1 /* 2 * fec.c -- forward error correction based on Vandermonde matrices 3 * 980614 4 * (C) 1997-98 Luigi Rizzo (luigi@iet.unipi.it) 5 * 6 * Portions derived from code by Phil Karn (karn@ka9q.ampr.org), 7 * Robert Morelos-Zaragoza (robert@spectra.eng.hawaii.edu) and Hari 8 * Thirumoorthy (harit@spectra.eng.hawaii.edu), Aug 1995 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above 17 * copyright notice, this list of conditions and the following 18 * disclaimer in the documentation and/or other materials 19 * provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 23 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 24 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS 25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 28 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 30 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 32 * OF SUCH DAMAGE. 33 */ 34 35 /* 36 * The following parameter defines how many bits are used for 37 * field elements. The code supports any value from 2 to 16 38 * but fastest operation is achieved with 8 bit elements 39 * This is the only parameter you may want to change. 40 */ 41 #ifndef GF_BITS 42 #define GF_BITS 8 /* code over GF(2**GF_BITS) - change to suit */ 43 #endif 44 45 #define GF_SIZE ((1 << GF_BITS) - 1) /* powers of \alpha */ 46 47 void *fec_new(int k, int n); 48 void fec_free(void *p); 49 50 void fec_encode(void *code, u_char **src, u_char *dst, int index, int sz); 51 int fec_decode(void *code, u_char **pkt, int *index, int sz); 52