
1 - Invalid function
6 - Invalid handle
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine allows the user the move the file pointer to any position within
a file. You can not move backwards in a file by having a negative value in
CX:DX. The value in CX:DX must be an unsigned integer.

Example:
movsi, fileptr;Move the filehandle of the
;file to be seeked
moval, 0;Start moving pointer from
;beginning of file
xorcx, cx;Clear the cx register
movdx, 10;Move file pointer 10 bytes
;into file
fseek;Seek!!!
jcerror;Jump to error code if error

To find out where the file pointer currently is in the file, first xor cx and
dx registers and call fseek. It will return in DX:AX the file pointer's
position.
movsi, fileptr;Move the filehandle of the
;file to be seeked
moval, 1;Start moving pointer from
;the current position
xorcx, cx;Clear the cx register
xordx, dx;Clear the dx register
fseek;Seek!!!
jcerror;Jump to error code if error
;else DX:AX contains the current
;File pointer position.


DOSHandle
*Returns in the ax register the true DOS filehandle for a file
Input:AX- Contains the filehandle for the file given to the user from
stdlib routine, fopen or fcreate
Ouputs:AX- Contains the true filehandle given to the requested file by DOS
AX- If an error occured, it contains the following error code:
1 - Invalid pseudo-filehandle
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine returns in the ax register the true filehandle variable given by
DOS for a particular file. The filehandle returned when calling the stdlib
functions, fcreate and fopen, is not the true filehandle for the file used
in those routines. The value returned is a value created by the routines, which
stores the filehandles for multiple files in a structure in memory. The value
returned from those functions is actually the index into the structure to the
real filehandle for the file. This function, DOSHandle, returns from this
structure in memory the actual filehandle for a file that has been opened.
NOTICE: This routine is only useful to those who need to know the real
filehandle of a file that has been created or opened with fopen or fcreate. For
those who will only be using the File I/O routines provided in stdlib then
this routine will be of no importance. It is provided only for advanced assembly
language programmers who with to do other things with files and need to know
their real filehandle values.

Example:
movax, fileptr;Move into ax the filehandle
;given to the user file fopen
;or fcreate
DOSHandle;Get the true filehandle for
;a file and store it in the
;ax register
movtruehandle, ax

frename
*Renames a file
Input:DX:SI- Contains the original pathname of the file
ES:DI- Contains the new pathname of the file
Ouputs:AX- Contains one of the following error codes if an error occured:
2 - File not found
5 - Access denied
17 - Not the same device
Carry flag- 0 if no error occured, 1 if error.
Include:Stdlib.a or files.a
Updated:6/14/91First public release

This routine renames the file whose name appears in a string at DX:SI with the
name that appears at the string pointed at by ES:DI. If an error occurs, then
an appropriate error code appears in the ax register.

Example:
print
db"Enter the source filename: ",0
gets
movdx, es
movsi, di
print
dbcr, lf, "Enter the new filename: ",0
gets
frename
jcerror

fdel
*Deletes a file
Input: ES:DI- Contains the address of zero terminated pathname of file
Output: AX- Contains one of the following error codes if an error occured:
2 - File not found
5 - Access denied
Carry flag- 0 if no error occured, 1 if error.
Include: Stdlib.a or files.a
Updated: 6/14/91 First public release

This routine deletes the filename that is in the string that ES:DI points to.

Example:
print
db"Name of file to delete?",0
gets
fdel;Delete the file!
jcerror;Jump to error code if an error




======================
Miscellaneous Routines
======================

This routines either defy categorization, or they haven't been properly
organized yet.

Mostly (like the rest of this library) they have simply been stuck here
until somebody gets the time to reorganize *everything*.




Routine: Random
----------------

Author: Unknown. Copied off a file on one of the networks,
tweaked, and added to the library. Any info on the
original author would be appreciated.

Category: Miscellaneous

Registers on entry: None

Registers on return: AX-Contains random number

Flags affected: None

Example of Usage:
random;Generate random number in AX
puti;Print the random number.


Description:

This routine computes a 16-bit random number each time you call it. It
returns the random number in the AX register. You may treat this as a signed
or unsigned value as it utilizes all 16 bits. This code uses an internal
table of seed values. If you are interested in producing repeatable sequences
of random numbers, please look at the source listings for this file.

If you are interested in producing truly random values (well, closer than you
will get from this code by calling it right off the bat) look at the randomize
routine which tweaks the seed table based on the current time of day clock
value.

Include:stdlib.a or misc.a


Routine: Randomize
-------------------

Author: Unknown. Copied off a file on one of the networks,
tweaked, and added to the library. Any info on the
original author would be appreciated.

Category: Miscellaneous

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:
randomize;Randomize the seeds.
random;Get a brand new random number
puti;Print it

Description:

Random's internal seed table is hard coded. It was designed to produce a
sequence of random numbers with a very long period. However, each time you
run a program using Random, it will generate the exact same sequence of
random numbers. This could be distressing, for example, in a game where
after a while the player(s) could memorize some sequence of events based
on the random number generator.

Randomize uses the time of day clock value to scramble the internal random
seed table. If you call randomize before using random the first time, you
will generally get a different sequence of random numbers each time you
run the program.

Note that it is dangerous to call randomize more than once inside any program.
The time of day clock is not a random source when invoked fairly often.
Furthermore, once the seeds are randomized, random does a pretty good job of
randomizing the results.

Include:stdlib.a or misc.a


Routine: cpuid
---------------

Author: Original implementation was supplied by Intel Corp.
Various modifications were made for inclusion into
the UCR Standard Library.

