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/*
Copyright (c) 2012 DataLab, s.l. <http://www.datalab.es>
This file is part of the cluster/ec translator for GlusterFS.
The cluster/ec translator for GlusterFS is free software: you can
redistribute it and/or modify it under the terms of the GNU General
Public License as published by the Free Software Foundation, either
version 3 of the License, or (at your option) any later version.
The cluster/ec translator for GlusterFS is distributed in the hope
that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the cluster/ec translator for GlusterFS. If not, see
<http://www.gnu.org/licenses/>.
*/
#include <string.h>
#include <inttypes.h>
#include "ec-method.h"
#define EC_METHOD_WORD_SIZE 16
static uint32_t GfPow[EC_METHOD_SIZE << 1];
static uint32_t GfLog[EC_METHOD_SIZE << 1];
void ec_method_initialize(void)
{
uint32_t i;
GfPow[0] = 1;
GfLog[0] = EC_METHOD_SIZE;
for (i = 1; i < EC_METHOD_SIZE; i++)
{
GfPow[i] = GfPow[i - 1] << 1;
if (GfPow[i] >= EC_METHOD_SIZE)
{
GfPow[i] ^= EC_GF_MOD;
}
GfPow[i + EC_METHOD_SIZE - 1] = GfPow[i];
GfLog[GfPow[i] + EC_METHOD_SIZE - 1] = GfLog[GfPow[i]] = i;
}
}
static uint32_t ec_method_mul(uint32_t a, uint32_t b)
{
if (a && b)
{
return GfPow[GfLog[a] + GfLog[b]];
}
return 0;
}
static uint32_t ec_method_div(uint32_t a, uint32_t b)
{
if (b)
{
if (a)
{
return GfPow[EC_METHOD_SIZE - 1 + GfLog[a] - GfLog[b]];
}
return 0;
}
return EC_METHOD_SIZE;
}
size_t ec_method_encode(size_t size, uint32_t columns, uint32_t row,
uint8_t * in, uint8_t * out)
{
uint32_t i, j;
size /= EC_METHOD_CHUNK_SIZE * columns;
row++;
for (j = 0; j < size; j++)
{
ec_gf_load(in);
in += EC_METHOD_CHUNK_SIZE;
for (i = 1; i < columns; i++)
{
ec_gf_mul_table[row]();
ec_gf_xor(in);
in += EC_METHOD_CHUNK_SIZE;
}
ec_gf_store(out);
out += EC_METHOD_CHUNK_SIZE;
}
return size * EC_METHOD_CHUNK_SIZE;
}
size_t ec_method_decode(size_t size, uint32_t columns, uint32_t * rows,
uint8_t ** in, uint8_t * out)
{
uint32_t i, j, k;
uint32_t f, off, mask;
uint8_t inv[EC_METHOD_MAX_FRAGMENTS][EC_METHOD_MAX_FRAGMENTS + 1];
uint8_t mtx[EC_METHOD_MAX_FRAGMENTS][EC_METHOD_MAX_FRAGMENTS];
uint8_t * p[EC_METHOD_MAX_FRAGMENTS];
size /= EC_METHOD_CHUNK_SIZE;
memset(inv, 0, sizeof(inv));
memset(mtx, 0, sizeof(mtx));
mask = 0;
for (i = 0; i < columns; i++)
{
inv[i][i] = 1;
inv[i][columns] = 1;
}
k = 0;
for (i = 0; i < columns; i++)
{
while ((mask & 1) != 0)
{
k++;
mask >>= 1;
}
mtx[k][columns - 1] = 1;
for (j = columns - 1; j > 0; j--)
{
mtx[k][j - 1] = ec_method_mul(mtx[k][j], rows[i] + 1);
}
p[k] = in[i];
k++;
mask >>= 1;
}
for (i = 0; i < columns; i++)
{
f = mtx[i][i];
for (j = 0; j < columns; j++)
{
mtx[i][j] = ec_method_div(mtx[i][j], f);
inv[i][j] = ec_method_div(inv[i][j], f);
}
for (j = 0; j < columns; j++)
{
if (i != j)
{
f = mtx[j][i];
for (k = 0; k < columns; k++)
{
mtx[j][k] ^= ec_method_mul(mtx[i][k], f);
inv[j][k] ^= ec_method_mul(inv[i][k], f);
}
}
}
}
off = 0;
for (f = 0; f < size; f++)
{
for (i = 0; i < columns; i++)
{
ec_gf_load(p[0] + off);
j = 0;
while (j < columns)
{
k = j + 1;
while (inv[i][k] == 0)
{
k++;
}
ec_gf_mul_table[ec_method_div(inv[i][j], inv[i][k])]();
if (k < columns)
{
ec_gf_xor(p[k] + off);
}
j = k;
}
ec_gf_store(out);
out += EC_METHOD_CHUNK_SIZE;
in[i] += EC_METHOD_CHUNK_SIZE;
}
off += EC_METHOD_CHUNK_SIZE;
}
return size * EC_METHOD_CHUNK_SIZE * columns;
}
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