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