Category: Miscellaneous

Registers on entry: None

Registers on return: AX-Contains processor ID (86, 286, 386, or
486. Note 8088=86).

BX-Contains coprocessor ID (87, 286, 387,
or 487). Note that a true 486 will have
an 80487 built-in, 486sx chips, however, will
not.

Flags affected: None

Example of Usage:
cpuid
cmpax, 8086;Is this an 8086?

Description:

For those programs which absolutely need to know the CPU in use, CPUID does
a reasonable job (in DOS real mode) of figuring this out for you. As with
all CPU identification routines, there are bound to be some problems with this
one when operating in protected mode. But for normal DOS applications it
appears to work great. This routine came straight from the horse's mouth
(Intel Corporation) so you can place a little more faith in it than most that
are floating around. Intel's blessing doesn't guarantee that this routine
is perfect, though; always keep that in mind.

Include:stdlib.a or misc.a


===================
SmartArray Routines
===================

The SmartArray routines provide a consistent and easy to master interface to
vectors, matrices, and higher-dimension arrays. It is a weak attempt at an
abstract, encapsulated, array data type (weak because the internal structure
is still visible, indeed, intended to be visible, to the main program). These
routines include many operations stolen from the APL programming language. As
such, they comprise a powerful set of matrix operations. On the other hand,
because of their generality, they do not perform as quickly as hand-optimized
code doing the same thing. These routines definitely represent a trade-off
between ease of use and performance. That is not to say that these routines
are all slow. Some operations, like matrix multiplication, are so slow that
the overhead of dealing with arrays in this fashion pales in comparison.
For other operations (e.g., extracting an element of an array), the overhead
required may far exceed the actual work performed. This is why these routines
do provide access to the internal data structures.

The array access routines come in two basic groups: general array access and
array operations. The general array access routines let you allocate arrays,
access arrays, initialize arrays, and copy arrays. The array operation
routines let you perform high-level operations on the arrays.

SmartArrays are described by a descriptor (also called a "dope vector"). This
descriptor uses the following data structure:

DopeVectorstruc
ArrayDatadd?
SizeInBytesdw?
ElementSizedw?
NumDimensionsdw?
DimensionListdw?;One word for each dimension
DopeVectorends

The first double word is a pointer to the actual array data. This is typically
(though not necessarily) allocated somewhere on the heap with malloc. The
SmartArrays package stores all multi-dimensional arrays in row major order.


The second field above, SizeInBytes, gives the total size of the array data.
The SmartArray routines use this field for block copies and other operations
where it's nice to know the actual size of the array, in bytes. Although
SmartArrays are typically allocated on the heap, there is no guarantee of this.
In particular, the SmartArray routines make no assumptions about free bytes
immediately following the array's data. The SmartArray routines only
manipulate the specified number of bytes when treating the array as a whole.

The ElementSize field gives the number of bytes per array element. Any value
may go here, but the SmartArrays package handles 1, 2, 4, 8, and 10 byte
elements best (especially 1, 2, and 4 byte element sizes). Since most arrays
use one of these sizes, you're in great shape.

The NumDimensions field is an small integer which gives the number of dimen-
sions in this array.

The DimensionList is an array (despite its declaration) containing the number
of elements specified in the NumDimensions field. Each entry is a word giving
the number of array elements in that dimension.



The SmartArrays package current defines the following error codes (which also
appear as equates in the stdlib.a files):

AryNoError=0;Should never occur
AryTypeMismatch=1;Array type mismatch
AryOverflow=2;Arithmetic overflow
AryDiv0=3;Division by zero
AryIllegalOp=4;Illegal operation on array
AryBounds=5;Array index error
AryMemory=6;Memory allocation error
AryBadDV=7;Illegal dope vector
AryNull=8;Null pointer to array data


If an error occurs, the SmartArray routines return with the carry set and
the error code in AX. If no error occurs, then the SmartArray routines return
with the carry flag clear. This is assuming that you have *not* defined the
"AryErrorAbort" symbol before the "include stdlib.a" statement in your program.
If you define the "AryErrorAbort" symbol before the include, the calls to the
SmartArray routines emit some additional code which checks for any errors. If
an error occurs in this case, the system will print an appropriate error
message and abort the program.

In addition to the array dope vector structure, the stdlib.a files
also contain a macro for declaring SmartArrays within your program. Although
it is perfectly possible to allocate dope vectors on the heap (and, indeed,
this is a common occurrence), more often than not it is possible to allocate
the dope vectors, and even the array data, in your data segment. The
SmartArrays package provides a macro, "array", to specifically aid in this
task. The array macro takes the following parameters:

arrayname, element_size, dimension_list, opt_initial_values

The name is the label you wish to attach to this smart array data structure.
This must be a valid assembly language symbol. Note that the symbol must
*not* appear in the normal label field. The macro does the processing of this
label and it must appear as a parameter to the macro.


The element_size parameter must be an integer value which is the number of
bytes to allocate for each array element.

The dimension_list parameter is a list of numbers, separated by commas and
surrounded by "<" and ">" which list the number of elements in each array
dimension. This list must not be empty and none of the dimension values should
be zero.

The optional initial values is another list of values surrounded by "<" and
">". This parameter is optional and need not be present. If absent, the
array macro generates a dope vector *only*. It initializes the array data
pointer field to NULL. If there are values present in the initial values
list, the array macro will allocate storage for the array immediately following
the dope vector and initializes the array elements to the value(s) in the
initial value list. If there are too many items in the initial values list,
the array macro ignores the extra values. If there are too few items, the
array macro reuses the values from the beginning of the list (over and over
again, if necessary).

