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