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kolibrios/programs/develop/open watcom/trunk/clib/string/fstrstr.c
Sergey Semyonov (Serge) 836c97f0ac Clib string & memory functions
git-svn-id: svn://kolibrios.org@553 a494cfbc-eb01-0410-851d-a64ba20cac60
2007-06-26 00:54:22 +00:00

94 lines
3.1 KiB
C

/****************************************************************************
*
* Open Watcom Project
*
* Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
* ========================================================================
*
* This file contains Original Code and/or Modifications of Original
* Code as defined in and that are subject to the Sybase Open Watcom
* Public License version 1.0 (the 'License'). You may not use this file
* except in compliance with the License. BY USING THIS FILE YOU AGREE TO
* ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
* provided with the Original Code and Modifications, and is also
* available at www.sybase.com/developer/opensource.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
* NON-INFRINGEMENT. Please see the License for the specific language
* governing rights and limitations under the License.
*
* ========================================================================
*
* Description: _fstrstr() implementation.
*
****************************************************************************/
#include "variety.h"
#include <stddef.h>
#include <string.h>
#ifdef M_I86
#if defined(__QNX__)
#include <i86.h>
#else
#include <dos.h>
#endif
extern int i86_memeq( const char _WCFAR *, const char _WCFAR *, int );
#define _ZFLAG (INTR_ZF<<8)
#pragma aux i86_memeq = \
0x1e /* push ds */\
0x96 /* xchg si,ax */\
0x8e 0xd8 /* mov ds,ax */\
0xf3 0xa6 /* rep cmpsb */\
0x9f /* lahf */\
0x1f /* pop ds */\
parm caller [si ax] [es di] [cx]\
value [ax] \
modify exact [si di cx ax];
#define memeq( p1, p2, len ) ( i86_memeq((p1),(p2),(len)) & _ZFLAG )
#else
#define memeq( p1, p2, len ) ( _fmemcmp((p1),(p2),(len)) == 0 )
#endif
/* Locate the first occurrence of the string pointed to by s2 in the
string pointed to by s1.
The strstr function returns a pointer to the located string, or a
null pointer if the string is not found.
*/
_WCRTLINK char _WCFAR *_fstrstr( const char _WCFAR *s1, const char _WCFAR *s2 )
{
char _WCFAR *end_of_s1;
size_t s1len, s2len;
if( s2[0] == '\0' ) {
return( (char _WCFAR *)s1 );
} else if( s2[1] == '\0' ) {
return( _fstrchr( s1, s2[0] ) );
}
end_of_s1 = _fmemchr( s1, '\0', ~0u );
s2len = _fstrlen( s2 );
for(;;) {
s1len = end_of_s1 - s1;
if( s1len < s2len ) break;
s1 = _fmemchr( s1, *s2, s1len ); /* find start of possible match */
if( s1 == NULL ) break;
if( memeq( s1, s2, s2len ) ) return( (char _WCFAR *)s1 );
++s1;
}
return( NULL );
}