Some examples (no initial values):


a1:array [0..1,0..1] of integer2;

arraya1, 2, <2,2>


a2:array [0..7] of unsigned4;

arraya2, 4, <8>

a3:array [0..3,0..3,0..3] of real8;

arraya3, 8, <4,4,4>


Some examples with initial values:

arrayb1, 2, <4>, <1,2,3,4>

arrayb2, 2, <3>, <1,2,3,4>;ignores "4"

arrayb3, 2, <4>, <1,2,3>;Generates 1,2,3,1

arrayb4, 2, <4,4>, <1,0,0,0,0>

The last example generates the following identity matrix:

1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

The array macro reuses initial values once it exhausts the list. It also fills
the array in row-major order (that is, it fills up the array a row at a time).
Since each row in b4 is four bytes long and the initial values list contains
five bytes, the first pass through the initial values list creates the follow-
ing:

1 0 0 0
0 x x x
x x x x
x x x x

Since the initialization is not complete, the second pass through the initial
values list generates:

1 0 0 0
0 1 0 0
0 0 x x
x x x x

and so on. It is important to note that the array macro ignores row/column
boundaries while initializing the array. Array simply treats each array as
a one-dimensional object during initialization.

The array routines themselves come in three basic forms: general array manip-
ulation routines which operate on arrays of any size or dimension, vector
operations which operate only on single dimension arrays, and matrix operations
which operate on two-dimensional arrays. General array operations typically
begin with the letters "Ary", vector operations usually begin with "vect", and
matrix routines usually begin with the letters "Mat". All of these routines,
despite their name, belong to the SmartArrays package.



Interrupt-Driven Serial Port I/O Package
========================================

One major problem the the PC's BIOS is the lack of good interrupt driven
I/O support for the serial port. The BIOS provides a mediocre set of polled
I/O facilities, but completely drops the ball on interrupt driven I/O.

This set of routines in the standard library provides polled I/O support
to read and set the registers on the 8250 (or other comparable chip, e.g.,
16450) as well as read and write data (polled). In addition, there are
a pair of routines to initialize and disable the interrupt system as well
as perform I/O using interrupts.

Typical polled I/O session:

1. Initialize chip using polled I/O routines.
2. Read and write data using ComRead and ComWrite routines.

Typical interrupt driven I/O session:

1. Initialize chip using polled I/O routines.
2. Read and write data using ComIn and ComOut routines.

Of course, all the details of serial communications cannot be discussed
here- it's far too broad a subject. These routines, like most in the
library, assume you know what you're doing. They just make it a little
easier on you. If you don't understand anything about serial communications,
you *might* be able to use these routines, but they were not written with
that audience in mind. There are several good references on serial communi-
cations; "C Programmer's Guide to Serial Communications" comes to mind. If
you've never looked at the 8250 or comparable chips before, you might want
to take a look at a reference such as this one if the routines in this
section don't make much sense.

Note: This routines are set up to use the COM1: hardware port. See the
source listings if you want to access a different serial port. Perhaps in
a future release we will modify this code to work with any serial port.


Routine: ComBaud
-----------------

Author: Randall Hyde

Category:Serial Communications

Registers on entry: AX-BPS (baud rate): 110, 150, 300, 600, 1200,
2400, 4800, 9600, 19200

Registers on return: None

Flags affected: None

Example of Usage:
movax, 9600;Set system to 9600 bps
ComBaud
Description:

ComBaud programs the serial chip to change its "baud rate" (technically,
it's "bits per second" not baud rate). You load AX with the appropriate
bps value and call ComBaud, as above. Note: if AX is not one of the legal
values, ComBaud defaults to 19.2kbps.

Include:ser.a or stdlib.a

Routine: ComStop
-----------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AX-# of stop bits (1 or 2)

Registers on return: None

Flags affected: None

Example of Usage:
movax, 2;Set system to send 2 stop bits
ComStop
Description:

ComStop programs the serial chip to transmit the specifed number of stop
bits when sending data. You load AX with the appropriate value and call
ComStop, as above. Note that this only affects the output data stream. The
serial chip on the PC will always work with one incoming stop bit, regardless
of the setting. Since additional stop bits slow down your data transmission
(by about 10%) and most devices work fine with one stop bit, you should
normally program the chip with one stop bit unless you encounter some
difficulties. The setting of this value depends mostly on the system you
are connecting to.

Include:ser.a or stdlib.a

Routine: ComSize
-----------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AX-# of data bits to transmit (5, 6, 7, or 8)

Registers on return: None

Flags affected: None

Example of Usage:
movax, 8;Set system to send 8 data bits
ComSize
Description:

ComSize programs the serial chip to transmit the specifed number of data
bits when sending data. You load AX with the appropriate value and call
ComSize, as above. The setting of this value depends mostly on the system
you are connecting to.

Include:ser.a or stdlib.a

Routine: ComParity
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AX- Bits 0, 1, and 2 are defined as follows:
bit 0- 1 to enable parity, 0 to disable.
bit 1- 0 for odd parity, 1 for even.
bit 2- Stuck parity bit. If 1 and bit 0 is 1, then the parity bit
is always set to the inverse of bit 1.

