| /* |
| * 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(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(strcmp) |
