diff options
author | Nick Clifton <nickc@redhat.com> | 2011-10-18 11:35:17 +0000 |
---|---|---|
committer | Nick Clifton <nickc@redhat.com> | 2011-10-18 11:35:17 +0000 |
commit | d6f6573a5ff9adbc16b76c5d91ba8f6ab401b822 (patch) | |
tree | 1af4a29cc88ab3ff3b012b42cb4cd8d774f13e7e /newlib/libc/machine/arm/memchr.S | |
parent | 53609fd238a7ba4e8e9b53378cef6087170add22 (diff) | |
download | cygnal-d6f6573a5ff9adbc16b76c5d91ba8f6ab401b822.tar.gz cygnal-d6f6573a5ff9adbc16b76c5d91ba8f6ab401b822.tar.bz2 cygnal-d6f6573a5ff9adbc16b76c5d91ba8f6ab401b822.zip |
* libc/machine/arm/Makefile.am (lib_a_SOURCES): Add memchr-stub.c,
memchr.S.
* libc/machine/arm/arm_asm.h: Add ifdef to allow it to be included
in .S files.
* libc/machine/arm/memchr-stub.c: New file - just selects what to
compile.
* libc/machine/arm/memchr.S: New file - ARMv6t2/v7 version.
* libc/machine/arm/Makefile.am (lib_a_SOURCES): Add strlen-armv7.S.
* libc/machine/arm/strlen-armv7.S: New file.
* libc/machine/arm/strlen.c: Add ifdef optimised code so it isn't
for v7 or 6t2.
* libc/machine/arm/Makefile.in: Regenerate.
Diffstat (limited to 'newlib/libc/machine/arm/memchr.S')
-rw-r--r-- | newlib/libc/machine/arm/memchr.S | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/newlib/libc/machine/arm/memchr.S b/newlib/libc/machine/arm/memchr.S new file mode 100644 index 000000000..56bfef09a --- /dev/null +++ b/newlib/libc/machine/arm/memchr.S @@ -0,0 +1,166 @@ +/* Copyright (c) 2010-2011, Linaro Limited + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. + + * Neither the name of Linaro Limited nor the names of its + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + + Written by Dave Gilbert <david.gilbert@linaro.org> + + This memchr routine is optimised on a Cortex-A9 and should work on + all ARMv7 processors. It has a fast path for short sizes, and has + an optimised path for large data sets; the worst case is finding the + match early in a large data set. */ + +@ 2011-02-07 david.gilbert@linaro.org +@ Extracted from local git a5b438d861 +@ 2011-07-14 david.gilbert@linaro.org +@ Import endianness fix from local git ea786f1b +@ 2011-10-11 david.gilbert@linaro.org +@ Import from cortex-strings bzr rev 63 +@ Flip to ldrd (as suggested by Greta Yorsh) +@ Make conditional on CPU type +@ tidy + + .syntax unified + .arch armv7-a + +#include "arm_asm.h" + +@ NOTE: This ifdef MUST match the one in memchr-stub.c +#if defined(_ISA_ARM_7) || defined(__ARM_ARCH_6T2__) + +@ this lets us check a flag in a 00/ff byte easily in either endianness +#ifdef __ARMEB__ +#define CHARTSTMASK(c) 1<<(31-(c*8)) +#else +#define CHARTSTMASK(c) 1<<(c*8) +#endif + .text + .thumb + +@ --------------------------------------------------------------------------- + .thumb_func + .align 2 + .p2align 4,,15 + .global memchr + .type memchr,%function +memchr: + @ r0 = start of memory to scan + @ r1 = character to look for + @ r2 = length + @ returns r0 = pointer to character or NULL if not found + and r1,r1,#0xff @ Don't trust the caller to pass a char + + cmp r2,#16 @ If short don't bother with anything clever + blt 20f + + tst r0, #7 @ If it's already aligned skip the next bit + beq 10f + + @ Work up to an aligned point +5: + ldrb r3, [r0],#1 + subs r2, r2, #1 + cmp r3, r1 + beq 50f @ If it matches exit found + tst r0, #7 + cbz r2, 40f @ If we run off the end, exit not found + bne 5b @ If not aligned yet then do next byte + +10: + @ We are aligned, we know we have at least 8 bytes to work with + push {r4,r5,r6,r7} + orr r1, r1, r1, lsl #8 @ expand the match word across all bytes + orr r1, r1, r1, lsl #16 + bic r4, r2, #7 @ Number of double words to work with * 8 + mvns r7, #0 @ all F's + movs r3, #0 + +15: + ldrd r5,r6,[r0],#8 + subs r4, r4, #8 + eor r5,r5, r1 @ r5,r6 have 00's where bytes match the target + eor r6,r6, r1 + uadd8 r5, r5, r7 @ Par add 0xff - sets GE bits for bytes!=0 + sel r5, r3, r7 @ bytes are 00 for none-00 bytes, + @ or ff for 00 bytes - NOTE INVERSION + uadd8 r6, r6, r7 @ Par add 0xff - sets GE bits for bytes!=0 + sel r6, r5, r7 @ chained....bytes are 00 for none-00 bytes + @ or ff for 00 bytes - NOTE INVERSION + cbnz r6, 60f + bne 15b @ (Flags from the subs above) + + pop {r4,r5,r6,r7} + and r1,r1,#0xff @ r1 back to a single character + and r2,r2,#7 @ Leave the count remaining as the number + @ after the double words have been done + +20: + cbz r2, 40f @ 0 length or hit the end already then not found + +21: @ Post aligned section, or just a short call + ldrb r3,[r0],#1 + subs r2,r2,#1 + eor r3,r3,r1 @ r3 = 0 if match - doesn't break flags from sub + cbz r3, 50f + bne 21b @ on r2 flags + +40: + movs r0,#0 @ not found + bx lr + +50: + subs r0,r0,#1 @ found + bx lr + +60: @ We're here because the fast path found a hit + @ now we have to track down exactly which word it was + @ r0 points to the start of the double word after the one tested + @ r5 has the 00/ff pattern for the first word, r6 has the chained value + cmp r5, #0 + itte eq + moveq r5, r6 @ the end is in the 2nd word + subeq r0,r0,#3 @ Points to 2nd byte of 2nd word + subne r0,r0,#7 @ or 2nd byte of 1st word + + @ r0 currently points to the 2nd byte of the word containing the hit + tst r5, # CHARTSTMASK(0) @ 1st character + bne 61f + adds r0,r0,#1 + tst r5, # CHARTSTMASK(1) @ 2nd character + ittt eq + addeq r0,r0,#1 + tsteq r5, # (3<<15) @ 2nd & 3rd character + @ If not the 3rd must be the last one + addeq r0,r0,#1 + +61: + pop {r4,r5,r6,r7} + subs r0,r0,#1 + bx lr + +#endif |