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/* Optimized strncmp implementation for PowerPC476.
Copyright (C) 2010 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <bp-sym.h>
#include <bp-asm.h>
/* strncmp
Register Use
r0:temp return equality
r3:source1 address, return equality
r4:source2 address
r5:byte count
Implementation description
Touch in 3 lines of D-cache.
If source1 or source2 is unaligned copy 0-3 bytes to make source1 aligned
Check 2 words from src1 and src2. If unequal jump to end and
return src1 > src2 or src1 < src2.
If null check bytes before null and then jump to end and
return src1 > src2, src1 < src2 or src1 = src2.
If count = zero check bytes before zero counter and then jump to end and
return src1 > src2, src1 < src2 or src1 = src2.
If src1 = src2 and no null, repeat. */
EALIGN (BP_SYM(strncmp),5,0)
neg r7,r3
clrlwi r7,r7,20
neg r8,r4
clrlwi r8,r8,20
srwi. r7,r7,3
beq L(prebyte_count_loop)
srwi. r8,r8,3
beq L(prebyte_count_loop)
cmplw r7,r8
mtctr r7
ble L(preword2_count_loop)
mtctr r8
L(preword2_count_loop):
srwi. r6,r5,3
beq L(prebyte_count_loop)
mfctr r7
cmplw r6,r7
bgt L(set_count_loop)
mtctr r6
clrlwi r5,r5,29
L(word2_count_loop):
lwz r10,0(r3)
lwz r6,4(r3)
addi r3,r3,0x08
lwz r8,0(r4)
lwz r9,4(r4)
addi r4,r4,0x08
dlmzb. r12,r10,r6
bne L(end_check)
cmplw r10,r8
bne L(st1)
cmplw r6,r9
bne L(st1)
bdnz L(word2_count_loop)
L(prebyte_count_loop):
addi r5,r5,1
mtctr r5
bdz L(end_strncmp)
L(byte_count_loop):
lbz r6,0(r3)
addi r3,r3,1
lbz r7,0(r4)
addi r4,r4,1
cmplw r6,r7
bne L(st1)
cmpwi r6,0
beq L(end_strncmp)
bdnz L(byte_count_loop)
b L(end_strncmp)
L(set_count_loop):
slwi r7,r7,3
subf r5,r7,r5
b L(word2_count_loop)
L(end_check):
subfic r12,r12,4
blt L(end_check2)
rlwinm r12,r12,3,0,31
srw r10,r10,r12
srw r8,r8,r12
cmplw r10,r8
bne L(st1)
b L(end_strncmp)
L(end_check2):
addi r12,r12,4
cmplw r10,r8
rlwinm r12,r12,3,0,31
bne L(st1)
srw r6,r6,r12
srw r9,r9,r12
cmplw r6,r9
bne L(st1)
L(end_strncmp):
addi r3,r0,0
blr
L(st1):
mfcr r3
blr
END (BP_SYM (strncmp))
libc_hidden_builtin_def (strncmp)
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