Category : C++ Source Code
Archive   : VCCRT2.ZIP
Filename : MEMICMP.ASM

page ,132
title memicmp - compare blocks of memory, ignore case
;***
;memicmp.asm - compare memory, ignore case
;
; Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
;
;Purpose:
; defines memicmp() - compare two blocks of memory for lexical
; order. Case is ignored in the comparison.
;
;*******************************************************************************

.xlist
include version.inc
include cmacros.inc
.list

sBegin code
assumes cs,code
assumes ds,data

page
;***
;int _memicmp(first, last, count) - compare two blocks of memory, ignore case
;
;Purpose:
; Compares count bytes of the two blocks of memory stored at first
; and last. The characters are converted to lowercase before
; comparing (not permanently), so case is ignored in the search.
;
; Algorithm:
; int
; _memicmp (first, last, count)
; char *first, *last;
; unsigned count;
; {
; if (!count)
; return(0);
; while (--count && tolower(*first) == tolower(*last))
; {
; first++;
; last++;
; }
; return(tolower(*first) - tolower(*last));
; }
;
;Entry:
; char *first, *last - memory buffers to compare
; unsigned count - maximum length to compare
;
;Exit:
; returns <0 if first < last
; returns 0 if first == last
; returns >0 if first > last
;
;Uses:
;
;Exceptions:
;
;*******************************************************************************

ifdef MODELINDEP

cProc _fmemicmp,,

else

cProc _memicmp,,

endif

parmdp first
parmdp last
parmw count

cBegin

if sizeD
push ds ; save ds
lds si,first ; ds:si=pointer to first
les di,last ; es:di=pointer to last
else
mov si,first ; si=pointer to first
mov di,last ; di=pointer to last
push ds ; fix es for small/middle model
pop es
endif

mov cx,count
jcxz toend ; if count=0

mov bh,'A'
mov bl,'Z'
mov dh,'a'-'A' ; add to cap to make lower

lupe:
mov ah,[si] ; *first

if sizeD
mov al,es:[di] ; *last
else
mov al,[di] ; *last
endif

inc si ; first++
inc di ; last++

cmp ah,bh ; 'A'
jb skip1

cmp ah,bl ; 'Z'
ja skip1

add ah,dh ; make lower case

skip1:
cmp al,bh ; 'A'
jb skip2

cmp al,bl ; 'Z'
ja skip2

add al,dh ; make lower case

skip2:
cmp ah,al ; characters different ??
jne differ

loop lupe
jmp short toend ; cx = 0, return 0

differ:
mov cx,-1 ; assume last is bigger
jb short toend ; last is, in fact, bigger (return -1)
neg cx ; first is bigger (return 1)

toend:
mov ax,cx

if sizeD
pop ds ; restore ds
endif

cEnd

sEnd
end