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/*
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 "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;
}
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