summaryrefslogtreecommitdiff
path: root/ecc.h
blob: e8e39426f5778ca79720f70a09e3ce1c5ba02c2b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
/*
 * Calculate Error-correcting Codes. Used by NAND Flash controllers
 * (not by NAND chips).
 *
 * Copyright (c) 2006 Openedhand Ltd.
 * Written by Andrzej Zaborowski <balrog@zabor.org>
 *
 * This code is licensed under the GNU GPL v2.
 */

struct ecc_state_s {
    uint8_t cp;		/* Column parity */
    uint16_t lp[2];	/* Line parity */
    uint16_t count;
};

/*
 * Pre-calculated 256-way 1 byte column parity.  Table borrowed from Linux.
 */
static const uint8_t nand_ecc_precalc_table[] = {
    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
    0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
    0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
    0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
    0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
    0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
    0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
    0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
    0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
    0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
    0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
    0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
    0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
    0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
    0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
    0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
    0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
    0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
    0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
    0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
    0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
    0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
    0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
    0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
    0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
    0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
    0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
    0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
    0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
};

/* Update ECC parity count.  */
static inline uint8_t ecc_digest(struct ecc_state_s *s, uint8_t sample)
{
    uint8_t idx = nand_ecc_precalc_table[sample];

    s->cp ^= idx & 0x3f;
    if (idx & 0x40) {
        s->lp[0] ^= ~s->count;
        s->lp[1] ^= s->count;
    }
    s->count ++;

    return sample;
}

/* Reinitialise the counters.  */
static inline void ecc_reset(struct ecc_state_s *s)
{
    s->lp[0] = 0x0000;
    s->lp[1] = 0x0000;
    s->cp = 0x00;
    s->count = 0;
}

/* Save/restore */
static inline void ecc_put(QEMUFile *f, struct ecc_state_s *s)
{
    qemu_put_8s(f, &s->cp);
    qemu_put_be16s(f, &s->lp[0]);
    qemu_put_be16s(f, &s->lp[1]);
    qemu_put_be16s(f, &s->count);
}

static inline void ecc_get(QEMUFile *f, struct ecc_state_s *s)
{
    qemu_get_8s(f, &s->cp);
    qemu_get_be16s(f, &s->lp[0]);
    qemu_get_be16s(f, &s->lp[1]);
    qemu_get_be16s(f, &s->count);
}