178 lines
5.2 KiB
C
178 lines
5.2 KiB
C
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/* Examples/reed_sol_01.c
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Jerasure - A C/C++ Library for a Variety of Reed-Solomon and RAID-6 Erasure Coding Techniques
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Revision 1.2A
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May 24, 2011
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James S. Plank
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Department of Electrical Engineering and Computer Science
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University of Tennessee
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Knoxville, TN 37996
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plank@cs.utk.edu
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Copyright (c) 2011, James S. Plank
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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distribution.
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- Neither the name of the University of Tennessee nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
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WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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revised by S. Simmerman
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2/25/08
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "jerasure.h"
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#include "reed_sol.h"
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#define talloc(type, num) (type *) malloc(sizeof(type)*(num))
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usage(char *s)
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{
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fprintf(stderr, "usage: reed_sol_01 k m w - Does a simple Reed-Solomon coding example in GF(2^w).\n");
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fprintf(stderr, " \n");
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fprintf(stderr, " w must be 8, 16 or 32. k+m must be <= 2^w. It sets up a classic\n");
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fprintf(stderr, " Vandermonde-based distribution matrix and encodes k devices of\n");
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fprintf(stderr, " %d bytes each with it. Then it decodes.\n", sizeof(long));
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fprintf(stderr, " \n");
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fprintf(stderr, "This demonstrates: jerasure_matrix_encode()\n");
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fprintf(stderr, " jerasure_matrix_decode()\n");
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fprintf(stderr, " jerasure_print_matrix()\n");
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fprintf(stderr, " reed_sol_vandermonde_coding_matrix()\n");
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if (s != NULL) fprintf(stderr, "%s\n", s);
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exit(1);
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}
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static void print_data_and_coding(int k, int m, int w, int size,
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char **data, char **coding)
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{
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int i, j, x;
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int n, sp;
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long l;
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if(k > m) n = k;
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else n = m;
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sp = size * 2 + size/(w/8) + 8;
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printf("%-*sCoding\n", sp, "Data");
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for(i = 0; i < n; i++) {
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if(i < k) {
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printf("D%-2d:", i);
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for(j=0;j< size; j+=(w/8)) {
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printf(" ");
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for(x=0;x < w/8;x++){
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printf("%02x", (unsigned char)data[i][j+x]);
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}
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}
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printf(" ");
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}
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else printf("%*s", sp, "");
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if(i < m) {
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printf("C%-2d:", i);
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for(j=0;j< size; j+=(w/8)) {
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printf(" ");
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for(x=0;x < w/8;x++){
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printf("%02x", (unsigned char)coding[i][j+x]);
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}
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}
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}
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printf("\n");
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}
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printf("\n");
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}
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int main(int argc, char **argv)
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{
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long l;
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int k, w, i, j, m;
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int *matrix;
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char **data, **coding;
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int *erasures, *erased;
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int *decoding_matrix, *dm_ids;
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if (argc != 4) usage(NULL);
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if (sscanf(argv[1], "%d", &k) == 0 || k <= 0) usage("Bad k");
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if (sscanf(argv[2], "%d", &m) == 0 || m <= 0) usage("Bad m");
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if (sscanf(argv[3], "%d", &w) == 0 || (w != 8 && w != 16 && w != 32)) usage("Bad w");
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if (w <= 16 && k + m > (1 << w)) usage("k + m is too big");
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matrix = reed_sol_vandermonde_coding_matrix(k, m, w);
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printf("Last m rows of the Distribution Matrix:\n\n");
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jerasure_print_matrix(matrix, m, k, w);
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printf("\n");
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srand48(0);
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data = talloc(char *, k);
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for (i = 0; i < k; i++) {
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data[i] = talloc(char, sizeof(long));
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l = lrand48();
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memcpy(data[i], &l, sizeof(long));
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}
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coding = talloc(char *, m);
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for (i = 0; i < m; i++) {
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coding[i] = talloc(char, sizeof(long));
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}
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jerasure_matrix_encode(k, m, w, matrix, data, coding, sizeof(long));
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printf("Encoding Complete:\n\n");
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print_data_and_coding(k, m, w, sizeof(long), data, coding);
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erasures = talloc(int, (m+1));
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erased = talloc(int, (k+m));
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for (i = 0; i < m+k; i++) erased[i] = 0;
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l = 0;
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for (i = 0; i < m; ) {
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erasures[i] = lrand48()%(k+m);
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if (erased[erasures[i]] == 0) {
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erased[erasures[i]] = 1;
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memcpy((erasures[i] < k) ? data[erasures[i]] : coding[erasures[i]-k], &l, sizeof(long));
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i++;
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}
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}
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erasures[i] = -1;
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printf("Erased %d random devices:\n\n", m);
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print_data_and_coding(k, m, w, sizeof(long), data, coding);
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i = jerasure_matrix_decode(k, m, w, matrix, 1, erasures, data, coding, sizeof(long));
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printf("State of the system after decoding:\n\n");
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print_data_and_coding(k, m, w, sizeof(long), data, coding);
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return 0;
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}
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