strrchr.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/strrchr.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 * strrchr(s, c)
40 *	return a pointer to the last occurance of the character c in
41 *	string s, or NULL if c does not occur in the string.
42 *
43 * %edx - pointer iterating through string
44 * %eax - pointer to last occurance of 'c'
45 * %cl  - character we're comparing against
46 * %bl  - character at %edx
47 *
48 * Written by:
49 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
50 */
51
52ENTRY(strrchr)
53	pushl	%ebx
54	movl	8(%esp),%edx
55	movb	12(%esp),%cl
56	xorl	%eax,%eax		/* init pointer to null */
57	.align 2,0x90
58L1:
59	movb	(%edx),%bl
60	cmpb	%bl,%cl
61	jne	L2
62	movl	%edx,%eax
63L2:
64	incl	%edx
65	testb	%bl,%bl			/* null terminator??? */
66	jne	L1
67	popl	%ebx
68	ret
69