1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22/* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 .ident "%Z%%M% %I% %E% SMI" 28 29 .file "%M%" 30 31/ 32/ memchr(sptr, c1, n) 33/ 34/ Returns the pointer in sptr at which the character c1 appears; 35/ or NULL if not found in chars; doesn't stop at \0. 36/ 37/ Fast assembly language version of the following C-program memchr 38/ which represents the `standard' for the C-library. 39/ 40/ void * 41/ memchr(const void *sptr, int c1, size_t n) 42/ { 43/ if (n != 0) { 44/ unsigned char c = (unsigned char)c1; 45/ const unsigned char *sp = sptr; 46/ 47/ do { 48/ if (*sp++ == c) 49/ return ((void *)--sp); 50/ } while (--n != 0); 51/ } 52/ return (NULL); 53/ } 54/ 55 56#include "SYS.h" 57 58 .globl memchr 59 .align 4 60 61 ENTRY(memchr) /* (void *s, uchar_t c, size_t n) */ 62 movl %esi, %eax / move "c" to %eax 63 cmpq $4, %rdx / if number of bytes < 4 64 jb .L1 / goto .L1 65 testq $3, %rdi / if %rdi not word aligned 66 jnz .L2 / goto .L2 67 .align 4 68.L3: 69 movl (%rdi), %ecx / move 1 word from (%rdi) to %ecx 70 cmpb %cl, %al / if the first byte is %al 71 je .L4 / goto .L4 (found) 72 cmpb %ch, %al / if the second byte is %al 73 je .L5 / goto .L5 (found) 74 shrl $16, %ecx / right shift 16-bit 75 cmpb %cl, %al / if the third byte is %al 76 je .L6 / goto .L6 (found) 77 cmpb %ch, %al / if the fourth is %al 78 je .L7 / goto .L7 (found) 79 subq $4, %rdx / decrement number of bytes by 4 80 addq $4, %rdi / next word 81 cmpq $4, %rdx / if number of bytes >= 4 82 jae .L3 / goto .L3 83.L1: 84 cmpq $0, %rdx / if number of bytes == 0 85 jz .L8 / goto .L8 (not found) 86 cmpb (%rdi), %al / if a byte in (%rdi) is %al 87 je .L4 / goto .L4 (found) 88 decq %rdx / decrement number of bytes by 1 89 incq %rdi / next byte 90 jmp .L1 / goto .L1 91 .align 4 92.L8: 93 xorl %eax, %eax / not found 94 ret / return (0) 95 .align 4 96.L2: 97 cmpq $0, %rdx / if number of bytes == 0 98 jz .L8 / goto .L8 (not found) 99 cmpb (%rdi), %al / if a byte in (%rdi) is %al 100 je .L4 / goto .L4 (found) 101 incq %rdi / next byte 102 decq %rdx / decrement number of bytes by 1 103 testq $3, %rdi / if %rdi not word aligned 104 jnz .L2 / goto .L2 105 cmpq $4, %rdx / if number of bytes >= 4 106 jae .L3 / goto .L3 (word aligned) 107 jmp .L1 / goto .L1 108 .align 4 109.L7: 110 / found at the fourth byte 111 incq %rdi 112.L6: 113 / found at the third byte 114 incq %rdi 115.L5: 116 / found at the second byte 117 incq %rdi 118.L4: 119 / found at the first byte 120 movq %rdi,%rax 121 ret 122 SET_SIZE(memchr) 123