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3e3d5815 AZ |
1 | /* |
2 | * Calculate Error-correcting Codes. Used by NAND Flash controllers | |
3 | * (not by NAND chips). | |
4 | * | |
5 | * Copyright (c) 2006 Openedhand Ltd. | |
6 | * Written by Andrzej Zaborowski <balrog@zabor.org> | |
7 | * | |
8 | * This code is licensed under the GNU GPL v2. | |
9 | */ | |
10 | ||
11 | struct ecc_state_s { | |
12 | uint8_t cp; /* Column parity */ | |
13 | uint16_t lp[2]; /* Line parity */ | |
14 | uint16_t count; | |
15 | }; | |
16 | ||
17 | /* | |
18 | * Pre-calculated 256-way 1 byte column parity. Table borrowed from Linux. | |
19 | */ | |
20 | static const uint8_t nand_ecc_precalc_table[] = { | |
21 | 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, | |
22 | 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, | |
23 | 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, | |
24 | 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, | |
25 | 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, | |
26 | 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, | |
27 | 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, | |
28 | 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, | |
29 | 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, | |
30 | 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, | |
31 | 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, | |
32 | 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, | |
33 | 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, | |
34 | 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, | |
35 | 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, | |
36 | 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, | |
37 | 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, | |
38 | 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, | |
39 | 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, | |
40 | 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, | |
41 | 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, | |
42 | 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, | |
43 | 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, | |
44 | 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, | |
45 | 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, | |
46 | 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, | |
47 | 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, | |
48 | 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, | |
49 | 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, | |
50 | 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, | |
51 | 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, | |
52 | 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, | |
53 | }; | |
54 | ||
55 | /* Update ECC parity count. */ | |
56 | static inline uint8_t ecc_digest(struct ecc_state_s *s, uint8_t sample) | |
57 | { | |
58 | uint8_t idx = nand_ecc_precalc_table[sample]; | |
59 | ||
60 | s->cp ^= idx & 0x3f; | |
61 | if (idx & 0x40) { | |
62 | s->lp[0] ^= ~s->count; | |
63 | s->lp[1] ^= s->count; | |
64 | } | |
65 | s->count ++; | |
66 | ||
67 | return sample; | |
68 | } | |
69 | ||
70 | /* Reinitialise the counters. */ | |
71 | static inline void ecc_reset(struct ecc_state_s *s) | |
72 | { | |
73 | s->lp[0] = 0x0000; | |
74 | s->lp[1] = 0x0000; | |
75 | s->cp = 0x00; | |
76 | s->count = 0; | |
77 | } | |
aa941b94 AZ |
78 | |
79 | /* Save/restore */ | |
80 | static inline void ecc_put(QEMUFile *f, struct ecc_state_s *s) | |
81 | { | |
82 | qemu_put_8s(f, &s->cp); | |
83 | qemu_put_be16s(f, &s->lp[0]); | |
84 | qemu_put_be16s(f, &s->lp[1]); | |
85 | qemu_put_be16s(f, &s->count); | |
86 | } | |
87 | ||
88 | static inline void ecc_get(QEMUFile *f, struct ecc_state_s *s) | |
89 | { | |
90 | qemu_get_8s(f, &s->cp); | |
91 | qemu_get_be16s(f, &s->lp[0]); | |
92 | qemu_get_be16s(f, &s->lp[1]); | |
93 | qemu_get_be16s(f, &s->count); | |
94 | } |