xref: /netbsd-src/lib/libc/arch/i386/string/rindex.S (revision ce0bb6e8d2e560ecacbe865a848624f94498063b)
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 without 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 *	$Id: rindex.S,v 1.7 1994/03/12 01:40:03 jtc Exp $
31 */
32
33#include <machine/asm.h>
34
35#if defined(LIBC_SCCS)
36	RCSID("$Id: rindex.S,v 1.7 1994/03/12 01:40:03 jtc Exp $")
37#endif
38
39/*
40 * strrchr(s, c)
41 * rindex(s, c)
42 *	return a pointer to the last occurance of the character c in
43 *	string s, or NULL if c does not occur in the string.
44 *
45 * %edx - pointer iterating through string
46 * %eax - pointer to last occurance of 'c'
47 * %cl  - character we're comparing against
48 * %bl  - character at %edx
49 *
50 * Written by:
51 *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
52 */
53
54#ifdef STRRCHR
55ENTRY(strrchr)
56#else
57ENTRY(rindex)
58#endif
59	pushl	%ebx
60	movl	8(%esp),%edx
61	movb	12(%esp),%cl
62	xorl	%eax,%eax		/* init pointer to null */
63	.align 2,0x90
64L1:
65	movb	(%edx),%bl
66	cmpb	%bl,%cl
67	jne	L2
68	movl	%edx,%eax
69L2:
70	incl	%edx
71	testb	%bl,%bl			/* null terminator??? */
72	jnz	L1
73	popl	%ebx
74	ret
75