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/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
.asciz "@(#)strstr.s 5.2 (Berkeley) 8/21/90"
#endif /* LIBC_SCCS and not lint */
/*
* Find the first occurrence of s2 as a substring in s1.
* If s2 is empty, return s1.
*
* char *strstr(s1, s2)
* const char *s1, *s2;
*/
#include "DEFS.h"
ENTRY(strstr, 0)
movq 4(ap),r3 /* r3 = s1, r4 = s2 */
movzwl $65535,r2 /* r2 = locc/matchc limit */
locc $0,r2,(r4) /* find '\0' in s2 */
beql 4f
subl3 r4,r1,r5 /* r5 = strlen(s2) */
beql 1f /* if r5 == 0, return s1 */
/*
* s2 is short enough to apply matchc.
* If s1 is long, we have to do it in stages.
*/
0: locc $0,r2,(r3) /* find '\0' in s1 */
beql 3f
/*
* Both strings are `short'; we can use matchc directly.
*/
subl3 r3,r1,r1 /* r1 = strlen(s1) */
matchc r5,(r4),r1,(r3) /* find substring */
bneq 2f
/*
* r3 points r5 bytes past match. Return the match.
*/
1: subl3 r5,r3,r0 /* return (byte_past_match - strlen(s2)) */
ret
/*
* There is no matching substring.
*/
2: clrl r0 /* return NULL */
ret
/*
* s1 is too long (> 65535 bytes) to apply matchc directly,
* but s2 is short enough. Apply s2 to s1, then (if not
* found yet) advancing s1 by (65536-strlen(s2)) bytes and
* loop.
*/
3: matchc r5,(r4),r2,(r3) /* search */
beql 1b /* if found, go return it */
decw r2 /* from 0 to 65535 */
incl r3 /* already advanced 65535, now 65536 */
subl2 r5,r3 /* ... minus strlen(s2) */
brb 0b
/*
* s2 is too long (> 65535 bytes) to bother with matchc.
*/
4: locc $0,r2,(r1) /* continue working on strlen(s2) */
beql 4b
subl3 r1,r4,r5 /* r5 = strlen(s2) */
movb (r4)+,r2 /* r2 = *s2++ */
decl r5 /* fix up length */
5: movb (r3)+,r0 /* r0 = *s1++ */
beql 2b /* if '\0', return NULL */
cmpb r0,r2
bneq 5b /* loop until first char found */
pushr R5|R4|R3|R2 /* save c, s1, s2, n */
pushr R5|R4|R3 /* strncmp(s1, s2, n) */
calls $3,_strncmp
popr R2|R3|R4|R5 /* restore */
tstl r0
bneq 5b /* loop until strncmp says rest same too */
subl3 $1,r3,r0 /* return previous s1 */
ret
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