Category : Assembly Language Source Code
Archive   : ASMLIB35.ZIP
Filename : SYSTEM.DOC

 
Output of file : SYSTEM.DOC contained in archive : ASMLIB35.ZIP

***************************** SYSTEM *************************************

ASMLIB system subroutines Copyright (C) 1991 - 1993 Douglas Herr
all rights reserved


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BREAKTRAP: initialize Ctrl+Break trap
BREAKRELEASE:restore previous Ctrl+Break handler
Source: break.asm

BREAKFLAG: public byte in DGROUP, indicating Ctrl+Break key press
Source: asmflags.asm

Call with: no parameters
BreakTrap uses well-behaved methods to trap Ctrl+Break,
Ctrl+C and Ctrl-Alt-Del key sequences. When one of these
key combinations is pressed, ASMLIB's break trap sets the
public flag "breakflag" in the data area. BreakRelease
de-activates ASMLIB's break trap, restoring the previous
Ctrl+Break handler. BreakFlag = 0 until a monitored key
combination is pressed, at which time breakflag is set
equal to 1. If you use BreakTrap, you MUST call BreakRelease
before the end of your program, or you will find yourself
reaching for the Big Red Switch. See STARTUP.ASM.
Returns: nothing
Uses: nothing
Example: see STARTUP.ASM



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COLOR16: calculate color value for palette register
Source: color16.asm

Call with: DS:[BX] pointing to red value (0-3), green value (0-3)
and blue value (0-3)
Assumes DS:@data; see also Palette16
Returns: AH = color value for 16-color palette register
Uses: AH
Supports: VGA 16-color modes (text or graphics)
EGA 16-color modes, except with CGA monitor
Example:

.data
c16 db 3 ; brightest red
db 1 ; dim green
db 0 ; no blue

.code
; program fragment assumes DS:@data
.
.
.
lea bx,c16
call color16



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DOSALLOC: allocate memory block from unused DOS memory
Source: dosalloc.asm

Call with: DX:AX = number of bytes to allocate
DOSAlloc uses DOS function 48h to allocate memory from free
DOS memory. See ENDPROG and STARTUP.ASM or TINY.ASM.
Returns: if CF = 0, AX = segment address of start of memory block
offset of start of memory block = 0
if CF = 1, insufficient DOS memory space is available.
Uses: AX, CF; all other flags and registers are saved
Example:

.model huge

extrn bitblockbytes:proc, dosalloc:proc

.code
; this example uses bitblockbytes to calculate the memory required
; to save a bit block on a graphics screen
.
.
.
lea bx,corners ; point to bit block corner coordinates
call bitblockbytes ; returns DX:AX = number of bytes required
call dosalloc
jc no_memory ; do some error handling stuff



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ENDPROG: determines program's size
this is handy for dynamic memory allocation, or for TSR work
Source: endprog.asm

Call with: no parameters
Returns: (small, medium, huge models)
AX = segment address of end of program. See STARTUP.ASM.
ENDPROG defines ZSEG as the last segment in the program.
If you add any object modules to ASMLIB.LIB, be certain any
segments in the added modules are defined before LINK
encounters ENDPROG. Be sure to review the .MAP file after
linking. ZSEG should be at the end of the program.
(tiny model)
AX = offset of end of the program's code and initialized data.
See TINY.ASM startup code. If you add any object modules to
ASMTINY.LIB, be certain any segments in the added modules
are defined before LINK encounters ENDPROG, and that all
segments are grouped in DGROUP. Be sure to review the .MAP
file after linking. ZSEG should be at the end of the program.
With TINY model, program stack extends beyond the end of the
code and initialized data to the end of the 64k program
segment.
Uses: AX
Example: see STARTUP.ASM or TINY.ASM


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EXENAME: determine the full path and filename of the executing program
Source: exename.asm (strlen.asm)

Call with: ES = PSP segment (see STARTUP.ASM)
Returns: ES:[BX] pointing to the the name of the executing program,
including drive and full path, CX = length of the filename.
The filename returned is an ASCIIZ string, and may be mixed
upper- and lower-case characters.
Uses: ES, BX, CX; all other registers and flags are saved.
Example:

include asm.inc

extrn exename:proc

.data
extrn pspseg:word

.code
; program fragment assumes DS:@data
.
.
.
mov es,pspseg
call exename ; string returned at ES:[BX] can be
; copied to heap with STRNDUP



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FARALLOC: allocate memory from a far heap
Source: farheap.asm

