/* * Copyright (c) 1988 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that: (1) source distributions retain this entire copyright * notice and comment, and (2) distributions including binaries display * the following acknowledgement: ``This product includes software * developed by the University of California, Berkeley and its contributors'' * in the documentation or other materials provided with the distribution * and in all advertising materials mentioning features or use of this * software. 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #if defined(LIBC_SCCS) && !defined(lint) .asciz "@(#)strchr.s 5.4 (Berkeley) 6/1/90" #endif /* LIBC_SCCS and not lint */ /* * Find the first occurence of c in the string cp. * Return pointer to match or null pointer. * * char * * strchr(cp, c) * char *cp, c; */ #include "DEFS.h" .lcomm tbl,256 ENTRY(strchr, 0) movzwl $65535,r4 /* handy constant */ movq 4(ap),r1 /* r1 = cp; r2 = c */ movzbl r2,r2 beql Lzero /* special case for c == '\0' */ /* * Fancy scanc version. Alas, it is not reentrant. */ movab tbl,r3 /* r3 = base of table */ bbss $0,(r3),Lreent /* ensure not reentering */ movab (r3)[r2],r5 incb (r5) /* mark both '\0' and c */ 0: scanc r4,(r1),(r3),$1 /* look for c or '\0' */ beql 0b /* still looking */ movl r1,r0 /* return whatever we found */ tstb (r0) bneq 1f # unless it was '\0': clrl r0 # then return NULL 1: clrb (r5) /* clean up table */ clrb (r3) ret /* * Special case for \0. */ Lzero: locc r2,r4,(r1) /* just find end of string */ beql Lzero /* still looking */ movl r1,r0 /* found it */ ret /* * Slower reentrant version is two two-step searches. The first * phase runs until we know where the string ends; it locates the * first occurrence of c within a 65535-byte block. If we find * the end of the string first, we switch to the second phase, * were we look only up to the known end of string. */ Lreent: 0: /* first phase */ movl r1,r3 locc $0,r4,(r3) /* look for '\0' */ bneq 1f locc r2,r4,(r3) /* look for c */ beql 0b /* not found: reset pointer and loop */ movl r1,r0 /* found: return it */ ret 1: /* second phase */ subl3 r3,r1,r0 /* length of short block */ locc r2,r0,(r3) /* look for c */ beql 2f /* not found: return NULL */ movl r1,r0 2: ret