strchr_naive.S revision 1.3 
1/*-
2 * Copyright (c) 2013 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to The NetBSD Foundation
6 * by Matt Thomas of 3am Software Foundry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
19 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 * POSSIBILITY OF SUCH DAMAGE.
28 */
29#include <machine/asm.h>
30
31RCSID("$NetBSD: strchr_naive.S,v 1.3 2013/08/19 02:22:25 matt Exp $")
32
33/* LINTSTUB: char * strchr(const char *, int) */
34ENTRY(strchr)
35#ifdef __thumb__
36	movs	r3, #0xff
37	ands	r1, r1, r3	/* restrict to a byte value */
381:	ldrb	r3, [r0]	/* read a byte */
39	cmp	r3, r1		/* does it match? */
40	beq	2f		/*   yes, set return value */
41	adds	r0, r0, #1	/* advance to next byte */
42#ifdef _ARM_ARCH_T2
43	cbnz	r3, 1b		/* was it a NUL?  no, get next byte */
44#else
45	cmp	r3, #0		/* was it a NUL? */
46	bne	1b		/*   no, get next byte */
47#endif
48	movs	r0, #0		/* set return to NULL */
492:	RET			/* return */
50#else
51	mov	r2, r0		/* using r0 as return value */
52	mov	r0, #0		/* default to no match */
53	and	r1, r1, #0xff	/* restrict to a byte value */
541:	ldrb	r3, [r2], #1	/* read a byte */
55	cmp	r3, r1		/* does it match? */
56	subeq	r0, r2, #1	/*   yes, set return value to point to it */
57	cmpne	r3, #0		/*   no, was it a NUL? */
58	bne	1b		/*     no, get next byte */
59	RET
60#endif
61END(strchr)
62