142084Sbostic/*- 2*61222Sbostic * Copyright (c) 1990, 1993 3*61222Sbostic * The Regents of the University of California. All rights reserved. 442084Sbostic * 542084Sbostic * %sccs.include.redist.c% 642084Sbostic */ 742084Sbostic 842084Sbostic#if defined(LIBC_SCCS) && !defined(lint) 9*61222Sbostic .asciz "@(#)strstr.s 8.1 (Berkeley) 06/04/93" 1042084Sbostic#endif /* LIBC_SCCS and not lint */ 1142084Sbostic 1242084Sbostic/* 1342084Sbostic * Find the first occurrence of s2 as a substring in s1. 1442084Sbostic * If s2 is empty, return s1. 1542084Sbostic * 1642084Sbostic * char *strstr(s1, s2) 1742084Sbostic * const char *s1, *s2; 1842084Sbostic */ 1942084Sbostic#include "DEFS.h" 2042084Sbostic 2142084SbosticENTRY(strstr, 0) 2242084Sbostic movq 4(ap),r3 /* r3 = s1, r4 = s2 */ 2342084Sbostic movzwl $65535,r2 /* r2 = locc/matchc limit */ 2442084Sbostic locc $0,r2,(r4) /* find '\0' in s2 */ 2542084Sbostic beql 4f 2645053Sbostic subl3 r4,r1,r5 /* r5 = strlen(s2) */ 2742084Sbostic beql 1f /* if r5 == 0, return s1 */ 2842084Sbostic 2942084Sbostic /* 3042084Sbostic * s2 is short enough to apply matchc. 3142084Sbostic * If s1 is long, we have to do it in stages. 3242084Sbostic */ 3342084Sbostic0: locc $0,r2,(r3) /* find '\0' in s1 */ 3442084Sbostic beql 3f 3542084Sbostic 3642084Sbostic /* 3742084Sbostic * Both strings are `short'; we can use matchc directly. 3842084Sbostic */ 3945053Sbostic subl3 r3,r1,r1 /* r1 = strlen(s1) */ 4042084Sbostic matchc r5,(r4),r1,(r3) /* find substring */ 4142084Sbostic bneq 2f 4242084Sbostic 4342084Sbostic /* 4442084Sbostic * r3 points r5 bytes past match. Return the match. 4542084Sbostic */ 4642084Sbostic1: subl3 r5,r3,r0 /* return (byte_past_match - strlen(s2)) */ 4742084Sbostic ret 4842084Sbostic 4942084Sbostic /* 5042084Sbostic * There is no matching substring. 5142084Sbostic */ 5242084Sbostic2: clrl r0 /* return NULL */ 5342084Sbostic ret 5442084Sbostic 5542084Sbostic /* 5642084Sbostic * s1 is too long (> 65535 bytes) to apply matchc directly, 5742084Sbostic * but s2 is short enough. Apply s2 to s1, then (if not 5842084Sbostic * found yet) advancing s1 by (65536-strlen(s2)) bytes and 5942084Sbostic * loop. 6042084Sbostic */ 6142084Sbostic3: matchc r5,(r4),r2,(r3) /* search */ 6242084Sbostic beql 1b /* if found, go return it */ 6342084Sbostic decw r2 /* from 0 to 65535 */ 6442084Sbostic incl r3 /* already advanced 65535, now 65536 */ 6542084Sbostic subl2 r5,r3 /* ... minus strlen(s2) */ 6642084Sbostic brb 0b 6742084Sbostic 6842084Sbostic /* 6942084Sbostic * s2 is too long (> 65535 bytes) to bother with matchc. 7042084Sbostic */ 7142084Sbostic4: locc $0,r2,(r1) /* continue working on strlen(s2) */ 7242084Sbostic beql 4b 7342084Sbostic subl3 r1,r4,r5 /* r5 = strlen(s2) */ 7442084Sbostic movb (r4)+,r2 /* r2 = *s2++ */ 7542084Sbostic decl r5 /* fix up length */ 7642084Sbostic5: movb (r3)+,r0 /* r0 = *s1++ */ 7742084Sbostic beql 2b /* if '\0', return NULL */ 7842084Sbostic cmpb r0,r2 7942084Sbostic bneq 5b /* loop until first char found */ 8042084Sbostic pushr R5|R4|R3|R2 /* save c, s1, s2, n */ 8142084Sbostic pushr R5|R4|R3 /* strncmp(s1, s2, n) */ 8242084Sbostic calls $3,_strncmp 8342084Sbostic popr R2|R3|R4|R5 /* restore */ 8442084Sbostic tstl r0 8542084Sbostic bneq 5b /* loop until strncmp says rest same too */ 8642084Sbostic subl3 $1,r3,r0 /* return previous s1 */ 8742084Sbostic ret 88