summaryrefslogtreecommitdiffstats
path: root/xlators/cluster/ec/src/ec-galois.c
blob: 8cb4dc2e4e30e6a171c1baa96c466cfdf5d6b79d (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
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
/*
  Copyright (c) 2015 DataLab, s.l. <http://www.datalab.es>
  This file is part of GlusterFS.

  This file is licensed to you under your choice of the GNU Lesser
  General Public License, version 3 or any later version (LGPLv3 or
  later), or the GNU General Public License, version 2 (GPLv2), in all
  cases as published by the Free Software Foundation.
*/

#include <string.h>

#include "mem-pool.h"
#include "list.h"

#include "ec-mem-types.h"
#include "ec-gf8.h"
#include "ec-helpers.h"

static ec_gf_t *
ec_gf_alloc(uint32_t bits, uint32_t mod)
{
    ec_gf_t *gf;

    gf = GF_MALLOC(sizeof(ec_gf_t), ec_mt_ec_gf_t);
    if (gf == NULL) {
        goto failed;
    }

    gf->bits = bits;
    gf->size = 1 << bits;
    gf->mod = mod;

    gf->log = GF_MALLOC(sizeof(uint32_t) * (gf->size * 2 - 1),
                        gf_common_mt_int);
    if (gf->log == NULL) {
        goto failed_gf;
    }
    gf->pow = GF_MALLOC(sizeof(uint32_t) * (gf->size * 2 - 1),
                        gf_common_mt_int);
    if (gf->pow == NULL) {
        goto failed_log;
    }

    return gf;

failed_log:
    GF_FREE(gf->log);
failed_gf:
    GF_FREE(gf);
failed:
    return EC_ERR(ENOMEM);
}

static void
ec_gf_init_tables(ec_gf_t *gf)
{
    uint32_t i, tmp;

    memset(gf->log, -1, sizeof(uint32_t) * gf->size);

    gf->pow[0] = 1;
    gf->log[0] = gf->size;
    gf->log[1] = 0;
    for (i = 1; i < gf->size; i++) {
        tmp = gf->pow[i - 1] << 1;
        if (tmp >= gf->size) {
            tmp ^= gf->mod;
        }
        gf->pow[i + gf->size - 1] = gf->pow[i] = tmp;
        gf->log[tmp + gf->size - 1] = gf->log[tmp] = i;
    }
}

ec_gf_t *
ec_gf_prepare(uint32_t bits, uint32_t mod)
{
    ec_gf_mul_t **tbl;
    ec_gf_t *gf;
    uint32_t i, j;

    if (bits != 8) {
        return EC_ERR(EINVAL);
    }

    tbl = ec_gf8_mul;
    if (mod == 0) {
        mod = 0x11d;
    }

    gf = ec_gf_alloc(bits, mod);
    if (EC_IS_ERR(gf)) {
        return gf;
    }
    ec_gf_init_tables(gf);

    gf->table = tbl;
    gf->min_ops = bits * bits;
    gf->max_ops = 0;
    gf->avg_ops = 0;
    for (i = 1; i < gf->size; i++) {
        for (j = 0; tbl[i]->ops[j].op != EC_GF_OP_END; j++) {
        }
        if (gf->max_ops < j) {
            gf->max_ops = j;
        }
        if (gf->min_ops > j) {
            gf->min_ops = j;
        }
        gf->avg_ops += j;
    }
    gf->avg_ops /= gf->size;

    return gf;
}

void
ec_gf_destroy(ec_gf_t *gf)
{
    GF_FREE(gf->pow);
    GF_FREE(gf->log);
    GF_FREE(gf);
}

uint32_t
ec_gf_add(ec_gf_t *gf, uint32_t a, uint32_t b)
{
    if ((a >= gf->size) || (b >= gf->size)) {
        return gf->size;
    }

    return a ^ b;
}

uint32_t
ec_gf_mul(ec_gf_t *gf, uint32_t a, uint32_t b)
{
    if ((a >= gf->size) || (b >= gf->size)) {
        return gf->size;
    }

    if ((a != 0) && (b != 0)) {
        return gf->pow[gf->log[a] + gf->log[b]];
    }

    return 0;
}

uint32_t
ec_gf_div(ec_gf_t *gf, uint32_t a, uint32_t b)
{
    if ((a >= gf->size) || (b >= gf->size)) {
        return gf->size;
    }

    if (b != 0) {
        if (a != 0) {
            return gf->pow[gf->size - 1 + gf->log[a] - gf->log[b]];
        }

        return 0;
    }

    return gf->size;
}

uint32_t
ec_gf_exp(ec_gf_t *gf, uint32_t a, uint32_t b)
{
    uint32_t r;

    if ((a >= gf->size) || ((a == 0) && (b == 0))) {
        return gf->size;
    }

    r = 1;
    while (b != 0) {
        if ((b & 1) != 0) {
            r = ec_gf_mul(gf, r, a);
        }
        a = ec_gf_mul(gf, a, a);
        b >>= 1;
    }

    return r;
}