kolibrios-gitea/programs/develop/open watcom/trunk/clib/string/strstr.c

114 lines
3.7 KiB
C
Raw Normal View History

/****************************************************************************
*
* 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: Implementation of strstr() and wcsstr().
*
****************************************************************************/
#include "variety.h"
#include "widechar.h"
#include <stddef.h>
#include <string.h>
#if defined(_M_IX86)
#include <i86.h>
#endif
#if defined(M_I86) && !defined( __WIDECHAR__ )
extern int i86_memeq( const char *, const char _WCFAR *, int );
#define _ZFLAG (INTR_ZF<<8)
#if defined(__SMALL_DATA__)
#pragma aux i86_memeq = \
0xf3 0xa6 /* rep cmpsb */\
0x9f /* lahf */\
parm caller [si] [es di] [cx]\
value [ax] \
modify exact [si di cx ax];
#else
#pragma aux i86_memeq = \
0x1e /* push ds */ \
0x8e 0xda /* mov ds,dx */ \
0xf3 0xa6 /* rep cmpsb */\
0x9f /* lahf */\
0x1f /* pop ds */ \
parm caller [dx si] [es di] [cx]\
value [ax] \
modify exact [si di cx ax];
#endif
#define memeq( p1, p2, len ) ( i86_memeq((p1),(p2),(len)) & _ZFLAG )
#else
#define memeq( p1, p2, len ) ( memcmp((p1),(p2),(len)*CHARSIZE) == 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_TYPE *__F_NAME(strstr,wcsstr) ( const CHAR_TYPE *s1, const CHAR_TYPE *s2 )
{
CHAR_TYPE *end_of_s1;
size_t s1len, s2len;
if( s2[0] == NULLCHAR ) {
return( (CHAR_TYPE *)s1 );
} else if( s2[1] == NULLCHAR ) {
return( __F_NAME(strchr,wcschr)( s1, s2[0] ) );
}
#ifdef __WIDECHAR__
end_of_s1 = (CHAR_TYPE*)s1 + wcslen( s1 );
#else
end_of_s1 = memchr( s1, NULLCHAR, ~0u );
#endif
s2len = __F_NAME(strlen,wcslen)( s2 );
for(;;) {
s1len = end_of_s1 - s1;
if( s1len < s2len ) break;
#ifdef __WIDECHAR__
s1 = wcschr( s1, *s2 ); /* find start of possible match */
#else
s1 = memchr( s1, *s2, s1len ); /* find start of possible match */
#endif
if( s1 == NULL ) break;
if( memeq( s1, s2, s2len ) ) return( (CHAR_TYPE *)s1 );
++s1;
}
return( NULL );
}