strrchr_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: strrchr_naive.S,v 1.3 2013/08/19 02:36:27 matt Exp $") 32 33/* LINTSTUB: char * strrchr(const char *, int) */ 34ENTRY(strrchr) 35 mov r2, r0 /* using r0 as return value */ 36 movs r0, #0 /* default to no match */ 37#ifdef __thumb__ 38 movs r3, #0xff 39 ands r1, r1, r3 /* restrict to a byte value */ 401: ldrb r3, [r2] /* read a byte */ 41 cmp r3, r1 /* does it match? */ 42 bne 2f /* no, go and advance */ 43 mov r0, r2 /* yes, set return value to point to it */ 442: adds r2, r2, #1 /* advance to next byte */ 45#ifdef _ARM_ARCH_T2 46 cbnz r3, 1b /* was it a NUL? no, get next byte */ 47#else 48 cmp r3, #0 /* was it a NUL? */ 49 bne 1b /* no, get next byte */ 50#endif 51#else 52 and r1, r1, #0xff /* restrict to a byte value */ 531: ldrb r3, [r2], #1 /* read a byte */ 54 cmp r3, r1 /* does it match? */ 55 subeq r0, r2, #1 /* yes, set return value to point to it */ 56 cmp r3, #0 /* was it a NUL? */ 57 bne 1b /* no, get next byte */ 58#endif 59 RET 60END(strrchr) 61