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/* Optimized strchr implementation using basic LoongArch instructions.
Copyright (C) 2023 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>
#include <sys/regdef.h>
#include <sys/asm.h>
#if IS_IN (libc)
# define STRCHR_NAME __strchr_aligned
#else
# define STRCHR_NAME strchr
#endif
LEAF(STRCHR_NAME, 6)
slli.d t1, a0, 3
bstrins.d a0, zero, 2, 0
lu12i.w a2, 0x01010
ld.d t2, a0, 0
ori a2, a2, 0x101
andi a1, a1, 0xff
bstrins.d a2, a2, 63, 32
li.w t0, -1
mul.d a1, a1, a2
sll.d t0, t0, t1
slli.d a3, a2, 7
orn t2, t2, t0
sll.d t3, a1, t1
xor t4, t2, t3
sub.d a4, t2, a2
sub.d a5, t4, a2
andn a4, a4, t2
andn a5, a5, t4
or t0, a4, a5
and t0, t0, a3
bnez t0, L(end)
addi.d a0, a0, 8
L(loop):
ld.d t4, a0, 0
xor t2, t4, a1
sub.d a4, t4, a2
sub.d a5, t2, a2
andn a4, a4, t4
andn a5, a5, t2
or t0, a4, a5
and t0, t0, a3
bnez t0, L(end)
ld.d t4, a0, 8
addi.d a0, a0, 16
xor t2, t4, a1
sub.d a4, t4, a2
sub.d a5, t2, a2
andn a4, a4, t4
andn a5, a5, t2
or t0, a4, a5
and t0, t0, a3
beqz t0, L(loop)
addi.d a0, a0, -8
L(end):
and t0, a5, a3
and t1, a4, a3
ctz.d t0, t0
ctz.d t1, t1
srli.w t2, t0, 3
sltu t3, t1, t0
add.d a0, a0, t2
masknez a0, a0, t3
jr ra
END(STRCHR_NAME)
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