50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
// SPDX-License-Identifier: LGPL-2.1-or-later
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/*
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* Reed-Solomon codecs, based on libfec
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*
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* Copyright (C) 2004 Phil Karn, KA9Q
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* libcryptsetup modifications
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* Copyright (C) 2017-2024 Red Hat, Inc. All rights reserved.
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*/
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#ifndef _LIBFEC_RS_H
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#define _LIBFEC_RS_H
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/* Special reserved value encoding zero in index form. */
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#define A0 (rs->nn)
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#define RS_MIN(a, b) ((a) < (b) ? (a) : (b))
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typedef unsigned char data_t;
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/* Reed-Solomon codec control block */
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struct rs {
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int mm; /* Bits per symbol */
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int nn; /* Symbols per block (= (1<<mm)-1) */
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data_t *alpha_to;/* log lookup table */
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data_t *index_of;/* Antilog lookup table */
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data_t *genpoly; /* Generator polynomial */
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int nroots; /* Number of generator roots = number of parity symbols */
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int fcr; /* First consecutive root, index form */
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int prim; /* Primitive element, index form */
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int iprim; /* prim-th root of 1, index form */
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int pad; /* Padding bytes in shortened block */
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};
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static inline int modnn(struct rs *rs, int x)
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{
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while (x >= rs->nn) {
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x -= rs->nn;
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x = (x >> rs->mm) + (x & rs->nn);
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}
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return x;
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}
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struct rs *init_rs_char(int symsize, int gfpoly, int fcr, int prim, int nroots, int pad);
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void free_rs_char(struct rs *rs);
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/* General purpose RS codec, 8-bit symbols */
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void encode_rs_char(struct rs *rs, data_t *data, data_t *parity);
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int decode_rs_char(struct rs *rs, data_t *data);
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#endif
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