fec.h

/*
 * fec.c -- forward error correction based on Vandermonde matrices
 * 980614
 * (C) 1997-98 Luigi Rizzo (luigi@iet.unipi.it)
 *
 * Portions derived from code by Phil Karn (karn@ka9q.ampr.org),
 * Robert Morelos-Zaragoza (robert@spectra.eng.hawaii.edu) and Hari
 * Thirumoorthy (harit@spectra.eng.hawaii.edu), Aug 1995
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */
 
/*
 * The following parameter defines how many bits are used for
 * field elements. The code supports any value from 2 to 16
 * but fastest operation is achieved with 8 bit elements
 * This is the only parameter you may want to change.
 */
#ifndef GF_BITS
#define GF_BITS 8 /* code over GF(2**GF_BITS) - change to suit */
#endif
 
#if (GF_BITS <= 8)
typedef unsigned char gf;
#else
typedef unsigned short gf;
#endif
 
#define GF_SIZE ((1 << GF_BITS) - 1) /* powers of \alpha */
 
struct fec_parms {
  unsigned long magic;
  int k, n; /* parameters of the code */
  gf *enc_matrix;
};
 
void fec_free(struct fec_parms *p);
struct fec_parms *fec_new(int k, int n);
 
void fec_encode(struct fec_parms *code, gf *src[], gf *fec, int index, int sz);
int fec_decode(struct fec_parms *code, gf *pkt[], int index[], int sz);
 
/* end of file */