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