Category : Pascal Source Code
Archive   : FINDMEM.ZIP
Filename : FINDMEM.ASM

;*****************************************************************************
;
;Written 11-5-88 by Jeff Mock user id 74106,1031
;Leave me a message if you can think of any enhancements to this code
;
; Function FindMem(Segment,Offset,Count:word;
; Search:string;
; var Location:dword) : boolean;
;
;Purpose: Search for a byte or string of bytes in any memory segment
;
;Assembled with borland turbo assembler 1.0
;
;Example for use with borland turbo pascal 5.0
;
;Program test;
;
;var Location:word;
; t:boolean;
;
;{$F+}
;function FindMem(Seg_Ment,Off_set,Count:word;s:string;var Location:word) : boolean; external;
;{$L findmem.obj}
;{$f-}
;
;begin
; t:=FindMem(0,0,$ffff,'NUL',Location);
; if t then writeln('String "NUL" found at segment 0 offset decimal ',Location);
;end.
;
;This can be rewritten as a near function depending on where you are going
;to place it in your program
;
;*****************************************************************************

.model TPASCAL
.CODE
FindMem PROC FAR Seg_ment:WORD,Off_set:WORD,Count:WORD,String:DWORD,Location:DWORD
PUBLIC FindMem
mov es,Seg_ment ;Get search segment
mov dx,Off_set ;Get starting offset in segment
mov cx,Count ;Get search count
mov bx,ds ;Save data segment
cont:
lds si,string ;Get segment/offset to search string
inc si ;Increment past string length byte
mov di,dx ;set offset address
mov al,[si] ;Get first search string character
cld ;Set direction flag to foward
repnz scasb ;Search for byte
jcxz nomatch ;Jump if not found
mov dx,di ;Else save current segment offset
dec di ;Point offset back to found byte
xor ax,ax ;Zero ax
push ds ;Save segment/offset temp.
push si
lds si,string ;Point back to string start
mov al,[si] ;Get length byte
pop si ;Restore segment/offset
pop ds
inc ax ;Increment length count
xchg cx,ax ;Exchange count values
rep cmpsb ;Compare bytes from string and memory
jcxz found ;Jump if bytes match
xchg cx,ax ;Else restore segment count to cx
jmp cont ;Continue search untill string found or count=0
nomatch:
mov al,0 ;Set function boolean to false/string not found
jmp exit ;Exit function
found:
dec dx ;Set up string offset location/string found
lds si,Location ;Get varible storage location
mov [si],dx ;Save found string offset location in varible
mov al,1 ;Set function to true/string found
exit:
mov ds,bx ;Restore programs data segment
ret ;Return to caller
FindMem ENDP

CODE ENDS

END