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/*
Copyright (c) 2015, Synopsys, Inc. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1) Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2) 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.
3) Neither the name of the Synopsys, Inc., 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.
*/
/* This implementation is optimized for performance. For code size a generic
implementation of this function from newlib/libc/string/strcmp.c will be
used. */
#if !defined (__OPTIMIZE_SIZE__) && !defined (PREFER_SIZE_OVER_SPEED)
#include "asm.h"
/* This is optimized primarily for the ARC700.
It would be possible to speed up the loops by one cycle / word
respective one cycle / byte by forcing double source 1 alignment, unrolling
by a factor of two, and speculatively loading the second word / byte of
source 1; however, that would increase the overhead for loop setup / finish,
and strcmp might often terminate early. */
#ifndef __ARCHS__
ENTRY (strcmp)
or r2,r0,r1
bmsk_s r2,r2,1
brne_l r2,0,.Lcharloop
mov_s r12,0x01010101
ror r5,r12
.Lwordloop:
ld.ab r2,[r0,4]
ld.ab r3,[r1,4]
nop_s
sub r4,r2,r12
bic r4,r4,r2
and r4,r4,r5
brne_l r4,0,.Lfound0
breq r2,r3,.Lwordloop
#ifdef __LITTLE_ENDIAN__
xor r0,r2,r3 ; mask for difference
sub_s r1,r0,1
bic_s r0,r0,r1 ; mask for least significant difference bit
sub r1,r5,r0
xor r0,r5,r1 ; mask for least significant difference byte
and_s r2,r2,r0
and_s r3,r3,r0
#endif /* LITTLE ENDIAN */
cmp_s r2,r3
mov_s r0,1
j_s.d [blink]
bset.lo r0,r0,31
.balign 4
#ifdef __LITTLE_ENDIAN__
.Lfound0:
xor r0,r2,r3 ; mask for difference
or r0,r0,r4 ; or in zero indicator
sub_s r1,r0,1
bic_s r0,r0,r1 ; mask for least significant difference bit
sub r1,r5,r0
xor r0,r5,r1 ; mask for least significant difference byte
and_s r2,r2,r0
and_s r3,r3,r0
sub.f r0,r2,r3
mov.hi r0,1
j_s.d [blink]
bset.lo r0,r0,31
#else /* BIG ENDIAN */
/* The zero-detection above can mis-detect 0x01 bytes as zeroes
because of carry-propagateion from a lower significant zero byte.
We can compensate for this by checking that bit0 is zero.
This compensation is not necessary in the step where we
get a low estimate for r2, because in any affected bytes
we already have 0x00 or 0x01, which will remain unchanged
when bit 7 is cleared. */
.balign 4
.Lfound0:
#ifdef __ARC_BARREL_SHIFTER__
lsr r0,r4,8
lsr_s r1,r2
bic_s r2,r2,r0 ; get low estimate for r2 and get ...
bic_s r0,r0,r1 ; <this is the adjusted mask for zeros>
or_s r3,r3,r0 ; ... high estimate r3 so that r2 > r3 will ...
cmp_s r3,r2 ; ... be independent of trailing garbage
or_s r2,r2,r0 ; likewise for r3 > r2
bic_s r3,r3,r0
rlc r0,0 ; r0 := r2 > r3 ? 1 : 0
cmp_s r2,r3
j_s.d [blink]
bset.lo r0,r0,31
#else /* __ARC_BARREL_SHIFTER__ */
/* Fall through to .Lcharloop. */
sub_s r0,r0,4
sub_s r1,r1,4
#endif /* __ARC_BARREL_SHIFTER__ */
#endif /* ENDIAN */
.balign 4
.Lcharloop:
ldb.ab r2,[r0,1]
ldb.ab r3,[r1,1]
nop_s
breq_l r2,0,.Lcmpend
breq r2,r3,.Lcharloop
.Lcmpend:
j_s.d [blink]
sub r0,r2,r3
ENDFUNC (strcmp)
#endif /* !__ARCHS__ */
#endif /* !__OPTIMIZE_SIZE__ && !PREFER_SIZE_OVER_SPEED */
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