2025-04-27 07:49:33 -04:00

154 lines
3.4 KiB
NASM

page ,132
title strnicmp - compare n chars of strings, ignore case
;***
;strnicmp.asm - compare n chars of strings, ignoring case
;
; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
;
;Purpose:
; defines _strnicmp() - Compares at most n characters of two strings,
; without regard to case.
;
;Revision History:
; 04-04-85 RN initial version
; 07-11-85 TC zeroed cx, to allow correct return value if not equal
; 05-18-88 SJM Add model-independent (large model) ifdef
; 08-04-88 SJM convert to cruntime/ add 32-bit support
; 08-23-88 JCR 386 cleanup and improved return value sequence
; 10-26-88 JCR General cleanup for 386-only code
; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright.
; 01-18-91 GJF ANSI naming.
; 05-10-91 GJF Back to _cdecl, sigh...
;
;*******************************************************************************
.xlist
include cruntime.inc
.list
page
;***
;int _strnicmp(first, last, count) - compares count char of strings, ignore case
;
;Purpose:
; Compare the two strings for lexical order. Stops the comparison
; when the following occurs: (1) strings differ, (2) the end of the
; strings is reached, or (3) count characters have been compared.
; For the purposes of the comparison, upper case characters are
; converted to lower case.
;
; Algorithm:
; int
; _strncmpi (first, last, count)
; char *first, *last;
; unsigned int count;
; {
; int f,l;
; int result = 0;
;
; if (count) {
; do {
; f = tolower(*first);
; l = tolower(*last);
; first++;
; last++;
; } while (--count && f && l && f == l);
; result = f - l;
; }
; return(result);
; }
;
;Entry:
; char *first, *last - strings to compare
; unsigned count - maximum number of characters to compare
;
;Exit:
; returns <0 if first < last
; returns 0 if first == last
; returns >0 if first > last
;
;Uses:
;
;Exceptions:
;
;*******************************************************************************
CODESEG
public _strnicmp
_strnicmp proc \
uses edi esi ebx, \
first:ptr byte, \
last:ptr byte, \
count:IWORD
mov esi,[first] ; si = first string
mov edi,[last] ; di = last string
mov ecx,[count] ; cx = byte count
jecxz short toend ; if count=0
mov bh,'A'
mov bl,'Z'
mov dh,'a'-'A' ; add to cap to make lower
lupe:
mov ah,[esi] ; *first
mov al,[edi] ; *last
or ah,ah ; see if *first is null
jz short eject ; jump if so
or al,al ; see if *last is null
jz short eject ; jump if so
inc esi ; first++
inc edi ; last++
cmp ah,bh ; 'A'
jb short skip1
cmp ah,bl ; 'Z'
ja short skip1
add ah,dh ; make lower case
skip1:
cmp al,bh ; 'A'
jb short skip2
cmp al,bl ; 'Z'
ja short skip2
add al,dh ; make lower case
skip2:
cmp ah,al ; *first == *last ??
jne short differ
loop lupe
eject:
xor ecx,ecx
cmp ah,al ; compare the (possibly) differing bytes
je short toend ; both zero; return 0
differ:
mov ecx,-1 ; assume last is bigger (* can't use 'or' *)
jb short toend ; last is, in fact, bigger (return -1)
neg ecx ; first is bigger (return 1)
toend:
mov eax,ecx
ifdef _STDCALL_
ret 2*DPSIZE + ISIZE ; _stdcall return
else
ret ; _cdecl return
endif
_strnicmp endp
end