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/*
* Copyright (c) 1988 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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 "@(#)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
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