| rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | /* This is optimized primarily for the ARC700. |
| 10 | It would be possible to speed up the loops by one cycle / word |
| 11 | respective one cycle / byte by forcing double source 1 alignment, unrolling |
| 12 | by a factor of two, and speculatively loading the second word / byte of |
| 13 | source 1; however, that would increase the overhead for loop setup / finish, |
| 14 | and strcmp might often terminate early. */ |
| 15 | |
| 16 | #include <linux/linkage.h> |
| 17 | |
| 18 | ENTRY_CFI(strcmp) |
| 19 | or r2,r0,r1 |
| 20 | bmsk_s r2,r2,1 |
| 21 | brne r2,0,.Lcharloop |
| 22 | mov_s r12,0x01010101 |
| 23 | ror r5,r12 |
| 24 | .Lwordloop: |
| 25 | ld.ab r2,[r0,4] |
| 26 | ld.ab r3,[r1,4] |
| 27 | nop_s |
| 28 | sub r4,r2,r12 |
| 29 | bic r4,r4,r2 |
| 30 | and r4,r4,r5 |
| 31 | brne r4,0,.Lfound0 |
| 32 | breq r2,r3,.Lwordloop |
| 33 | #ifdef __LITTLE_ENDIAN__ |
| 34 | xor r0,r2,r3 ; mask for difference |
| 35 | sub_s r1,r0,1 |
| 36 | bic_s r0,r0,r1 ; mask for least significant difference bit |
| 37 | sub r1,r5,r0 |
| 38 | xor r0,r5,r1 ; mask for least significant difference byte |
| 39 | and_s r2,r2,r0 |
| 40 | and_s r3,r3,r0 |
| 41 | #endif /* LITTLE ENDIAN */ |
| 42 | cmp_s r2,r3 |
| 43 | mov_s r0,1 |
| 44 | j_s.d [blink] |
| 45 | bset.lo r0,r0,31 |
| 46 | |
| 47 | .balign 4 |
| 48 | #ifdef __LITTLE_ENDIAN__ |
| 49 | .Lfound0: |
| 50 | xor r0,r2,r3 ; mask for difference |
| 51 | or r0,r0,r4 ; or in zero indicator |
| 52 | sub_s r1,r0,1 |
| 53 | bic_s r0,r0,r1 ; mask for least significant difference bit |
| 54 | sub r1,r5,r0 |
| 55 | xor r0,r5,r1 ; mask for least significant difference byte |
| 56 | and_s r2,r2,r0 |
| 57 | and_s r3,r3,r0 |
| 58 | sub.f r0,r2,r3 |
| 59 | mov.hi r0,1 |
| 60 | j_s.d [blink] |
| 61 | bset.lo r0,r0,31 |
| 62 | #else /* BIG ENDIAN */ |
| 63 | /* The zero-detection above can mis-detect 0x01 bytes as zeroes |
| 64 | because of carry-propagateion from a lower significant zero byte. |
| 65 | We can compensate for this by checking that bit0 is zero. |
| 66 | This compensation is not necessary in the step where we |
| 67 | get a low estimate for r2, because in any affected bytes |
| 68 | we already have 0x00 or 0x01, which will remain unchanged |
| 69 | when bit 7 is cleared. */ |
| 70 | .balign 4 |
| 71 | .Lfound0: |
| 72 | lsr r0,r4,8 |
| 73 | lsr_s r1,r2 |
| 74 | bic_s r2,r2,r0 ; get low estimate for r2 and get ... |
| 75 | bic_s r0,r0,r1 ; <this is the adjusted mask for zeros> |
| 76 | or_s r3,r3,r0 ; ... high estimate r3 so that r2 > r3 will ... |
| 77 | cmp_s r3,r2 ; ... be independent of trailing garbage |
| 78 | or_s r2,r2,r0 ; likewise for r3 > r2 |
| 79 | bic_s r3,r3,r0 |
| 80 | rlc r0,0 ; r0 := r2 > r3 ? 1 : 0 |
| 81 | cmp_s r2,r3 |
| 82 | j_s.d [blink] |
| 83 | bset.lo r0,r0,31 |
| 84 | #endif /* ENDIAN */ |
| 85 | |
| 86 | .balign 4 |
| 87 | .Lcharloop: |
| 88 | ldb.ab r2,[r0,1] |
| 89 | ldb.ab r3,[r1,1] |
| 90 | nop_s |
| 91 | breq r2,0,.Lcmpend |
| 92 | breq r2,r3,.Lcharloop |
| 93 | .Lcmpend: |
| 94 | j_s.d [blink] |
| 95 | sub r0,r2,r3 |
| 96 | END_CFI(strcmp) |