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99 lines
3.1 KiB
99 lines
3.1 KiB
10 years ago
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/*
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* Mini Object Storage, (C) 2014 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <erasure-code.h>
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#include "matrix_decode.h"
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static int src_in_err (int r, int *src_err_list)
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{
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int i;
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for (i = 0; src_err_list[i] != -1; i++) {
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if (src_err_list[i] == r) {
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return 1;
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}
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}
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// false
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return 0;
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}
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/*
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Generate decode matrix during the decoding phase
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*/
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int gf_gen_decode_matrix (int *src_err_list,
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unsigned char *encode_matrix,
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unsigned char *decode_matrix,
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int k, int n, int errs,
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size_t matrix_size)
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{
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int i, j, r, s, l, z;
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unsigned char *input_matrix = NULL;
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unsigned char *inverse_matrix = NULL;
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input_matrix = malloc(k * n);
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if (!input_matrix) {
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return -1;
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}
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inverse_matrix = malloc(matrix_size);
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if (!inverse_matrix) {
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return -1;
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}
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for (i = 0, r = 0; i < k; i++, r++) {
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while (src_in_err(r, src_err_list))
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r++;
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for (j = 0; j < k; j++) {
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input_matrix[k * i + j] = encode_matrix[k * r + j];
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}
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}
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// Not all Vandermonde matrix can be inverted
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if (gf_invert_matrix(input_matrix, inverse_matrix, k) < 0) {
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return -1;
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}
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for (l = 0; l < errs; l++) {
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if (src_err_list[l] < k) {
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// decoding matrix elements for data chunks
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for (j = 0; j < k; j++) {
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decode_matrix[k * l + j] =
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inverse_matrix[k *
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src_err_list[l] + j];
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}
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} else {
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int s = 0;
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// decoding matrix element for coding chunks
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for (i = 0; i < k; i++) {
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s = 0;
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for (j = 0; j < k; j++) {
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s ^= gf_mul(inverse_matrix[j * k + i],
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encode_matrix[k *
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src_err_list[l] + j]);
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}
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decode_matrix[k * l + i] = s;
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}
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}
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}
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free(input_matrix);
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free(inverse_matrix);
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return 0;
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}
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