mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
100 lines
2.6 KiB
ArmAsm
100 lines
2.6 KiB
ArmAsm
/* strchrnul - find a character or nul in a string
|
|
|
|
Copyright (C) 2014-2024 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>
|
|
|
|
/* Assumptions:
|
|
*
|
|
* ARMv8-a, AArch64, Advanced SIMD.
|
|
* MTE compatible.
|
|
*/
|
|
|
|
#define srcin x0
|
|
#define chrin w1
|
|
#define result x0
|
|
|
|
#define src x2
|
|
#define tmp1 x1
|
|
#define tmp2 x3
|
|
|
|
#define vrepchr v0
|
|
#define vdata v1
|
|
#define qdata q1
|
|
#define vhas_nul v2
|
|
#define vhas_chr v3
|
|
#define vend v4
|
|
#define dend d4
|
|
|
|
/*
|
|
Core algorithm:
|
|
For each 16-byte chunk we calculate a 64-bit nibble mask value with four bits
|
|
per byte. We take 4 bits of every comparison byte with shift right and narrow
|
|
by 4 instruction. Since the bits in the nibble mask reflect the order in
|
|
which things occur in the original string, counting leading zeros identifies
|
|
exactly which byte matched. */
|
|
|
|
ENTRY (__strchrnul)
|
|
PTR_ARG (0)
|
|
bic src, srcin, 15
|
|
dup vrepchr.16b, chrin
|
|
ld1 {vdata.16b}, [src]
|
|
cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
|
|
cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
|
|
lsl tmp2, srcin, 2
|
|
shrn vend.8b, vhas_chr.8h, 4 /* 128->64 */
|
|
fmov tmp1, dend
|
|
lsr tmp1, tmp1, tmp2 /* Mask padding bits. */
|
|
cbz tmp1, L(loop)
|
|
|
|
rbit tmp1, tmp1
|
|
clz tmp1, tmp1
|
|
add result, srcin, tmp1, lsr 2
|
|
ret
|
|
|
|
.p2align 4
|
|
L(loop):
|
|
ldr qdata, [src, 16]
|
|
cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
|
|
cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
|
|
umaxp vend.16b, vhas_chr.16b, vhas_chr.16b
|
|
fmov tmp1, dend
|
|
cbnz tmp1, L(end)
|
|
ldr qdata, [src, 32]!
|
|
cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
|
|
cmhs vhas_chr.16b, vhas_chr.16b, vdata.16b
|
|
umaxp vend.16b, vhas_chr.16b, vhas_chr.16b
|
|
fmov tmp1, dend
|
|
cbz tmp1, L(loop)
|
|
sub src, src, 16
|
|
L(end):
|
|
shrn vend.8b, vhas_chr.8h, 4 /* 128->64 */
|
|
add src, src, 16
|
|
fmov tmp1, dend
|
|
#ifndef __AARCH64EB__
|
|
rbit tmp1, tmp1
|
|
#endif
|
|
clz tmp1, tmp1
|
|
add result, src, tmp1, lsr 2
|
|
ret
|
|
|
|
END(__strchrnul)
|
|
libc_hidden_def (__strchrnul)
|
|
weak_alias (__strchrnul, strchrnul)
|