2016-11-04 22:37:10 +08:00
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/* memchr - find a character in a memory zone
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2021-01-03 03:32:25 +08:00
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Copyright (C) 2015-2021 Free Software Foundation, Inc.
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2016-11-04 22:37:10 +08:00
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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Prefer https to http for gnu.org and fsf.org URLs
Also, change sources.redhat.com to sourceware.org.
This patch was automatically generated by running the following shell
script, which uses GNU sed, and which avoids modifying files imported
from upstream:
sed -ri '
s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g
s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g
' \
$(find $(git ls-files) -prune -type f \
! -name '*.po' \
! -name 'ChangeLog*' \
! -path COPYING ! -path COPYING.LIB \
! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \
! -path manual/texinfo.tex ! -path scripts/config.guess \
! -path scripts/config.sub ! -path scripts/install-sh \
! -path scripts/mkinstalldirs ! -path scripts/move-if-change \
! -path INSTALL ! -path locale/programs/charmap-kw.h \
! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \
! '(' -name configure \
-execdir test -f configure.ac -o -f configure.in ';' ')' \
! '(' -name preconfigure \
-execdir test -f preconfigure.ac ';' ')' \
-print)
and then by running 'make dist-prepare' to regenerate files built
from the altered files, and then executing the following to cleanup:
chmod a+x sysdeps/unix/sysv/linux/riscv/configure
# Omit irrelevant whitespace and comment-only changes,
# perhaps from a slightly-different Autoconf version.
git checkout -f \
sysdeps/csky/configure \
sysdeps/hppa/configure \
sysdeps/riscv/configure \
sysdeps/unix/sysv/linux/csky/configure
# Omit changes that caused a pre-commit check to fail like this:
# remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines
git checkout -f \
sysdeps/powerpc/powerpc64/ppc-mcount.S \
sysdeps/unix/sysv/linux/s390/s390-64/syscall.S
# Omit change that caused a pre-commit check to fail like this:
# remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline
git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
2019-09-07 13:40:42 +08:00
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<https://www.gnu.org/licenses/>. */
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2016-11-04 22:37:10 +08:00
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#include <sysdep.h>
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/* Assumptions:
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*
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2020-06-10 00:06:03 +08:00
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* ARMv8-a, AArch64, Advanced SIMD.
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* MTE compatible.
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2016-11-04 22:37:10 +08:00
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*/
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2018-08-09 16:38:03 +08:00
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#ifndef MEMCHR
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# define MEMCHR __memchr
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#endif
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2016-11-04 22:37:10 +08:00
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/* Arguments and results. */
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#define srcin x0
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#define chrin w1
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#define cntin x2
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#define result x0
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#define src x3
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2020-06-10 00:06:03 +08:00
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#define cntrem x4
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#define synd x5
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#define shift x6
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#define tmp x7
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#define wtmp w7
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2016-11-04 22:37:10 +08:00
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#define vrepchr v0
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2020-06-10 00:06:03 +08:00
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#define qdata q1
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#define vdata v1
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#define vhas_chr v2
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#define vrepmask v3
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#define vend v4
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#define dend d4
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2016-11-04 22:37:10 +08:00
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/*
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2020-06-10 00:06:03 +08:00
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Core algorithm:
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For each 16-byte chunk we calculate a 64-bit syndrome value with four bits
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per byte. For even bytes, bits 0-3 are set if the relevant byte matched the
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requested character or the byte is NUL. Bits 4-7 must be zero. Bits 4-7 are
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set likewise for odd bytes so that adjacent bytes can be merged. Since the
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bits in the syndrome reflect the order in which things occur in the original
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string, counting trailing zeros identifies exactly which byte matched. */
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2016-11-04 22:37:10 +08:00
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2018-08-09 16:38:03 +08:00
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ENTRY (MEMCHR)
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2020-12-17 18:03:05 +08:00
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PTR_ARG (0)
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SIZE_ARG (2)
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2020-06-10 00:06:03 +08:00
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bic src, srcin, 15
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cbz cntin, L(nomatch)
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ld1 {vdata.16b}, [src]
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2016-11-04 22:37:10 +08:00
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dup vrepchr.16b, chrin
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2020-06-10 00:06:03 +08:00
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mov wtmp, 0xf00f
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dup vrepmask.8h, wtmp
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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lsl shift, srcin, 2
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and vhas_chr.16b, vhas_chr.16b, vrepmask.16b
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addp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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lsr synd, synd, shift
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cbz synd, L(start_loop)
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2016-11-04 22:37:10 +08:00
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2020-06-10 00:06:03 +08:00
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rbit synd, synd
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clz synd, synd
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add result, srcin, synd, lsr 2
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cmp cntin, synd, lsr 2
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csel result, result, xzr, hi
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ret
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L(start_loop):
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sub tmp, src, srcin
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add tmp, tmp, 16
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subs cntrem, cntin, tmp
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b.ls L(nomatch)
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/* Make sure that it won't overread by a 16-byte chunk */
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add tmp, cntrem, 15
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tbnz tmp, 4, L(loop32_2)
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.p2align 4
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L(loop32):
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ldr qdata, [src, 16]!
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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cbnz synd, L(end)
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L(loop32_2):
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ldr qdata, [src, 16]!
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subs cntrem, cntrem, 32
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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b.ls L(end)
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umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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cbz synd, L(loop32)
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2016-11-04 22:37:10 +08:00
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L(end):
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2020-06-10 00:06:03 +08:00
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and vhas_chr.16b, vhas_chr.16b, vrepmask.16b
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addp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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add tmp, srcin, cntin
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sub cntrem, tmp, src
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#ifndef __AARCH64EB__
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2016-11-04 22:37:10 +08:00
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rbit synd, synd
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2020-06-10 00:06:03 +08:00
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#endif
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2016-11-04 22:37:10 +08:00
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clz synd, synd
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2020-06-10 00:06:03 +08:00
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cmp cntrem, synd, lsr 2
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add result, src, synd, lsr 2
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csel result, result, xzr, hi
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2016-11-04 22:37:10 +08:00
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ret
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2020-06-10 00:06:03 +08:00
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L(nomatch):
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mov result, 0
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2016-11-04 22:37:10 +08:00
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ret
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2020-06-10 00:06:03 +08:00
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2018-08-09 16:38:03 +08:00
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END (MEMCHR)
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weak_alias (MEMCHR, memchr)
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2016-11-04 22:37:10 +08:00
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libc_hidden_builtin_def (memchr)
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