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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
* Reed-Solomon codecs, based on libfec
*
* Copyright (C) 2004 Phil Karn, KA9Q
* libcryptsetup modifications
* Copyright (C) 2017-2025 Red Hat, Inc. All rights reserved.
*/
#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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