/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
.file "strncmp.s"
#include "SYS.h"
ENTRY(strncmp)
pushl %esi / save register variables
movl 8(%esp),%esi / %esi = first string
movl %edi,%edx
movl 12(%esp),%edi / %edi = second string
cmpl %esi,%edi / same string?
je .equal
movl 16(%esp),%ecx / %ecx = length
incl %ecx / will later predecrement this uint
.loop:
decl %ecx
je .equal / Used all n chars?
movb (%esi),%al / slodb ; scab
cmpb (%edi),%al
jne .notequal_0 / Are the bytes equal?
testb %al,%al
je .equal / End of string?
decl %ecx
je .equal / Used all n chars?
movb 1(%esi),%al / slodb ; scab
cmpb 1(%edi),%al
jne .notequal_1 / Are the bytes equal?
testb %al,%al
je .equal / End of string?
decl %ecx
je .equal / Used all n chars?
movb 2(%esi),%al / slodb ; scab
cmpb 2(%edi),%al
jne .notequal_2 / Are the bytes equal?
testb %al,%al
je .equal / End of string?
decl %ecx
je .equal / Used all n chars?
movb 3(%esi),%al / slodb ; scab
cmpb 3(%edi),%al
jne .notequal_3 / Are the bytes equal?
addl $4,%esi
addl $4,%edi
testb %al,%al
jne .loop / End of string?
.equal:
popl %esi / restore registers
xorl %eax,%eax / return 0
movl %edx,%edi
ret
.align 4
.notequal_3:
incl %edi
.notequal_2:
incl %edi
.notequal_1:
incl %edi
.notequal_0:
popl %esi / restore registers
clc / clear carry bit
subb (%edi),%al
movl %edx,%edi
movl $-1, %eax / possibly wasted instr
jc .neg / did we overflow in the sub
movl $1, %eax / if not a > b
.neg:
ret
SET_SIZE(strncmp)