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Diffstat (limited to 'private/crt32/string/i386/strncmp.asm')
| -rw-r--r-- | private/crt32/string/i386/strncmp.asm | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/private/crt32/string/i386/strncmp.asm b/private/crt32/string/i386/strncmp.asm new file mode 100644 index 000000000..15b187651 --- /dev/null +++ b/private/crt32/string/i386/strncmp.asm @@ -0,0 +1,120 @@ + page ,132 + title strncmp - compare first n chars of two strings +;*** +;strncmp.asm - compare first n characters of two strings +; +; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved. +; +;Purpose: +; defines strncmp() - compare first n characters of two strings +; for lexical order. +; +;Revision History: +; 10-26-83 RN initial version +; 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 +; 10-26-88 JCR General cleanup for 386-only code +; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright. +; 05-10-91 GJF Back to _cdecl, sigh... +; +;******************************************************************************* + + .xlist + include cruntime.inc + .list + +page +;*** +;int strncmp(first, last, count) - compare first count chars of strings +; +;Purpose: +; Compares two strings for lexical order. The comparison stops +; after: (1) a difference between the strings is found, (2) the end +; of the strings is reached, or (3) count characters have been +; compared. +; +; Algorithm: +; int +; strncmp (first, last, count) +; char *first, *last; +; unsigned count; +; { +; if (!count) +; return(0); +; while (--count && *first && *first == *last) +; { +; first++; +; last++; +; } +; return(*first - *last); +; } +; +;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 strncmp +strncmp proc \ + uses edi esi ebx, \ + first:ptr byte, \ + last:ptr byte, \ + count:IWORD + + + mov ecx,[count] ; cx=max number of bytes to compare + jecxz short toend ; it's as if strings are equal + + mov ebx,ecx ; bx saves count + + mov edi,[first] ; di=first pointer (es=segment part) + + mov esi,edi ; si saves first pointer + xor eax,eax ; ax=0 +repne scasb ; count bytes + neg ecx ; cx=count - strlen + add ecx,ebx ; strlen + count - strlen + +okay: + mov edi,esi ; restore first pointer + mov esi,[last] ; si = last pointer +repe cmpsb ; compare strings + mov al,[esi-1] + xor ecx,ecx ; set return value = 0 + + cmp al,[edi-1] ; last-first + ja short lastbig ; <last is bigger> + je short toend ; <equal> + ;jb short firstbig ; <first is bigger> + +firstbig: + dec ecx ; first string is bigger + dec ecx ; make FFFE so 'not' will give 0001 + +lastbig: ; last string is bigger + not ecx ; return -1 + +toend: + mov eax,ecx ; return value + +ifdef _STDCALL_ + ret 2*DPSIZE + ISIZE ; _stdcall return +else + ret ; _cdecl return +endif + +strncmp endp + end |