memchr.S revision 85437 
1/*
2 * Copyright (c) 1993 Winning Strategies, Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *      This product includes software developed by Winning Strategies, Inc.
16 * 4. The name of the author may not be used to endorse or promote products
17 *    derived from this software withough specific prior written permission
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#if defined(LIBC_RCS) && !defined(lint)
32	.text
33        .asciz "$FreeBSD: head/lib/libc/i386/string/memchr.S 85437 2001-10-24 20:29:14Z peter $"
34#endif /* LIBC_RCS and not lint */
35
36#include <machine/asm.h>
37
38/*
39 * memchr (b, c, len)
40 *	locates the first occurance of c in string b.
41 *
42 * Written by:
43 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
44 */
45
46ENTRY(memchr)
47	pushl	%edi
48	movl	8(%esp),%edi		/* string address */
49	movl	12(%esp),%eax		/* set character to search for */
50	movl	16(%esp),%ecx		/* set length of search */
51	testl	%esp,%esp		/* clear Z flag, for len == 0 */
52	cld				/* set search forward */
53	repne				/* search! */
54	scasb
55	jnz	L1			/* scan failed, return null */
56	leal	-1(%edi),%eax		/* adjust result of scan */
57	popl	%edi
58	ret
59	.align 2,0x90
60L1:	xorl	%eax,%eax
61	popl	%edi
62	ret
63