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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 .file "strrchr.s" 27 28/ 29/ strrchr(sp, c) 30/ 31/ Returns the pointer in sp at which the character c last 32/ appears; NULL if no found 33/ 34/ Fast assembly language version of the following C-program strrchr 35/ which represents the `standard' for the C-library. 36/ 37/ char * 38/ strrchr(const char *sp, int c) 39/ { 40/ char *r = NULL; 41/ 42/ do { 43/ if (*sp == (char)c) 44/ r = (char *)sp; 45/ } while (*sp++); 46/ 47/ return (r); 48/ } 49/ 50 51#include "SYS.h" 52 53 ENTRY(strrchr) /* (char *s, int c) */ 54 movl $0, %eax / %rax = NULL (current occurrence) 55 movl %esi, %ecx / %cl == char to search for 56 testq $3, %rdi / if %rdi not word aligned 57 jnz .L1 / goto .L1 58 .align 4 59.L3: 60 movl (%rdi), %edx / move 1 word from (%rdi) to %edx 61 cmpb %cl, %dl / if the fist byte is not %cl 62 jne .L4 / goto .L4 63 movq %rdi, %rax / save this address to %rax 64.L4: 65 cmpb $0, %dl / if a null termination 66 je .L8 / goto .L8 67 68 cmpb %cl, %dh / if the second byte is not %cl 69 jne .L5 / goto .L5 70 leaq 1(%rdi), %rax / save this address to %rax 71.L5: 72 cmpb $0, %dh / if a null termination 73 je .L8 / goto .L8 74 75 shrl $16, %edx / right shift 16-bit 76 cmpb %cl, %dl / if the third byte is not %cl 77 jne .L6 / goto .L6 78 leaq 2(%rdi), %rax / save this address to %rax 79.L6: 80 cmpb $0, %dl / if a null termination 81 je .L8 / goto .L8 82 83 cmpb %cl, %dh / if the fourth byte is not %cl 84 jne .L7 / goto .L7 85 leaq 3(%rdi), %rax / save this address to %rax 86.L7: 87 cmpb $0, %dh / if a null termination 88 je .L8 / goto .L8 89 90 addq $4, %rdi / next word 91 jmp .L3 / goto .L3 92 .align 4 93.L1: 94 movb (%rdi), %dl / move 1 byte from (%rdi) to %dl 95 cmpb %cl, %dl / if %dl is not %cl 96 jne .L2 / goto .L2 97 movq %rdi, %rax / save this address to %rax 98.L2: 99 cmpb $0, %dl / if a null termination 100 je .L8 / goto .L8 101 102 incq %rdi / next byte 103 testq $3, %rdi / if %rdi not word aligned 104 jnz .L1 / goto .L1 105 jmp .L3 / goto .L3 (word aligned) 106 .align 4 107.L8: 108 ret / %rax points to the last occurrence or NULL 109 SET_SIZE(strrchr) 110