Call with: ES = segment address of far heap
AX = requested block size
Returns: if CF = 1, insufficient memroy available in heap
if CF = 0, ES:[BX] = starting address of allocated memory
Uses: BX, flags
Example: see FarInit


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FARFREE: releases far heap memory previously allocated
Source: farheap.asm

Call with: ES:[BX] pointing to memory block to be released
Returns: nothing
Uses: AX, BX, flags
Example: mov es,heap_seg
mov bx,pointer
call farfree


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FARINIT: initializes a far heap
Source: farheap.asm

Call with: ES = segment address of memory block to be managed by ASMLIB's
far heap manager
AX = size of memory block in bytes (2 < bytes < 32768)
FarInit assumes that the memory block begins at ES:[0].
Any number of far heaps may be used if memory is available.
Returns: if CF = 0, successful; if CF = 1, AX is out of range.
Uses: flags
Example:

include asm.inc

extrn dosalloc:proc, farinit:proc

.data
heap_seg dw ?

.code
.
.
.
mov ax,32767
xor dx,dx ; allocate 32k from DOS memory
push ax
call dosalloc
mov heap_seg,ax ; segment address of allocated block
pop ax ; size of block
jc not_enough_dos ; insufficient memory available
mov es,heap_seg
call farinit ; initialize this block
.
.
mov ax,125 ; get 125 bytes from far heap
mov es,heap_seg ; heap address
call faralloc ; get far memory; returned at ES:[BX]
jc not_enough_heap



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FARREALLOC: re-sizes a block of memory in a far heap
Source: farheap.asm

Call with: ES:[BX] = original pointer to memory block
AX = new byte size
Returns: if successful, CF = 0, ES:[BX] points to new block
if not successful, CF = 1
Uses: BX, flags
Example: mov es,heap_seg
mov bx,pointer
mov ax,newsize
call farrealloc


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FINDMONO: detects a monochrome-compatible video card
this is handy in 2-monitor systems.
Source: findmono.asm (a$herc.asm, isega.asm, find6845.asm)

Call with: no parameters
Returns: if CF = 1, no monochrome monitor
if CF = 0, AX = monitor code
0 = MDA
0101h = EGA monochrome
0301h = VGA monochrome
128 = Hercules or clone
144 = Hercules Graphics Card plus
208 = Hercules InColor
Uses: AX, CF
Supports: MDA, EGA & VGA MONO, HGC, HGC+, InColor
Example: call findmono
jc no_monochrome



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FLOPPIES: determine the number of floppy disk drives intalled
Source: floppies.asm

Call with: no parameters
Returns: AX = number of floppy drives
Uses: AX; all other registers and flags are saved
Example:

.model medium

public myproc
extrn floppies:proc

.code
myproc proc
.
call floppies



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FLOPPYTYPE: determine the number of floppy disk drives intalled
Source: floptype.asm

Call with: DL = drive number (0 = drive A:)
Returns: AX = floppy drive type
0 = invalid drive number
1 = 360k
2 = 1.2M
3 = 720k
4 = 1.44M
Uses: AX, flags
Example:

.model medium

public myproc
extrn floppytype:proc

.data
drive_number db 0

.code
myproc proc
.
mov dl,drive_number
call floppytype
or ax,ax
jz bad_drive_number

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GETCPU: detects cpu type
Source: getcpu.asm

Call with: no parameters
Returns: AX = 0 if 8086/8088
AX = 1 if 80186/80188
AX = 2 if 80286
AX = 3 if 386 (SX or DX)
AX = 4 if 486 (SX or DX)
Uses: AX
Example: call getcpu



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GETCRT: determines active monitor type
Source: getcrt.asm (a$herc.asm, isevga.asm)

Call with: no parameters
Returns: AX = code for active video system
CGA = -1
MDA = 0
EGA mono = 0100h
VGA mono = 0300h
EGA color = 1
MCGA = 2
VGA color = 3
HGC = 128
HGC+ = 144
InColor = 208
Note: GetCRT may be re-assembled with the /DNOHERC switch
to eliminate code which detects Hercules equipment
Uses: AX
Supports: CGA, MCGA, MDA, HGC, HGC+, InColor, EGA, VGA
Example: call getcrt



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HALLOC: allocates memory from near heap
Source: heap.asm

Call with: AX = bytes requested; assumes DS:@data
heap must be initialized with hinit
Returns: if space available:
BX = near pointer for allocated data
if space not available:
CF = 1
Uses: AX, BX, flags
Example: mov ax,bytes
call halloc
jc no_memory ; check to see if there was enough space


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HFREE: releases heap memory previously allocated
Source: heap.asm

