10Sstevel@tonic-gate/* 20Sstevel@tonic-gate * CDDL HEADER START 30Sstevel@tonic-gate * 40Sstevel@tonic-gate * The contents of this file are subject to the terms of the 5*7298SMark.J.Nelson@Sun.COM * Common Development and Distribution License (the "License"). 6*7298SMark.J.Nelson@Sun.COM * You may not use this file except in compliance with the License. 70Sstevel@tonic-gate * 80Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 90Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 100Sstevel@tonic-gate * See the License for the specific language governing permissions 110Sstevel@tonic-gate * and limitations under the License. 120Sstevel@tonic-gate * 130Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 140Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 150Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 160Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 170Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 180Sstevel@tonic-gate * 190Sstevel@tonic-gate * CDDL HEADER END 200Sstevel@tonic-gate */ 210Sstevel@tonic-gate/* 220Sstevel@tonic-gate * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 230Sstevel@tonic-gate * Use is subject to license terms. 240Sstevel@tonic-gate */ 250Sstevel@tonic-gate 26*7298SMark.J.Nelson@Sun.COM .file "memcmp.s" 270Sstevel@tonic-gate 280Sstevel@tonic-gate/ 290Sstevel@tonic-gate/ memcmp(s1, s2, n) 300Sstevel@tonic-gate/ 310Sstevel@tonic-gate/ Compares n bytes: s1>s2: >0 s1==s2: 0 s1<s2: <0 320Sstevel@tonic-gate/ 330Sstevel@tonic-gate/ Fast assembly language version of the following C-program strcat 340Sstevel@tonic-gate/ which represents the `standard' for the C-library. 350Sstevel@tonic-gate/ 360Sstevel@tonic-gate/ int 370Sstevel@tonic-gate/ memcmp(const void *s1, const void *s2, size_t n) 380Sstevel@tonic-gate/ { 390Sstevel@tonic-gate/ if (s1 != s2 && n != 0) { 400Sstevel@tonic-gate/ const unsigned char *ps1 = s1; 410Sstevel@tonic-gate/ const unsigned char *ps2 = s2; 420Sstevel@tonic-gate/ 430Sstevel@tonic-gate/ do { 440Sstevel@tonic-gate/ if (*ps1++ != *ps2++) 450Sstevel@tonic-gate/ return (ps1[-1] - ps2[-1]); 460Sstevel@tonic-gate/ } while (--n != 0); 470Sstevel@tonic-gate/ } 480Sstevel@tonic-gate/ return (NULL); 490Sstevel@tonic-gate/ } 500Sstevel@tonic-gate/ 510Sstevel@tonic-gate/ This implementation conforms to SVID but does not implement 520Sstevel@tonic-gate/ the same algorithm as the portable version because it is 530Sstevel@tonic-gate/ inconvenient to get the difference of the differing characters. 540Sstevel@tonic-gate 550Sstevel@tonic-gate#include <sys/asm_linkage.h> 560Sstevel@tonic-gate 570Sstevel@tonic-gate ANSI_PRAGMA_WEAK(memcmp,function) 580Sstevel@tonic-gate 590Sstevel@tonic-gate#include "SYS.h" 600Sstevel@tonic-gate 610Sstevel@tonic-gate ENTRY(memcmp) 620Sstevel@tonic-gate pushl %edi / save register variable 630Sstevel@tonic-gate movl 8(%esp), %eax / %eax = address of string 1 640Sstevel@tonic-gate movl 12(%esp), %ecx / %ecx = address of string 2 650Sstevel@tonic-gate cmpl %eax, %ecx / if the same string 660Sstevel@tonic-gate je .equal / goto .equal 670Sstevel@tonic-gate movl 16(%esp), %edi / %edi = length in bytes 680Sstevel@tonic-gate cmpl $4, %edi / if %edi < 4 690Sstevel@tonic-gate jb .byte_check / goto .byte_check 700Sstevel@tonic-gate .align 4 710Sstevel@tonic-gate.word_loop: 720Sstevel@tonic-gate movl (%ecx), %edx / move 1 word from (%ecx) to %edx 730Sstevel@tonic-gate leal -4(%edi), %edi / %edi -= 4 740Sstevel@tonic-gate cmpl (%eax), %edx / compare 1 word from (%eax) with %edx 750Sstevel@tonic-gate jne .word_not_equal / if not equal, goto .word_not_equal 760Sstevel@tonic-gate leal 4(%ecx), %ecx / %ecx += 4 (next word) 770Sstevel@tonic-gate leal 4(%eax), %eax / %eax += 4 (next word) 780Sstevel@tonic-gate cmpl $4, %edi / if %edi >= 4 790Sstevel@tonic-gate jae .word_loop / goto .word_loop 800Sstevel@tonic-gate.byte_check: 810Sstevel@tonic-gate cmpl $0, %edi / if %edi == 0 820Sstevel@tonic-gate je .equal / goto .equal 830Sstevel@tonic-gate jmp .byte_loop / goto .byte_loop (checks in bytes) 840Sstevel@tonic-gate.word_not_equal: 850Sstevel@tonic-gate leal 4(%edi), %edi / %edi += 4 (post-decremented) 860Sstevel@tonic-gate .align 4 870Sstevel@tonic-gate.byte_loop: 880Sstevel@tonic-gate movb (%ecx), %dl / move 1 byte from (%ecx) to %dl 890Sstevel@tonic-gate cmpb %dl, (%eax) / compare %dl with 1 byte from (%eax) 900Sstevel@tonic-gate jne .not_equal / if not equal, goto .not_equal 910Sstevel@tonic-gate incl %ecx / %ecx++ (next byte) 920Sstevel@tonic-gate incl %eax / %eax++ (next byte) 930Sstevel@tonic-gate decl %edi / %edi-- 940Sstevel@tonic-gate jnz .byte_loop / if not zero, goto .byte_loop 950Sstevel@tonic-gate.equal: 960Sstevel@tonic-gate xorl %eax, %eax / %eax = 0 970Sstevel@tonic-gate popl %edi / restore register variable 980Sstevel@tonic-gate ret / return (NULL) 990Sstevel@tonic-gate .align 4 1000Sstevel@tonic-gate.not_equal: 1010Sstevel@tonic-gate sbbl %eax, %eax / %eax = 0 if no carry, %eax = -1 if carry 1020Sstevel@tonic-gate orl $1, %eax / %eax = 1 if no carry, %eax = -1 if carry 1030Sstevel@tonic-gate popl %edi / restore register variable 1040Sstevel@tonic-gate ret / return (NULL) 1050Sstevel@tonic-gate SET_SIZE(memcmp) 106