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/* Optimized strchr 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 this works. */
/* char * [r3] strchr (const char *s [r3] , int c [r4] )
r0: a temporary
r3: our return result.
r4: byte we're looking for, spread over the whole word
r5: the current word
r6: the constant 0xfefefeff (-0x01010101)
r7: the constant 0x7f7f7f7f
r8: pointer to the current word.
r9: a temporary
r10: the number of bits we should ignore in the first word
r11: a mask with the bits to ignore set to 0
r12: a temporary */
ENTRY(strchr)
rlwimi r4,r4,8,16,23
li r11,-1
rlwimi r4,r4,16,0,15
lis r6,0xfeff
lis r7,0x7f7f
clrrwi r8,r3,2
addi r7,r7,0x7f7f
addi r6,r6,0xfffffeff
rlwinm r10,r3,3,27,28
/* Test the first (partial?) word. */
lwz r5,0(r8)
srw r11,r11,r10
orc r5,r5,r11
add r0,r6,r5
nor r9,r7,r5
and. r0,r0,r9
xor r12,r4,r5
orc r12,r12,r11
b L(loopentry)
/* The loop. */
L(loop):lwzu r5,4(r8)
and. r0,r0,r9
/* Test for 0. */
add r0,r6,r5
nor r9,r7,r5
bne L(foundit)
and. r0,r0,r9
/* Start test for the bytes we're looking for. */
xor r12,r4,r5
L(loopentry):
add r0,r6,r12
nor r9,r7,r12
beq L(loop)
/* There is a zero byte in the word, but may also be a matching byte (either
before or after the zero byte). In fact, we may be looking for a
zero byte, in which case we return a match. We guess that this hasn't
happened, though. */
L(missed):
and. r0,r0,r9
li r3,0
beqlr
/* It did happen. Decide which one was first...
I'm not sure if this is actually faster than a sequence of
rotates, compares, and branches (we use it anyway because it's shorter). */
and r6,r7,r5
or r11,r7,r5
and r0,r7,r12
or r10,r7,r12
add r6,r6,r7
add r0,r0,r7
nor r5,r11,r6
nor r9,r10,r0
cmplw r5,r9
bgtlr
cntlzw r4,r9
srwi r4,r4,3
add r3,r8,r4
blr
L(foundit):
and r0,r7,r12
or r10,r7,r12
add r0,r0,r7
nor r9,r10,r0
cntlzw r4,r9
subi r8,r8,4
srwi r4,r4,3
add r3,r8,r4
blr
END(strchr)
weak_alias(strchr,index)
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