Registers on return: None

Flags affected: None

Example of Usage:
movax, 0;Set NO parity
ComParity
.
.
.
movax, 11b;Set even parity
ComParity
Description:

ComParity programs the serial chip to use various forms of parity error
checking. If bit zero of AX is zero, then this routine disables parity
checking and transmission. In this case, ComParity ignores the other
two bits (actually, the 8250 ignores them, ComParity just passes them
through). If bit zero is a one, and bit two is a zero, then bit #1
defines even/odd parity during transmission and receiving. If bit #0
is a one and bit two is a one, then the 8250 will always transmit bit #1
as the parity bit (forced on or off).

Include:ser.a or stdlib.a

Routine: ComRead
-----------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL-Character read from port

Flags affected: None

Example of Usage:
ComRead
movBuffer, al

Description:

ComRead polls the port to see if a character is available in the on-chip
data register. If not, it waits until a character is available. Once
a character is available, ComRead reads it and returns this character in
the AL register.

Warning: do *not* use this routine while operating in the interrupt mode.
This routine is for polled I/O only.

Include:ser.a or stdlib.a

Routine: ComWrite
------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AL-Character to write to port

Registers on return: None

Flags affected: None

Example of Usage:
moval, 'a'
ComWrite

Description:

ComWrite polls the port to see if the transmitter is busy. If so, it waits
until the current transmission is through. Once the 8250 is done with the
current character, ComWrite will put the character in AL into the 8250
transmit register.

Warning: do *not* use this routine while operating in the interrupt mode.
This routine is for polled I/O only.

Include:ser.a or stdlib.a

Routine: ComTstIn
------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL=0 if no char available, 1 if char available

Flags affected: None

Example of Usage:

Wait4Data:ComTstIn
cmpal, 0
jeWait4Data

Description:

ComTstIn polls the port to see if any input data is available. If so,
it returns a one in AL, else it returns a zero.

Warning: do *not* use this routine while operating in the interrupt mode.
This routine is for polled I/O only.

Include:ser.a or stdlib.a

Routine: ComTstOut
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = 1 if xmitr available, 0 if not

Flags affected: None

Example of Usage:

WriteData:
ComTstOut
cmpal, 0
jeWriteData
moval, 'a'
ComWrite

Description:

ComTstIn polls the port to see if the transmitter is currently busy. If so,
it returns a zero in AL, else it returns a one.

Warning: do *not* use this routine while operating in the interrupt mode.
This routine is for polled I/O only.

Include:ser.a or stdlib.a

Routine: ComGetLSR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = LSR value

Flags affected: None

Example of Usage:

ComGetLSR

Description:

Reads the LSR (line status register) and returns this value in AL. The
LSR using the following layout.

Line Status Register (LSR):

bit 0-Data Ready
bit 1-Overrun error
bit 2-Parity error
bit 3-Framing error
bit 4-Break Interrupt
bit 5-Transmitter holding register is empty.
bit 6-Transmit shift register is empty.
bit 7-Always zero.

Warning: In general, it is not a good idea to call this routine while
the interrupt system is active. It won't hurt anything, but the value
you get back may not reflect properly upon the last/next character you
read.

Include:ser.a or stdlib.a

Routine: ComGetMSR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = MSR value

Flags affected: None

Example of Usage:

ComGetMSR

Description:

The MSR (modem status register) bits are defined as follows:

Modem Status Register (MSR):

bit 0-Delta CTS
bit 1-Delta DSR
bit 2-Trailing edge ring indicator
bit 3-Delta carrier detect
bit 4-Clear to send
bit 5-Data Set Ready
bit 6-Ring indicator
bit 7-Data carrier detect


Warning: In general, it is not a good idea to call this routine while
the interrupt system is active. It won't hurt anything, but the value
you get back may not reflect properly upon the last/next character you
read.

Include:ser.a or stdlib.a

Routine: ComGetMCR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = MCR value

Flags affected: None

Example of Usage:

ComGetMCR

Description:

The MCR (modem control register) bits are defined as follows:

Modem Control Register (MCR):

bit 0-Data Terminal Ready (DTR)
bit 1-Request to send (RTS)
bit 2-OUT 1
bit 3-OUT 2
bit 4-Loop back control.
bits 5-7-Always zero.


The DTR and RTS bits control the function of these lines on the 8250.
They are useful mainly for polled I/O handshake operations (though they
*could* be used with interrupt I/O, it's rarely necessary unless your
main application is *really* slow and the data is coming in real fast.

Out1 and Out2 control output pins on the 8255. Keep in mind that the OUT1
pin enables/disables the serial port interrupts. Play with this *only* if
you want to control the interrupt enable.

Loop back control is mainly useful for testing the serial port or checking
to see if a serial chip is present.

Include:ser.a or stdlib.a

Routine: ComSetMCR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AL = new MCR value

Registers on return: None

Flags affected: None

Example of Usage:

moval, NewMCRValue
ComSetMCR

Description:

This routine writes the value in AL to the modem control register. See
ComGetMCR for details on the MCR register.

Include:ser.a or stdlib.a

Routine: ComGetLCR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = LCR value

Flags affected: None

Example of Usage:

ComGetLCR

Description:

The LCR (line control register) bits are defined as follows:

Line Control Register (LCR):

bits 0,1-Word length (00=5, 01=6, 10=7, 11=8 bits).
bit 2-Stop bits (0=1, 1=2 stop bits [1-1/2 if 5 data bits]).
bit 3-Parity enabled if one.
bit 4-0 for odd parity, 1 for even parity (assuming bit 3 = 1).
bit 5-1 for stuck parity.
bit 6-1=force break.
bit 7-1=Divisor latch access bit. 0=rcv/xmit access bit.

