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/*
* Copyright (c) 1993,94 Winning Strategies, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Winning Strategies, Inc.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: strncmp.S,v 1.2 1994/12/27 13:12:34 bde Exp $
*/
#if defined(LIBC_RCS) && !defined(lint)
.text
.asciz "$Id: strncmp.S,v 1.2 1994/12/27 13:12:34 bde Exp $"
#endif /* LIBC_RCS and not lint */
#include "DEFS.h"
/*
* strncmp(s1, s2, n)
* return an integer greater than, equal to, or less than 0,
* according as the first n characters of string s1 is greater
* than, equal to, or less than the string s2.
*
* %eax - pointer to s1
* %ecx - pointer to s2
* %edx - length
*
* Written by:
* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
*/
/*
* I've unrolled the loop eight times: large enough to make a
* significant difference, and small enough not to totally trash the
* cache.
*
* TODO: change all the jz's back to je for consistency.
*/
ENTRY(strncmp)
pushl %ebx
movl 8(%esp),%eax
movl 12(%esp),%ecx
movl 16(%esp),%edx
testl %edx,%edx
jmp L2 /* Jump into the loop! */
.align 2,0x90
L1: incl %eax
incl %ecx
decl %edx
L2: jz L4 /* strings are equal */
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
/*
* XXX it might be best to move the next 4 instructions to the end of the
* unrolled part of the loop. The unrolled part would then be
* movb n(%eax),%bl; testb %bl, %bl; je L3; cmpb n(%ecx); jne L3
* or maybe better
* movb n(%eax),%bl; cmpb n(%ecx); jne L3; testb %bl,%bl; je return_0
* for n = 0, 1, ..., 8. The end of the loop would be
* L1: addl $8,%eax; addl $8,%ecx; subl $8,%edx; cmpl $8,%edx; jae Lx
* where residual counts of 0 to 7 are handled at Lx. However, this would
* be slower for short strings. Cache effects are probably not so
* important because we are only handling a byte at a time.
*/
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
jne L3
incl %eax
incl %ecx
decl %edx
jz L4
movb (%eax),%bl
testb %bl,%bl
jz L3
cmpb %bl,(%ecx)
je L1
.align 2,0x90
L3: movzbl (%eax),%eax /* unsigned comparison */
movzbl (%ecx),%ecx
subl %ecx,%eax
popl %ebx
ret
.align 2,0x90
L4: xorl %eax,%eax
popl %ebx
ret
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