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5210d1e6 VG |
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 | ||
ec7ac6af | 16 | #include <linux/linkage.h> |
5210d1e6 | 17 | |
86effd0d | 18 | ENTRY_CFI(strcmp) |
5210d1e6 VG |
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 | |
86effd0d | 96 | END_CFI(strcmp) |