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strncmp.S revision 1.7
      1 /*
      2  * Copyright (c) 1993,94 Winning Strategies, Inc.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *      This product includes software developed by Winning Strategies, Inc.
     16  * 4. The name of the author may not be used to endorse or promote products
     17  *    derived from this software without specific prior written permission
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  *
     30  *	$Id: strncmp.S,v 1.7 1994/02/14 17:44:39 jtc Exp $
     31  */
     32 
     33 #if defined(LIBC_SCCS)
     34 	.text
     35 	.asciz "$Id: strncmp.S,v 1.7 1994/02/14 17:44:39 jtc Exp $"
     36 #endif
     37 
     38 #include <machine/asm.h>
     39 
     40 /*
     41  * strncmp(s1, s2, n)
     42  *	return an integer greater than, equal to, or less than 0,
     43  *	according as the first n characters of string s1 is greater
     44  *	than, equal to, or less than the string s2.
     45  *
     46  * %eax - pointer to s1
     47  * %ecx - pointer to s2
     48  * %edx - length
     49  *
     50  * Written by:
     51  *	J.T. Conklin (jtc (at) wimsey.com), Winning Strategies, Inc.
     52  */
     53 
     54 /*
     55  * I've unrolled the loop eight times: large enough to make a
     56  * significant difference, and small enough not to totally trash the
     57  * cache.
     58  */
     59 
     60 ENTRY(strncmp)
     61 	pushl	%ebx
     62 	movl	8(%esp),%eax
     63 	movl	12(%esp),%ecx
     64 	movl	16(%esp),%edx
     65 	testl	%edx,%edx
     66 	jmp	L2			/* Jump into the loop! */
     67 
     68 	.align 2,0x90
     69 L1:	incl	%eax
     70 	incl	%ecx
     71 	decl	%edx
     72 L2:	je	L4			/* strings are equal */
     73 	movb	(%eax),%bl
     74 	testb	%bl,%bl
     75 	je	L3
     76 	cmpb	%bl,(%ecx)
     77 	jne	L3
     78 
     79 	incl	%eax
     80 	incl	%ecx
     81 	decl	%edx
     82 	je	L4
     83 	movb	(%eax),%bl
     84 	testb	%bl,%bl
     85 	je	L3
     86 	cmpb	%bl,(%ecx)
     87 	jne	L3
     88 
     89 	incl	%eax
     90 	incl	%ecx
     91 	decl	%edx
     92 	je	L4
     93 	movb	(%eax),%bl
     94 	testb	%bl,%bl
     95 	je	L3
     96 	cmpb	%bl,(%ecx)
     97 	jne	L3
     98 
     99 	incl	%eax
    100 	incl	%ecx
    101 	decl	%edx
    102 	je	L4
    103 	movb	(%eax),%bl
    104 	testb	%bl,%bl
    105 	je	L3
    106 	cmpb	%bl,(%ecx)
    107 	jne	L3
    108 
    109 	incl	%eax
    110 	incl	%ecx
    111 	decl	%edx
    112 	je	L4
    113 	movb	(%eax),%bl
    114 	testb	%bl,%bl
    115 	je	L3
    116 	cmpb	%bl,(%ecx)
    117 	jne	L3
    118 
    119 	incl	%eax
    120 	incl	%ecx
    121 	decl	%edx
    122 	je	L4
    123 	movb	(%eax),%bl
    124 	testb	%bl,%bl
    125 	je	L3
    126 	cmpb	%bl,(%ecx)
    127 	jne	L3
    128 
    129 	incl	%eax
    130 	incl	%ecx
    131 	decl	%edx
    132 	je	L4
    133 	movb	(%eax),%bl
    134 	testb	%bl,%bl
    135 	je	L3
    136 	cmpb	%bl,(%ecx)
    137 	jne	L3
    138 
    139 	incl	%eax
    140 	incl	%ecx
    141 	decl	%edx
    142 	je	L4
    143 	movb	(%eax),%bl
    144 	testb	%bl,%bl
    145 	je	L3
    146 	cmpb	%bl,(%ecx)
    147 	je	L1
    148 
    149 	.align 2,0x90
    150 L3:	movzbl	(%eax),%eax		/* unsigned comparision */
    151 	movzbl	(%ecx),%ecx
    152 	subl	%ecx,%eax
    153 	popl	%ebx
    154 	ret
    155 	.align 2,0x90
    156 L4:	xorl	%eax,%eax
    157 	popl	%ebx
    158 	ret
    159