Category : Pascal Source Code
Archive   : TBTREE16.ZIP
Filename : MATH.PAS

(* TBTree16 Copyright (c) 1988,1989 Dean H. Farwell II *)

unit Math;

(*****************************************************************************)
(* *)
(* M A T H M A T I C A L R O U T I N E S *)
(* *)
(*****************************************************************************)


(* These routines augment the Turbo Pascal routines provided.


(* Version Information

Version 1.1 - No Changes

Version 1.2 - No Changes

Version 1.3 - Modified 11 July 1988 by Jack Dolby
Gately Communication Company
501 Industry Drive
Hampton, VA 23661

These are inline assembly language macros to perform the same function
as the Pascal versions in versions prior to 1.3.

Note that the entire code for inline macros must be in the INTERFACE
section. The code in these macros is actually placed in the code the
compiler emits at each place they are invoked. This results in larger
code but eliminates the time overhead for calling a routine and
returning from it. Only the pushing of parameters and extracting the
functional result are done rather than also pushing the return address,
preserving registers in the code, setting up a stack frame, and
restoring all registers and the stack on return. This results in
faster code at the expense of code size (if called from more than one
place) and in loosing the ability to hide the code in the
IMPLEMENTATION SECTION. j. dolby

My special thanks goes to j. dolby who took the time to make these
improvements and graciously allowed me to include them for
distribution!! Dean H. Farwell II

Version 1.4 - Jack Dolby modified (cleaned up) all routines for this
version

- Deleted PowerInt routine since it is not really used for
anything

Version 1.5 - No Changes

Version 1.6 - No Changes *)

(*\*)
(*////////////////////////// I N T E R F A C E //////////////////////////////*)

interface

(* the following type supports the byte handling routine(s) *)

type
BytePosition = 0 .. 7;
BitValue = 0 .. 1;


(* This function will determine if a certain bit within a target byte is
toggled on (equal to 1). The bit position is is the position within the
byte of the bit to be tested. The least significant bit is 0 then most
significant bit is 7. If the bit is 1 TRUE will be returned. If the bit
is 0 FALSE will be returned. Notice that the target byte can be of any
type. in this way, the routine will handle any a bit byte. In other
words a character could also be passed in. *)

(* Boolean functions return zero flag set and AL=0 for false,
zero flag reset and AL=1 for true *)

function BitOn(var targetByte;
bitNum : BytePosition ):boolean;

(* pop cx ;bitNum
pop bx ;offset of targetByte
pop es ;segment of targetByte
mov al, byte ptr es:[bx] ;get the byte
shr al,cl ;get desired bit
;in rightmost position
and al,01 ;check for bit set *)

INLINE($59/$5B/$07/$26/$8A/$07/$D2/$E8/$24/$01);


(*\*)
(* This will set a given bit to a value of zero or one depending on what is
passed in as the last parameter. See above for description of the other
parameters *)

procedure SetBit(var targetByte;
bitNum : BytePosition;
bit : BitValue );

(* pop ax ;bit
pop cx ;bitNum
pop bx ;offset of targetByte
pop es ;segment of targetByte
mov ah,11111110b ;mask to reset
rol ah,cl ;get it in place
and byte ptr es:[bx],ah ;reset regardless
shl al,cl ;mask to set/reset
or byte ptr es:[bx],al ;make bit proper value *)

INLINE($58/$59/$5B/$07/$B4/$FE/$D2/$C4/$26/$20/$27/$D2/$E0/$26/$08/$07);














(*!*)
(*///////////////////// I M P L E M E N T A T I O N /////////////////////////*)

implementation

end. (* end of Math unit *)