glibc/sysdeps/arm/armv6/rawmemchr.S
Paul Eggert 5a82c74822 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 02:43:31 -07:00

106 lines
3.1 KiB
ArmAsm

/* rawmemchr -- find a byte within an unsized memory block.
Copyright (C) 2013-2019 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>
.syntax unified
.text
ENTRY (__rawmemchr)
@ r0 = start of string
@ r1 = character to match
@ returns a pointer to the match, which must be present.
ldrb r2, [r0] @ load first byte asap
@ To cater to long strings, we want to search through a few
@ characters until we reach an aligned pointer. To cater to
@ small strings, we don't want to start doing word operations
@ immediately. The compromise is a maximum of 16 bytes less
@ whatever is required to end with an aligned pointer.
@ r3 = number of characters to search in alignment loop
and r3, r0, #7
uxtb r1, r1
rsb r3, r3, #15 @ 16 - 1 peeled loop iteration
cmp r2, r1
it eq
bxeq lr
@ Loop until we find ...
1: ldrb r2, [r0, #1]!
subs r3, r3, #1 @ ... the alignment point
it ne
cmpne r2, r1 @ ... or C
bne 1b
@ Disambiguate the exit possibilites above
cmp r2, r1 @ Found C
it eq
bxeq lr
add r0, r0, #1
@ So now we're aligned.
ldrd r2, r3, [r0], #8
orr r1, r1, r1, lsl #8 @ Replicate C to all bytes
#ifdef ARCH_HAS_T2
movw ip, #0x0101
pld [r0, #64]
movt ip, #0x0101
#else
ldr ip, =0x01010101
pld [r0, #64]
#endif
orr r1, r1, r1, lsl #16
@ Loop searching for C, 8 bytes at a time.
@ Subtracting (unsigned saturating) from 1 means result of 1 for
@ any byte that was originally zero and 0 otherwise. Therefore
@ we consider the lsb of each byte the "found" bit.
2: eor r2, r2, r1 @ Convert C bytes to 0
eor r3, r3, r1
uqsub8 r2, ip, r2 @ Find C
uqsub8 r3, ip, r3
pld [r0, #128]
orrs r3, r3, r2 @ Test both words for found
it eq
ldrdeq r2, r3, [r0], #8
beq 2b
@ Found something. Disambiguate between first and second words.
@ Adjust r0 to point to the word containing the match.
@ Adjust r2 to the found bits for the word containing the match.
cmp r2, #0
sub r0, r0, #4
ite eq
moveq r2, r3
subne r0, r0, #4
@ Find the bit-offset of the match within the word. Note that the
@ bit result from clz will be 7 higher than "true", but we'll
@ immediately discard those bits converting to a byte offset.
#ifdef __ARMEL__
rev r2, r2 @ For LE, count from the little end
#endif
clz r2, r2
add r0, r0, r2, lsr #3 @ Adjust the pointer to the found byte
bx lr
END (__rawmemchr)
weak_alias (__rawmemchr, rawmemchr)
libc_hidden_def (__rawmemchr)