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- /*
- * 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 <linux/linkage.h>
- ENTRY_CFI(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
- END_CFI(strcmp)
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