/* * 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) |