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| /* SPDX-License-Identifier: GPL-2.0-only */
| /*
| * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
| */
|
| /* 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)
|
|
