1/* 2 * Copyright (c) 1988 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 */ 17 18#if defined(LIBC_SCCS) && !defined(lint) 19 .asciz "@(#)strchr.s 5.3 (Berkeley) 06/01/90" 20#endif /* LIBC_SCCS and not lint */ 21 22/* 23 * Find the first occurence of c in the string cp. 24 * Return pointer to match or null pointer. 25 * 26 * char * 27 * strchr(cp, c) 28 * char *cp, c; 29 */ 30#include "DEFS.h" 31 32 .lcomm tbl,256 33 34ENTRY(strchr, 0) 35 movzwl $65535,r4 /* handy constant */ 36 movq 4(ap),r1 /* r1 = cp; r2 = c */ 37 movzbl r2,r2 38 beql Lzero /* special case for c == '\0' */ 39 40/* 41 * Fancy scanc version. Alas, it is not reentrant. 42 */ 43 movab tbl,r3 /* r3 = base of table */ 44 bbss $0,(r3),Lreent /* ensure not reentering */ 45 movab (r3)[r2],r5 46 incb (r5) /* mark both '\0' and c */ 470: 48 scanc r4,(r1),(r3),$1 /* look for c or '\0' */ 49 beql 0b /* still looking */ 50 movl r1,r0 /* return whatever we found */ 51 tstb (r0) 52 bneq 1f # unless it was '\0': 53 clrl r0 # then return NULL 541: 55 clrb (r5) /* clean up table */ 56 clrb (r3) 57 ret 58 59/* 60 * Special case for \0. 61 */ 62Lzero: 63 locc r2,r4,(r1) /* just find end of string */ 64 beql Lzero /* still looking */ 65 movl r1,r0 /* found it */ 66 ret 67 68/* 69 * Slower reentrant version is two two-step searches. The first 70 * phase runs until we know where the string ends; it locates the 71 * first occurrence of c within a 65535-byte block. If we find 72 * the end of the string first, we switch to the second phase, 73 * were we look only up to the known end of string. 74 */ 75Lreent: 760: /* first phase */ 77 movl r1,r3 78 locc $0,r4,(r3) /* look for '\0' */ 79 bneq 1f 80 locc r2,r4,(r3) /* look for c */ 81 beql 0b /* not found: reset pointer and loop */ 82 movl r1,r0 /* found: return it */ 83 ret 841: /* second phase */ 85 subl3 r3,r1,r0 /* length of short block */ 86 locc r2,r0,(r3) /* look for c */ 87 beql 2f /* not found: return NULL */ 88 movl r1,r0 892: ret 90