202 lines
6.9 KiB
ArmAsm
202 lines
6.9 KiB
ArmAsm
/* 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. */
|
|
|
|
/* Copyright (c) 2015 ARM Ltd.
|
|
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 the Linaro 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. */
|
|
|
|
@ 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
|
|
|
|
@ This code requires armv6t2 or later. Uses Thumb2.
|
|
|
|
.syntax unified
|
|
|
|
#include "acle-compat.h"
|
|
#include "arm_asm.h"
|
|
|
|
@ NOTE: This ifdef MUST match the one in memchr-stub.c
|
|
#if __ARM_ARCH_ISA_THUMB >= 2 && defined (__ARM_FEATURE_DSP)
|
|
|
|
#if __ARM_ARCH_PROFILE == 'M'
|
|
.arch armv7e-m
|
|
#else
|
|
.arch armv6t2
|
|
#endif
|
|
|
|
@ 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
|
|
#else
|
|
/* Defined in memchr-stub.c. */
|
|
#endif
|