mirror of https://gitee.com/openkylin/linux.git
97 lines
2.6 KiB
ArmAsm
97 lines
2.6 KiB
ArmAsm
|
/*
|
||
|
|
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License version 2 as
|
||
|
|
* published by the Free Software Foundation.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* 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. */
|
||
|
|
|
||
|
|
#include <asm/linkage.h>
|
||
|
|
|
||
|
|
ARC_ENTRY 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 /* 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:
|
||
|
|
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
|
||
|
|
ARC_EXIT strcmp
|