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/* Optimized strcmp implementation for PowerPC.
Copyright (C) 1997, 1999 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <sysdep.h>
/* See strlen.s for comments on how the end-of-string testing works. */
EALIGN(strcmp,4,0)
/* int [r3] strcmp (const char *p1 [r3], const char *p2 [r4]) */
/* General register assignments:
r0: temporary
r3: pointer to previous word in s1
r4: pointer to previous word in s2
r5: current word from s1
r6: current word from s2
r7: 0xfefefeff
r8: 0x7f7f7f7f
r9: ~(word in s1 | 0x7f7f7f7f) */
/* Register assignments in the prologue:
r10: low 2 bits of p2-p1
r11: mask to orc with r5/r6 */
or r0,r4,r3
clrlwi. r0,r0,30
lis r7,0xfeff
bne L(unaligned)
lwz r5,0(r3)
lwz r6,0(r4)
lis r8,0x7f7f
addi r7,r7,-0x101
addi r8,r8,0x7f7f
b 1f
0: lwzu r5,4(r3)
bne cr1,L(different)
lwzu r6,4(r4)
1: add r0,r7,r5
nor r9,r8,r5
and. r0,r0,r9
cmpw cr1,r5,r6
beq+ 0b
L(endstring):
/* OK. We've hit the end of the string. We need to be careful that
we don't compare two strings as different because of gunk beyond
the end of the strings... */
and r0,r8,r5
beq cr1,L(equal)
add r0,r0,r8
xor. r10,r5,r6
andc r9,r9,r0
blt- L(highbit)
cntlzw r10,r10
cntlzw r9,r9
addi r9,r9,7
cmpw cr1,r9,r10
sub r3,r5,r6
bgelr+ cr1
L(equal):
li r3,0
blr
L(different):
lwz r5,-4(r3)
xor. r10,r5,r6
sub r3,r5,r6
bgelr+
L(highbit):
ori r3,r6,1
blr
/* Oh well. In this case, we just do a byte-by-byte comparison. */
.align 4
L(unaligned):
lbz r5,0(r3)
lbz r6,0(r4)
b 1f
0: lbzu r5,1(r3)
bne- 4f
lbzu r6,1(r4)
1: cmpwi cr1,r5,0
beq- cr1,3f
cmpw r5,r6
bne- 3f
lbzu r5,1(r3)
lbzu r6,1(r4)
cmpwi cr1,r5,0
cmpw r5,r6
bne+ cr1,0b
3: sub r3,r5,r6
blr
4: lbz r5,-1(r3)
sub r3,r5,r6
blr
END(strcmp)
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