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author | Joseph Myers <joseph@codesourcery.com> | 2014-02-08 01:49:39 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2014-02-08 01:49:39 +0000 |
commit | c6bfe5c4d756913297db03f55e42016d1c48918c (patch) | |
tree | 898d2910ef903f46b596ad54e519ed4495357766 /sysdeps/arm/armv6/strchr.S | |
parent | 852fa2dd3aa1a687780e27300df9eb0bdc433863 (diff) | |
download | glibc-c6bfe5c4d756913297db03f55e42016d1c48918c.tar.gz |
Move arm from ports to libc.
I've moved the ARM port from ports to the main sysdeps hierarchy.
Beyond the README update, the move of the files was simply
git mv ports/sysdeps/arm sysdeps/arm
git mv ports/sysdeps/unix/arm sysdeps/unix/arm
git mv ports/sysdeps/unix/sysv/linux/arm sysdeps/unix/sysv/linux/arm
and in addition to the ChangeLog entries here, I put a note at the top
of ports/ChangeLog.arm similar to that at the top of
ChangeLog.powerpc. There is deliberately no NEWS change, as I think
it makes the most sense to put in a general note above all ports
having moved if we can achieve that for 2.20.
Tested that disassembly of installed shared libraries for arm is the
same before and after this patch, except for data (not instructions)
in ld.so (there are assertions in sysdeps/arm/dl-machine.h, and the
path by which that file is found, and so by which it appears in the
assertion message, changes as a result of the move).
* sysdeps/arm: Move directory from ports/sysdeps/arm.
* sysdeps/unix/arm: Move directory from ports/sysdeps/unix/arm.
* sysdeps/unix/sysv/linux/arm: Move directory from
ports/sysdeps/unix/sysv/linux/arm.
* README: Update listing for arm-*-linux-gnueabi.
ports/ChangeLog.arm:
* sysdeps/arm: Move directory to ../sysdeps/arm.
* sysdeps/unix/arm: Move directory to ../sysdeps.arm.
* sysdeps/unix/sysv/linux/arm: Move directory to
../sysdeps/unix/sysv/linux/arm.
Diffstat (limited to 'sysdeps/arm/armv6/strchr.S')
-rw-r--r-- | sysdeps/arm/armv6/strchr.S | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/sysdeps/arm/armv6/strchr.S b/sysdeps/arm/armv6/strchr.S new file mode 100644 index 0000000000..e4de0f3323 --- /dev/null +++ b/sysdeps/arm/armv6/strchr.S @@ -0,0 +1,147 @@ +/* strchr -- find the first instance of C in a nul-terminated string. + Copyright (C) 2013-2014 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 + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + + .syntax unified + .text + +ENTRY (strchr) + @ r0 = start of string + @ r1 = character to match + @ returns NULL for no match, or a pointer to the match + sfi_breg r0, \ + ldrb r2, [\B] @ load the first byte asap + uxtb r1, r1 + + @ 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 + rsb r3, r3, #15 @ 16 - 1 peeled loop iteration + cmp r2, r1 @ Found C? + it ne + cmpne r2, #0 @ Found EOS? + beq 99f + + @ Loop until we find ... +1: sfi_breg r0, \ + ldrb r2, [\B, #1]! + subs r3, r3, #1 @ ... the aligment point + it ne + cmpne r2, r1 @ ... or the character + it ne + cmpne r2, #0 @ ... or EOS + bne 1b + + @ Disambiguate the exit possibilites above + cmp r2, r1 @ Found the character + it ne + cmpne r2, #0 @ Found EOS + beq 99f + add r0, r0, #1 + + @ So now we're aligned. Now we actually need a stack frame. + push { r4, r5, r6, r7 } + cfi_adjust_cfa_offset (16) + cfi_rel_offset (r4, 0) + cfi_rel_offset (r5, 4) + cfi_rel_offset (r6, 8) + cfi_rel_offset (r7, 12) + + sfi_breg r0, \ + ldrd r2, r3, [\B], #8 + orr r1, r1, r1, lsl #8 @ Replicate C to all bytes +#ifdef ARCH_HAS_T2 + movw ip, #0x0101 + sfi_pld r0, #64 + movt ip, #0x0101 +#else + ldr ip, =0x01010101 + sfi_pld r0, #64 +#endif + orr r1, r1, r1, lsl #16 + + @ Loop searching for EOS or C, 8 bytes at a time. +2: + @ 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. + uqsub8 r4, ip, r2 @ Find EOS + eor r6, r2, r1 @ Convert C bytes to 0 + uqsub8 r5, ip, r3 + eor r7, r3, r1 + uqsub8 r6, ip, r6 @ Find C + sfi_pld r0, #128 @ Prefetch 2 lines ahead + uqsub8 r7, ip, r7 + orr r4, r4, r6 @ Combine found for EOS and C + orr r5, r5, r7 + orrs r6, r4, r5 @ Combine the two words + it eq + sfi_breg r0, \ + ldrdeq r2, r3, [\B], #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 contents of the word containing the match. + @ Adjust r4 to the found bits for the word containing the match. + cmp r4, #0 + sub r0, r0, #4 + itte eq + moveq r4, r5 + moveq r2, r3 + subne r0, r0, #4 + + @ Find the bit-offset of the match within the word. +#if defined(__ARMEL__) + @ For LE, swap the found word so clz searches from the little end. + rev r4, r4 +#else + @ For BE, byte swap the word to make it easier to extract the byte. + rev r2, r2 +#endif + @ We're counting 0x01 (not 0x80), so the bit offset is 7 too high. + clz r3, r4 + sub r3, r3, #7 + lsr r2, r2, r3 @ Shift down found byte + uxtb r1, r1 @ Undo replication of C + uxtb r2, r2 @ Extract found byte + add r0, r0, r3, lsr #3 @ Adjust the pointer to the found byte + + pop { r4, r5, r6, r7 } + cfi_adjust_cfa_offset (-16) + cfi_restore (r4) + cfi_restore (r5) + cfi_restore (r6) + cfi_restore (r7) + + @ Disambiguate between EOS and C. +99: + cmp r2, r1 + it ne + movne r0, #0 @ Found EOS, return NULL + bx lr + +END (strchr) + +weak_alias (strchr, index) +libc_hidden_builtin_def (strchr) |