Call with: BX = near pointer to memory block; assumes DS:@data
Returns: nothing
Uses: flags
Example: mov bx,pointer
call hfree



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HINIT: initializes heap manager
Source: heap.asm

Call with: AX = number of bytes to be managed by heap manager
2 <=bytes<= 32767
BX = near pointer to memory block to be managed
assumes DS:@data
Returns: CF = 0 if ok, CF = 1 if bad parameter (bytes too
small or too large)
Uses: flags
Example:

.data
heap db 32767 dup(0)

.code
mov ax,@data
mov ds,ax
assume ds:@data
mov ax,32767
lea bx,heap
call hinit


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HMAX: determines largest free block in asmlib's near heap
Source: heap.asm

Call with: no parameters
Returns: AX = block size in bytes
AX = -1 if the heap has not been initialized
Uses: AX
Example: call hmax



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HREALLOC: re-sizes a block of memory in the near heap
Source: heap.asm

Call with: BX = original pointer to memory block
AX = new byte size
Returns: if successful, CF = 0, BX = new block pointer
if not successful, CF = 1
Uses: BX, flags
Example: mov bx,pointer
mov ax,newsize
call hrealloc


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ISANSI: determines if ANSI or compatible is loaded and active
Source: isansi.asm

Parameters: none
Returns: CF = 1 if no ANSI device driver loaded and active
CF = 0 if ANSI loaded and active
Uses: CF
Example: call isansi ; let's see if ansi.sys is loaded
jc no_ansi ; jump if not



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ISATT: determines if an ATT 6300-type display card is installed
this equipment is like a CGA except that it has an additional
640 x 400 2-color graphics mode (mode 40h)
Source: isatt.asm ($6845.asm, isevga.asm)


Call with: no parameters
Returns: if CF = 1, ATT 6300 display not present
if CF = 0, ATT 6300 display is installed
Uses: flags
Example:

include asm.inc

public cgamode

extrn isatt:proc

.code
cgamode proc
mov ax,06h ; default: set CGA mode
call isatt ; see if mode 40h is available
jc set_mode ; nope
mov ax,40h ; use ATT 6300 mode 40h
set_mode:
push bp ; required by old PC BIOS
int 10h ; use BIOS to set mode
pop bp
ret
cgamode endp
end


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ISEVGA: determines if an EGA or VGA is installed
Source: isevga.asm

Call with: no parameters
Returns: if CF = 1, no EGA or VGA
if CF = 0
DX = video memory in kbytes
AL = monitor type
AL = -1 if monitor is CGA
AL = 0 if monitor is monochrome
AL = 1 if monitor is EGA or better

AH = EGA/VGA flag
AH = 1 if EGA
AH = 3 if VGA

Uses: AX, DX, CF
Example: call isevga
jc no_evga



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ISHERC: determines if a Hercules card or compatible is installed
and if so, determines if it is the active video system.
Source: isherc.asm (a$herc.asm)

Call with: no parameters
Returns: if CF = 1, no Hercules or compatible installed
if CF = 0, AX = Hercules model
128 = Hercules Graphics Card or compatible; active
144 = Hercules Graphics Card Plus; active
208 = Hercules InColor card; active
-128 = Hercules Graphics Card or compatible; not active
-144 = Hercules Graphics Card Plus; not active
-208 = Hercules InColor card; not active
Uses: AX, CF; all other flags and registers are saved
Example: call isherc
jc no_herc



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ISMOUSE: determines if a mouse is installed
Source: ismouse.asm (asmflags.asm)

Parameters: none
Returns: AX = number of mouse buttons
AX = 0 if no mouse or mouse driver installed
Uses: AX
Example:

include asm.inc

.code
.
.
.
call ismouse
or ax,ax
jz no_mouse



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ISSEVGA: determines if a Super EGA or Super VGA is installed
Source: issevga.asm

Parameters: none
Returns: if CF = 1, no Super EGA or Super VGA recognized by ASMLIB

if CF = 0

if AH = 1: (Super EGA)
AL = 1 if Paradise EGA 480
AL = 2 if Everex EGA

if AH = 3: (Super VGA)
AL = 1 if Paradise VGA
AL = 3 if Tseng VGA chipset
AL = 4 if Oak VGA
AL = 5 if Western Digital VGA chipset

See also IsEVGA
Uses: AX, CF
Example: call issevga
jc no_superevga



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MATHCHIP: determines if 80x87 math coprocessor is installed
Source: mathchip.asm

