strchr_naive.S revision 1.3
11.1Smatt/*- 21.1Smatt * Copyright (c) 2013 The NetBSD Foundation, Inc. 31.1Smatt * All rights reserved. 41.1Smatt * 51.1Smatt * This code is derived from software contributed to The NetBSD Foundation 61.1Smatt * by Matt Thomas of 3am Software Foundry. 71.1Smatt * 81.1Smatt * Redistribution and use in source and binary forms, with or without 91.1Smatt * modification, are permitted provided that the following conditions 101.1Smatt * are met: 111.1Smatt * 1. Redistributions of source code must retain the above copyright 121.1Smatt * notice, this list of conditions and the following disclaimer. 131.1Smatt * 2. Redistributions in binary form must reproduce the above copyright 141.1Smatt * notice, this list of conditions and the following disclaimer in the 151.1Smatt * documentation and/or other materials provided with the distribution. 161.1Smatt * 171.1Smatt * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 181.1Smatt * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 191.1Smatt * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 201.1Smatt * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 211.1Smatt * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 221.1Smatt * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 231.1Smatt * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 241.1Smatt * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 251.1Smatt * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 261.1Smatt * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 271.1Smatt * POSSIBILITY OF SUCH DAMAGE. 281.1Smatt */ 291.1Smatt#include <machine/asm.h> 301.1Smatt 311.3SmattRCSID("$NetBSD: strchr_naive.S,v 1.3 2013/08/19 02:22:25 matt Exp $") 321.1Smatt 331.1Smatt/* LINTSTUB: char * strchr(const char *, int) */ 341.1SmattENTRY(strchr) 351.3Smatt#ifdef __thumb__ 361.3Smatt movs r3, #0xff 371.3Smatt ands r1, r1, r3 /* restrict to a byte value */ 381.3Smatt1: ldrb r3, [r0] /* read a byte */ 391.3Smatt cmp r3, r1 /* does it match? */ 401.3Smatt beq 2f /* yes, set return value */ 411.3Smatt adds r0, r0, #1 /* advance to next byte */ 421.3Smatt#ifdef _ARM_ARCH_T2 431.3Smatt cbnz r3, 1b /* was it a NUL? no, get next byte */ 441.3Smatt#else 451.3Smatt cmp r3, #0 /* was it a NUL? */ 461.3Smatt bne 1b /* no, get next byte */ 471.3Smatt#endif 481.3Smatt movs r0, #0 /* set return to NULL */ 491.3Smatt2: RET /* return */ 501.3Smatt#else 511.2Smatt mov r2, r0 /* using r0 as return value */ 521.1Smatt mov r0, #0 /* default to no match */ 531.1Smatt and r1, r1, #0xff /* restrict to a byte value */ 541.2Smatt1: ldrb r3, [r2], #1 /* read a byte */ 551.1Smatt cmp r3, r1 /* does it match? */ 561.2Smatt subeq r0, r2, #1 /* yes, set return value to point to it */ 571.2Smatt cmpne r3, #0 /* no, was it a NUL? */ 581.1Smatt bne 1b /* no, get next byte */ 591.1Smatt RET 601.3Smatt#endif 611.1SmattEND(strchr) 62