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/*
* Reed-Solomon codecs, based on libfec
*
* Copyright (C) 2004 Phil Karn, KA9Q
* libcryptsetup modifications
* Copyright (C) 2017-2021 Red Hat, Inc. All rights reserved.
*
* This file is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This file 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this file; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _LIBFEC_RS_H
#define _LIBFEC_RS_H
/* Special reserved value encoding zero in index form. */
#define A0 (rs->nn)
#define RS_MIN(a, b) ((a) < (b) ? (a) : (b))
typedef unsigned char data_t;
/* Reed-Solomon codec control block */
struct rs {
int mm; /* Bits per symbol */
int nn; /* Symbols per block (= (1<<mm)-1) */
data_t *alpha_to;/* log lookup table */
data_t *index_of;/* Antilog lookup table */
data_t *genpoly; /* Generator polynomial */
int nroots; /* Number of generator roots = number of parity symbols */
int fcr; /* First consecutive root, index form */
int prim; /* Primitive element, index form */
int iprim; /* prim-th root of 1, index form */
int pad; /* Padding bytes in shortened block */
};
static inline int modnn(struct rs *rs, int x)
{
while (x >= rs->nn) {
x -= rs->nn;
x = (x >> rs->mm) + (x & rs->nn);
}
return x;
}
struct rs *init_rs_char(int symsize, int gfpoly, int fcr, int prim, int nroots, int pad);
void free_rs_char(struct rs *rs);
/* General purpose RS codec, 8-bit symbols */
void encode_rs_char(struct rs *rs, data_t *data, data_t *parity);
int decode_rs_char(struct rs *rs, data_t *data);
#endif
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