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: strlen_naive.S,v 1.9 2022/12/03 11:30:24 skrll Exp $")
32
33#ifdef STRNLEN
34/* LINTSTUB: size_t strnlen(const char *, size_t) */
35ENTRY(strnlen)
36	adds	r3, r0, #1	/* start of src + NUL */
37#ifdef __thumb__
38	adds	r2, r0, r1	/* &src[maxlen] */
39	mov	ip, r2
40#else
41	adds	ip, r0, r1	/* &src[maxlen] */
42#endif
431:	cmp	r0, ip		/* is this the end of string? */
44	beq	2f		/*   yes it is */
45#ifdef __thumb__
46	ldrb	r2, [r0]	/* read a byte */
47	adds	r0, r0, #1	/* advance to next byte */
48#else
49	ldrb	r2, [r0], #1	/* read a byte */
50#endif
51	cmp	r2, #0		/* is it a NUL? */
52	bne	1b		/*   no, get next byte */
53	subs	r0, r0, r3	/* get difference between start and end */
54	RET			/* return */
552:	mov	r0, r1		/* get maxlen */
56	RET			/* return */
57END(strnlen)
58#else /* STRNLEN */
59/* LINTSTUB: size_t strlen(const char *) */
60ENTRY(strlen)
61	adds	r3, r0, #1	/* start of src + NUL */
621:
63#ifdef __thumb__
64	ldrb	r2, [r0]	/* read a byte */
65	adds	r0, r0, #1
66#else
67	ldrb	r2, [r0], #1	/* read a byte */
68#endif
69	cmp	r2, #0		/* is it a NUL? */
70	bne	1b		/*   no, get next byte */
71	subs	r0, r0, r3	/* return difference between start and end */
72	RET
73END(strlen)
74#endif /* !STRNLEN */
75