Parameters: none
Returns: AX = code for 80x87 model
0 = not installed
1 = 8087
2 = 287
3 = 387 (DX or SX)
4 = 487 (486DX or 487SX)
If the coprocessor is present, it is initilaized by MathChip.
Uses: AX, all 80x87 registers
Example: call mathchip



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MOUSEINIT: initializes mouse driver if mouse present
Source: mouseini.asm

MOUSEFLAG: public byte in DGROUP indicating mouse buttons
Source: asmflags.asm

Parameters: assumes DS:@data
Returns: if mouse installed, ZF = 0 and AX = number of mouse buttons
also updates mouseflag
if no mouse, ZF = 1 and AX = 0
Uses: AX, flags
Example:

include asm.inc

extrn mouseinit:proc

.code
; program fragment assumes DS:@data
.
.
.
call mouseinit
jz no_mouse



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MSAVE: save mouse state
Source: msave.asm (dosalloc.asm)

MRESTORE: restore previously saved mouse state
Source: msave.asm (dosalloc.asm)

MSave and MRestore are handy when you have installed a
mouse event handler and you will be using the SYSTEM command,
where some other program may reset or otherwise change the
mouse event trapping.

MSave allocates a buffer, saves the mouse state in the
buffer, resets the mouse driver and returns the buffer address.

MRestore restores a specified mouse state and releases the
buffer. Both MSave and MRestore assume that you already
know there is a mouse in the system.

Call with: MSAve: no paramerters
MRestore: AX = buffer address returned by prior MSave call
Returns: if CF = 1, AH = MS-DOS error code
if CF = 0, no error; MSave returns buffer address in AX
Uses: AX, flags
Example:

include asm.inc
extrn msave:proc, mrestore:proc

.data
save_mouse dw 0

.code
; program fragment assumes DS:@data
.
.
.

; save the mouse driver state
; I've already checked to see if there's a mouse
call msave
jc dos_error
mov save_mouse,ax
.
.
; some other subroutine has messed with the mouse
mov ax,save_mouse ; buffer address from previous MSave
call mrestore
jc dos_error



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PALETTE16: change palette in EGA, VGA or SVGA 16-color mode
changing the palette changes the actual color associated
with a color attribute
Source: palet16.asm

Call with: BH = color value (see Color16 in SYSTEM.DOC)
BL = color attribute to map color to (0-0Fh)
restore default palette with BH = BL = 0FFh
Returns: nothing
Uses: nothing
Example:

.data
c16 db 3 ; brightest red
db 1 ; dim green
db 0 ; no blue

.code
; program fragment assumes DS:@data
.
.
.
lea bx,c16
call color16
mov bh,ah ; color value in BH
mov bl,15 ; color attribute 0Fh
call palette16



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SYSTEM: execute a second copy of COMMAND.COM; optionally runs another
program.
Source: system.asm (strlen.asm)

Parameters: ES = PSP segment
DS:[BX] points to command tail
if DS:[BX] points to a nul byte, control is transfered
to the second copy of COMMAND.COM and you get a DOS prompt.
control is passed back to the calling program when EXIT is
entered at the DOS prompt.

if DS:[BX] points to an ASCIIZ string with the name of a
program (and optional command line parameters), the program
will be executed, and control will pass back to the calling
program at the termination of the second program.
Returns: nothing
Uses: AX
Example:

include asm.inc

; I want to go to DOS temporarily to format a 720k disk
extrn system:proc

.data
; PSP segment is saved here by my startup code
pspseg dw ?
cmdtail db 'format a: /n:9 /t:80',0

.code
; program fragment assumes DS:@data
.
.
lea bx,cmdtail ; DS:[BX] points to command tail
mov es,pspseg
call system


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USE32K: limit Hercules equipment to 32k memory (128k on InColor)
USE64K: allow full 64k on HGC and HGC+ (256k on InColor)
Source: a$herc.asm

Requires Hercules or compatible

Call with: no parameters
Use32k is equivalent to the Hercules "half" configuration
Use64k is equivalent to the Hercules "full" configuration
ASMLIB's default is "half". Use this configuration if you
have a 2-monitor system, unless you are using the Hercules
CGA card.
Returns: nothing
Uses: nothing
Example: ; in this example I'm determining if a Hercules is installed
; and setting the configuration to "full"
extrn IsHerc:proc
extrn Use64k:proc
.code
.
.
.
call IsHerc
jc no_herc
or ax,ax
js use_only_half ; use_only_half if HGC is not default monitor
call use64k ; else use all Hercules memory
use_only_half:




  3 Responses to “Category : Assembly Language Source Code
Archive   : ASMLIB35.ZIP
Filename : SYSTEM.DOC

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