Since the standard library provides routines to initialize the serial chip
(which is the purpose of this port) you shouldn't really mess with this
port at all. You may, however, use ComGetLCR to see what the current
settings are before making any changes.

Warning: (applies mainly to ComSetLCR) DO NOT, UNDER ANY CIRCUMSTANCES,
CHANGE THE DIVISOR LATCH ACCESS BIT WHILE OPERATING IN INTERRUPT MODE.
The interrupt service routine assumes the rcv/xmit register is mapped in
whenever an interrupt occurs. If you must play with the divisor latch,
turn off interrupts before changing it. Always set the divisor latch
access bit back to zero before turning interrupts back on.

Include:ser.a or stdlib.a

Routine: ComSetLCR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AL = new LCR value

Registers on return: None

Flags affected: None

Example of Usage:

; If this maps in the divisor latch, be sure we're not operating with
; serial interrupts!

moval, NewLCRValue
ComSetLCR

Description:

This routine writes the value in AL to the line control register. See
ComGetLCR for details on the LCR register. Especially note the warning
about the divisor latch access bit.

Include:ser.a or stdlib.a

Routine: ComGetIIR
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL = IIR value

Flags affected: None

Example of Usage:

ComGetIIR

Description:

The IIR (interrupt identification register) bits are defined as follows:

Interrupt ID Register (IIR):

bit 0-No interrupt is pending (interrupt pending if zero).
bits 1,2-Binary value denoting source of interrupt:
00-Modem status
01-Transmitter Hold Register Empty
10-Received Data Available
11-Receiver line status
bits 3-7Always zero.

This value is of little use to anyone except the interrupt service routine.
The ISR is the only code which should really access this port.

Include:ser.a or stdlib.a

Routine: ComGetIER
-------------------

Author: Randall Hyde


Category: Serial Communications

Registers on entry: None

Registers on return: AL = IER value

Flags affected: None

Example of Usage:

ComGetIER

Description:

The IER (line control register) bits are defined as follows:

Interupt enable register (IER):

If one:
bit 0-Enables received data available interrupt.
bit 1-Enables transmitter holding register empty interrupt.
bit 2-Enables receiver line status interrupt.
bit 3-Enables the modem status interrupt.
bits 4-7-Always set to zero.

Normally, the interrupt initialization procedure sets up this port. You may
read or change its value as you deem necessary to control the types of
interrupts the system generates. Note that the interrupt service routine
(ISR) in the library ignores errors. You will need to modify the ISR if you
need to trap errors.

Include:ser.a or stdlib.a

Routine: ComSetIER
-------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: AL = new IER value

Registers on return: None

Flags affected: None

Example of Usage:

moval, NewIERValue
ComSetIER

Description:

Writes the value in AL to the IER. See ComGetIER for more details.

Include:ser.a or stdlib.a

Routine: ComInitIntr
---------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:

ComInitIntr

Description:

Sets up the chip to generate interrupts and programs the PC to transfer
control to the library serial interrupt service routine when an interrupt
occurs. Note that other than interrupt initialization, this code does not
initialize the 8250 chip.

Include:ser.a or stdlib.a

Routine: ComDisIntr
--------------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: None

Flags affected: None

Example of Usage:

ComDisIntr

Description:

This routine uninstalls the ISR and programs the chip to stop the generation
of interrupts. You must call ComInitIntr after calling this routine to
turn the interrupt system back on.

Include:ser.a or stdlib.a

Routine: ComIn
---------------

Author: Randall Hyde

Category: Serial Communications

Registers on entry: None

Registers on return: AL=character read from buffer or port

Flags affected: None

Example of Usage:

ComIn


Description:

ComIn is the input routine associated with interrupt I/O. It reads the
next available character from the serial input buffer. If no characters
are avialable in the buffer, it waits until the system receives one before
returning.

Include:ser.a or stdlib.a

Routine: ComOut
----------------

Author: Randall Hyde


Category: Serial Communications

Registers on entry: AL=Character to output

Registers on return: None

Flags affected: None

Example of Usage:


ComOut

Description:

ComOut is the output routine associated with interrupt I/O. If the serial
transmitter isn't currently busy, it will immediately write the data to the
serial port. If it is busy, it will buffer the character up. In most cases
this routine returns quickly to its caller. The only time this routine
will delay is if the buffer is full can you cannot add any additional
characters to it.

Include:ser.a or stdlib.a

Linked list manipulation routines
=================================

These routines manipulate items in a linked list. Internally the system
represents the data as a doubly linked list, although your program should
not rely on the internal structure of the data structure.

There are two structures of interest defined in the LISTS.A file: LIST
and NODE. Use variables of type LIST to create brand new lists. Use
variables of type NODE to hold the entries in the list.

These structures take the following form:

Liststruc
Sizedw?;Size, in bytes, of a node in the list
Headdd0;Ptr to start of list
Taildd0;Ptr to end of list
Currentdd0;Pointer to current node
Listends

Nodestruc
Nextdd?;Ptr to next node in list
Prevdd?;Ptr to prev node in list
NodeDatadb??;Data immediately follows Prev
Nodeends


There are two ways to create a new list: statically or dynamically.
Consider static allocation first. In this case, you create a list variable
by declaring an object of type LIST in a data segment, e.g.,

MyListlist<25>

You *must* supply the size (in bytes) of a node in the list. Note that the
size should *not* include the eight bytes required for the next and prev
pointers. This allows you to change the internal structure of the list
(e.g., to a singly linked list) without having to change other code. You
can easily compute this as follows:

MyListlist<(sizeof MyNode) - (sizeof Node)>

When you declare lists in this fashion, the definition automatically
initializes the list to an empty list.

