diff options
Diffstat (limited to 'private/crt32/string/i386/memchr.asm')
| -rw-r--r-- | private/crt32/string/i386/memchr.asm | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/private/crt32/string/i386/memchr.asm b/private/crt32/string/i386/memchr.asm new file mode 100644 index 000000000..3e20583c2 --- /dev/null +++ b/private/crt32/string/i386/memchr.asm @@ -0,0 +1,96 @@ + page ,132 + title memchr - search memory for a given character +;*** +;memchr.asm - search block of memory for a given character +; +; Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved. +; +;Purpose: +; defines memchr() - search memory until a character is +; found or a limit is reached. +; +;Revision History: +; 05-16-84 RN initial version +; 07-20-87 SKS rewritten for speed +; 05-17-88 SJM Add model-independent (large model) ifdef +; 08-04-88 SJM convert to cruntime/ add 32-bit support +; 08-23-88 JCR 386 cleanup +; 10-25-88 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 +;*** +;char *memchr(buf, chr, cnt) - search memory for given character. +; +;Purpose: +; Searched at buf for the given character, stopping when chr is +; first found or cnt bytes have been searched through. +; +; Algorithm: +; char * +; memchr (buf, chr, cnt) +; char *buf; +; int chr; +; unsigned cnt; +; { +; while (cnt && *buf++ != c) +; cnt--; +; return(cnt ? --buf : NULL); +; } +; +;Entry: +; char *buf - memory buffer to be searched +; char chr - character to search for +; unsigned cnt - max number of bytes to search +; +;Exit: +; returns pointer to first occurence of chr in buf +; returns NULL if chr not found in the first cnt bytes +; +;Uses: +; +;Exceptions: +; +;******************************************************************************* + + CODESEG + + public memchr +memchr proc \ + buf:ptr, \ + chr:byte, \ + cnt:IWORD + + xor eax,eax ; return NULL if cnt == 0 + + mov ecx,(cnt) ; cx = count + jecxz short empty + + push edi ; Preserve DI + + mov edi,buf ; di = buffer + mov al,chr ; al = search char + + repne scasb ; scan for byte + mov eax,0 ; assume not found (ax=NULL) + jne short done ; not found -- return NULL + lea eax,[edi-1] ; found - return address of matching byte +done: + pop edi ; Restore DI +empty: + +ifdef _STDCALL_ + ret DPSIZE + 2*ISIZE ; _stdcall return +else + ret ; _cdecl return +endif + +memchr endp + end |