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/* Optimized strlen implementation for PowerPC476.
Copyright (C) 2010-2021 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
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* strlen
Register Use
r3:source address and return length of string
r4:byte counter
Implementation description
Load 2 words at a time and count bytes, if we find null we subtract one from
the count and return the count value. We need to subtract one because
we don't count the null character as a byte. */
EALIGN (strlen,5,0)
neg r7,r3
clrlwi. r8,r7,29
addi r4,0,0
beq L(byte_count_loop)
mtctr r8
L(loop):
lbz r5,0(r3)
cmpi cr5,r5,0x0
addi r3,r3,0x1
addi r4,r4,0x1
beq cr5,L(end_strlen)
bdnz L(loop)
L(byte_count_loop):
lwz r5,0(r3)
lwz r6,4(r3)
dlmzb. r12,r5,r6
add r4,r4,r12
bne L(end_strlen)
lwz r5,8(r3)
lwz r6,12(r3)
dlmzb. r12,r5,r6
add r4,r4,r12
bne L(end_strlen)
lwz r5,16(r3)
lwz r6,20(r3)
dlmzb. r12,r5,r6
add r4,r4,r12
bne L(end_strlen)
lwz r5,24(r3)
lwz r6,28(r3)
addi r3,r3,0x20
dlmzb. r12,r5,r6
add r4,r4,r12
bne L(end_strlen)
b L(byte_count_loop)
L(end_strlen):
addi r3,r4,-1
blr
END (strlen)
libc_hidden_builtin_def (strlen)
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