You can also create a list dynamically by calling the CreateList routine.
To CreateList you must pass the size of a Node (not including the pointers)
in the CX register. It allocates storage for the list variable on the
heap and returns a pointer to this new (empty) list in es:di.

movcx, (sizeof MyNode) - (sizeof Node)
CreateList
movword ptr MyListPtr, di
movword ptr MyListPtr+2, es


To create nodes for your list, you should "overload" the NODE definition
appearing the in LISTS.A file. This works best under MASM 6.0 and TASM 3.0,
which support object-oriented programming, though it isn't that difficult to
accomplish with other assemblers. A mechanism compatible with *all*
assemblers follows:

To create a brand new node is easy, just do the following:

MyNodestruc
db(size Node) dup (0) ;Inherit all fields from NODE.
Field1db?;User-supplied fields for this
Field2dw?; particular node type.
Field3dd?; " " " "
Field4real43.14159; " " " "
MyNodeends

Note that the NODE fields must appear *first* in the data structure.
The list manipulation routines assume that the list pointers in NODE appear
at the beginning of the structure.

The CurrentNode field of the list data structure points at a "current" node
in the list. The current node is the last node operated on in the case of
insert, append, peek, etc. In the event a node is removed, the current node
will be the next node after the node removed. In general, the current node
can be thought of as a "cursor" which wanders through the list according to
the operations occuring. Since most list operations occur on the next node
in a list, keeping the CurrentNode field updated speeds up access to the
list.

You can use the following routines to implement the corresponding data
structures (which can all be implemented using lists):

FIFO Queues:

AppendLastm, AppendLast, Remove1st, and Peek1st (technically, using Peek1st
is cheating, but so what).



Deques (double ended queues):

All the FIFO routines plus InsertFirstm, InsertFirst, RemoveLast, and
PeekLast (PeekLast is cheating too).


Lists:

All of the above plus InsertCur, InsertmCur, AppendCur, AppendmCur,
RemoveCur, Insert, Insertm, Append, Appendm, Remove, Index, RotateLeft,
RotateRight, NextNode, and PrevNode.

For those who care about such things, the UCR Standard Library implements
the list data structure using a doubly linked list. However, it is a
true generic (encapsulated) data type and your code needed be at all
concerned about the internal structure. Furthermore, assuming you treat
it like an encapsulated data structure, you can modify the internal list
structure and not break any programs which use the list data types.





Routine: CreateList
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: CX-Size of data (in bytes) to store at each node

Registers on return: ES:DI-Pointer to new list variable on heap

Flags affected: Carry set if CreateList cannot allocate sufficient
storage on the heap for the list variable.

Example of Usage:
movcx, (sizeof MyNode) - (sizeof Node)
CreateList
jcListError
movword ptr ListVarPtr, di
movword ptr ListVarPtr+2, es

Description:

CreateList allocates storage for a list variable on the head and initializes
that variable to the empty list. It also sets up the size field of the
list variable based on the value passed in the CX register. It returns
a pointer to the newly created list in the ES:DI registers.

This routine initializes the CurrentNode field to NIL. Any node inserted
before or after the current node will be inserted as the first node in this
case.

Include:lists.a or stdlib.a



Routine: AppendLast (m)
------------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: DX:SI-Pointer to node to add to list (AppendLast)
DX:SI-Pointer to block of data (sans list stuff)
to add to end of list (AppendLastm)
ES:DI-Pointer to list.

Registers on return: ES:DI-Pointer to list.

Flags affected: Carry set if AppendLastm cannot allocate sufficient
storage on the heap for the list variable.

Examples of Usage:

; Append data statically declared as ANode to the end of the list pointed at
; by the list variable "ListVar".

ldxiANode
lesdi, ListVar
AppendLast

; Create a node from the data at address "MyData". Build the node on the
; heap and append this node to the end of the list pointed at by ListVar.

ldxiMyData
lesdi, ListVar
AppendLastm
jcBadListError

Description:

AppendLast and AppendLastm add a node to the end of a list. AppendLast works
with whole nodes. It is useful, for example when moving a node from one
list to another or when dealing with nodes that were created statically in
the program. It requires nodes properly declared using the NODE data type
in the LIST.A include file.

AppendLastm builds a new node on the heap and appends this node to the end
of the specified list. The difference between AppendLastm and AppendLast is
that AppendLastm does not require a predefined node. Instead, DX:SI points
at the data for the node (the number of bytes is specified by the ListSize
field of the LIST data type). AppendLastm allocates memory, copies the data
from DX:SI to the data field of the new node, and then links in the new node
to the specified list.

The new node added to the list becomes the CurrentNode.

Include:stdlib.a or lists.a



Routine: Remove1st
-------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list variable.


Registers on return:DX:SI-Pointer to node removed from the front of
the list (NIL if nothing in list).

Flags affected: Carry set if the list was empty.

Examples of Usage:

; The following loop removes all the items from a list and processes each
; item.

DoAllOfList:lesdi, MyList
Remove1st
jcDidItAll

jmpDoAllOfList
DidItAll:


Description:

Remove1st removes the first item from a list and returns a pointer to that
item in DX:SI. If the list was empty, then it returns a NIL pointer in
DX:SI and returns with the carry flag set.

