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) 54 pushl %edi / save register variable 55 movl 8(%esp), %eax / %eax = string address 56 movb 12(%esp), %cl / %cl = char sought 57 movl $0, %edi / %edi = NULL (current occurrence) 58 59 testl $3, %eax / if %eax not word aligned 60 jnz .L1 / goto .L1 61 .align 4 62.L3: 63 movl (%eax), %edx / move 1 word from (%eax) to %edx 64 cmpb %cl, %dl / if the fist byte is not %cl 65 jne .L4 / goto .L4 66 movl %eax, %edi / save this address to %edi 67.L4: 68 cmpb $0, %dl / if a null termination 69 je .L8 / goto .L8 70 71 cmpb %cl, %dh / if the second byte is not %cl 72 jne .L5 / goto .L5 73 leal 1(%eax), %edi / save this address to %edi 74.L5: 75 cmpb $0, %dh / if a null termination 76 je .L8 / goto .L8 77 78 shrl $16, %edx / right shift 16-bit 79 cmpb %cl, %dl / if the third byte is not %cl 80 jne .L6 / goto .L6 81 leal 2(%eax), %edi / save this address to %edi 82.L6: 83 cmpb $0, %dl / if a null termination 84 je .L8 / goto .L8 85 86 cmpb %cl, %dh / if the fourth byte is not %cl 87 jne .L7 / goto .L7 88 leal 3(%eax), %edi / save this address to %edi 89.L7: 90 cmpb $0, %dh / if a null termination 91 je .L8 / goto .L8 92 93 addl $4, %eax / next word 94 jmp .L3 / goto .L3 95 .align 4 96.L1: 97 movb (%eax), %dl / move 1 byte from (%eax) to %dl 98 cmpb %cl, %dl / if %dl is not %cl 99 jne .L2 / goto .L2 100 movl %eax, %edi / save this address to %edi 101.L2: 102 cmpb $0, %dl / if a null termination 103 je .L8 / goto .L8 104 105 incl %eax / next byte 106 testl $3, %eax / if %eax not word aligned 107 jnz .L1 / goto .L1 108 jmp .L3 / goto .L3 (word aligned) 109 .align 4 110.L8: 111 movl %edi, %eax / %edi points to the last occurrence or NULL 112 popl %edi / restore register variable 113 ret 114 SET_SIZE(strrchr) 115