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/*
* Copyright (C) 2004, 2007-2010, 2011-2014 Synopsys, Inc. All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* 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.
*/
.global strcmp
.align 4
strcmp:
or %r2, %r0, %r1
bmsk_s %r2, %r2, 1
brne %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 %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 /* _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:
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
#endif /* _ENDIAN__ */
.balign 4
.Lcharloop:
ldb.ab %r2,[%r0,1]
ldb.ab %r3,[%r1,1]
nop_s
breq %r2, 0, .Lcmpend
breq %r2, %r3, .Lcharloop
.Lcmpend:
j_s.d [%blink]
sub %r0, %r2, %r3
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