Note that you can use the AppendLast(m) and Remove1st routines to implement
and manipulate a FIFO queue data structure. Peek1st is another useful
routine which returns the first item on a list without removing it from
the list.

The second node in the list (the one after the node just removed) becomes
the new CurrentNode. If there are no additional nodes in the list, the
CurrentNode variable gets set to NIL.

Include:stdlib.a or lists.a




Routine: Peek1st
-----------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list variable.

Registers on return:DX:SI-Pointer to node at the beginning of
the list (NIL if nothing in list).

Flags affected: Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
Peek1st
jcNothingThere

Description:

Peek1st is similar to Remove1st in that it returns a pointer to the first
item in a list (NIL if the list is empty). However, it does not remove the
item from the list. This is useful for performing a "non-destructive" read
of the first item in a FIFO queue.

This routine sets the CurrentNode field to the first node in the list.

Include:stdlib.a or lists.a



Routine: Insert1st (m)
-----------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: DX:SI-Pointer to node to add to list (Insert1st)
DX:SI-Pointer to block of data (sans list stuff)
to add to end of list (Insert1stm)
ES:DI-Pointer to list.

Registers on return: ES:DI-Pointer to list.

Flags affected: Carry set if Insertm cannot allocate sufficient
storage on the heap for the list variable.

Examples of Usage:

; Insert data statically declared as ANode to the beginning of the list
; pointed at by the list variable "ListVar".

ldxiANode
lesdi, ListVar
Insert1st

; Create a node from the data at address "MyData". Build the node on the
; heap and insert this node to the beginning of the list pointed at by
; ListVar.

ldxiMyData
lesdi, ListVar
Insert1stm
jcBadListError

Description:

Insert1st and Insert1stm add a node to the beginning of a list. Insert1st
works with whole nodes. It is useful, for example when moving a node from one
list to another or when dealing with nodes that were created statically in
the program. It requires nodes properly declared using the NODE data type
in the LISTS.A include file.

Insert1stm builds a new node on the heap and inserts this node to the start
of the specified list. The difference between Insert1stm and Insert1st is
that Insert1stm does not require a predefined node. Instead, DX:SI points
at the data for the node (the number of bytes is specified by the ListSize
field of the LIST data type). Insert1stm allocates memory, copies the data
from DX:SI to the data field of the new node, and then links in the new node
to the specified list.

Note that Insert1st/Insert1stm can be used to create Deque data structures.

The newly inserted node becomes the CurrentNode in the list.

Include:stdlib.a or lists.a



Routine: RemoveLast
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list variable.

Registers on return:DX:SI-Pointer to node removed from the end of
the list (NIL if nothing in list).

Flags affected: Carry set if the list was empty.

Examples of Usage:

; The following loop removes all the items from a list and processes each
; item.

DoAllOfList:lesdi, MyList
RemoveLast
jcDidItAll

jmpDoAllOfList
DidItAll:


Description:

RemoveLast removes the last item from a list and returns a pointer to that
item in DX:SI. If the list was empty, then it returns a NIL pointer in
DX:SI and returns with the carry flag set.

Note that you can use the Insert1st(m) and RemoveLast routines to implement
and manipulate a DEQUE queue data structure (along with the FIFO routines:
AppendLast(m), Rmv1st, and Peek1st). PeekLast is another useful
routine which returns the last item on a list without removing it from
the list.

The last node in the list (the one before the node just removed) becomes the
new CurrentNode in the list. If the list is empty, CurrentNode gets set to
NIL.

Include:stdlib.a or lists.a




Routine: PeekLast
------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list variable.

Registers on return:DX:SI-Pointer to node at the end of
the list (NIL if nothing in list).

Flags affected: Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
PeekLast
jcNothingThere

Description:

PeekLast is just like Peek1st except it looks at the last node on the list
rather than the first. It does the same job as RemoveLast except it does
not remove the node from the list. Great for implementing Deques.

This routine also sets the CurrentNode field to point at the last node in
the list.

Include:stdlib.a or lists.a




Routine: InsertCur
-------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Pointer to node to insert

Examples of Usage:

lesdi, MyList
ldxiNewNode
InsertCur

Description:

InsertCur inserts the node pointed at by DX:SI before the "current" node in
the list. The current node is the last one operated on by the software.

The newly inserted node becomes the CurrentNode in the list.

Include:stdlib.a or lists.a




Routine: InsertmCur
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Pointer to data for node to insert

Flags on exit:Carry flag is set if malloc error occurs.

Examples of Usage:

lesdi, MyList
ldxiDataBlock
InsertmCur
jcError

Description:

InsertmCur builds a new node on the heap (using the block of data pointed at
by DX:SI and the size of a node in the size field of the list variable) and
then inserts the new node before the "current" node in the list. The current
node is the last one operated on by the software.

This code treats the newly inserted node as the current node.

Include:stdlib.a or lists.a



Routine: AppendCur
-------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Pointer to node to append

Examples of Usage:

lesdi, MyList
ldxiNewNode
AppendCur

Description:

AppendCur inserts the node pointed at by DX:SI after the "current" node in
the list. The current node is the last one operated on by the software.

The newly inserted node becomes the CurrentNode in the list.

Include:stdlib.a or lists.a




Routine: AppendmCur
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Pointer to data for node to insert.

Flags on exit:Carry flag is set if malloc error occurs.

Examples of Usage:

lesdi, MyList
ldxiDataBlock
AppendmCur
jcMallocError

Description:

AppendmCur builds a new node on the heap (using the block of data pointed at
by DX:SI and the size of a node in the size field of the list variable) and
then inserts the new node after the "current" node in the list. The current
node is the last one operated on by the software.

This code treats the newly inserted node as the current node.

Include:stdlib.a or lists.a



Routine: RemoveCur
-------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.

Registers on exit:DX:SI-Points at node removed from list (NIL if
no such node).

Flags on return:Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
RemoveCur
jcEmptyList

Description:

RemoveCur removes the current node (pointed at by CurrentNode) from the list
and returns a pointer to this node in DX:SI. If the list was empty, RemoveCur
returns NIL in DX:SI and sets the carry flag.

This routine modifies CurrentNode so that it points at the next item in the
list (the node normally following the current node). If there is no such
node (i.e., CurrentNode pointed at the last node in the list upon calling
RemoveCur) then this routine stores the value of the *previous* node into
CurrentNode. If you use this routine to delete the last node in the list,
it sets CurrentNode to NIL before leaving.

Include:stdlib.a or lists.a



Routine: PeekCur
-----------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.

Registers on exit:DX:SI-Points at the current node (i.e., contains
a copy of CurrentNode), NIL if the list
is empty.

Flags on return:Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
PeekCur
jcEmptyList

Description:

PeekCur simply returns CurrentNode in DX:SI (assuming the list is not empty).
If the list is empty, it returns the carry flag set and NIL in DX:SI.
It does not affect the value of CurrentNode.

Include:stdlib.a or lists.a



Routine: SetCur
----------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
CS-Node number of new current node.

Registers on exit:DX:SI-Returned pointing at selected node.
NIL if the list is empty. Points at the
last node in the list if the value in CX
is greater than the number of nodes in the
list.

Flags on return:Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
movcx, NodeNum
SetCur
jcEmptyList

Description:

SetCur locates the specified node in the list and sets CurrentNode to the
address of that node. It also returns a pointer to that node in DX:SI.
If CX is greater than the number of nodes in the list (or zero) then
SetCur sets CurrentNode to the last node in the list. If the list is
empty, SetCur returns NIL in DX:SI and returns with the carry flag set.

Include:stdlib.a or lists.a



Routine: Insert (m)
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Address of node to insert (Insert)
DX:SI-Pointer to data block to create node from
(Insertm).
CX-Number of node to insert DX:SI in front of;
Note that the list is one-based. That is,
the number of the first node in the list is
one. Zero corresponds to the last node in
the list.


Flags on return:Carry set if malloc error occurs (Insertm only).

Examples of Usage:

lesdi, MyList
ldxiNewNode
movcx, 5
Insert;Inserts before Node #5.

; The following example builds a new node on the heap from the data at
; location "RawData" and inserts this before node #5 in MyList.

lesdi, MyList
ldxiRawData
movcx, 5
Insertm
jcMallocError

Description:

Insert(m) inserts a new node before a specified node in the list. The node to
insert in front of is specified by the value in the CX register. The first
node in the list is node #1, the second is node #2, etc. If the value in
CX is greater than the number of nodes in the list (in particular, if CX
contains zero, which gets treated like 65,536) then Insert(m) appends the
new node to the end of the list.

Insertm allocates a new node on the heap (DX:SI points at the data fields
for the node). If a malloc error occurs, Insertm returns the carry flag
set.

CurrentNode gets set to the newly inserted node.

Include:stdlib.a or lists.a



Routine: Append (m)
--------------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
DX:SI-Address of node to insert (Append)
DX:SI-Pointer to data block to create node from
(Appendm).
CX-Number of node to insert DX:SI after;
Note that the list is one-based. That is,
the number of the first node in the list is
one. Zero corresponds to the last node in
the list.


Flags on return:Carry set if malloc error occurs (Appendm only).

Examples of Usage:

lesdi, MyList
ldxiNewNode
movcx, 5
Append;Inserts after Node #5.

; The following example builds a new node on the heap from the data at
; location "RawData" and inserts this after node #5 in MyList.

lesdi, MyList
ldxiRawData
movcx, 5
Appendm
jcMallocError

Description:

Append(m) inserts a new node after a specified node in the list. The node to
insert in front of is specified by the value in the CX register. The first
node in the list is node #1, the second is node #2, etc. If the value in
CX is greater than the number of nodes in the list (in particular, if CX
contains zero, which gets treated like 65,536) then Insert(m) appends the
new node to the end of the list.

Appendm allocates a new node on the heap (DX:SI points at the data fields
for the node). If a malloc error occurs, Appendm returns the carry flag
set.

CurrentNode gets set to the newly inserted node.

Include:stdlib.a or lists.a




Routine: Remove
----------------

Author: Randall Hyde

Category: List Manipulation

Registers on entry: ES:DI-Pointer to list.
CX-# of node to delete from list.

Registers on exit:DX:SI-Points at node removed from list (NIL if
no such node).

Flags on return:Carry set if the list was empty.

Examples of Usage:

lesdi, MyList
movcx, NodeNumbr
Remove
jcEmptyList

Description:

Remove removes the specified node (given by CX) from the list
and returns a pointer to this node in DX:SI. If the list was empty, Remove
returns NIL in DX:SI and sets the carry flag.

This routine modifies CurrentNode so that it points at the next item in the
list (the node normally following the current node). If there is no such
node (i.e., CurrentNode pointed at the last node in the list upon calling
Remove) then this routine stores the value of the *previous* node into
CurrentNode. If you use this routine to delete the last node in the list,
it sets CurrentNode to NIL before leaving.

Include:stdlib.a or lists.a