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Christian Hitz4c6de852011-10-12 09:31:59 +02001/*
2 * Generic binary BCH encoding/decoding library
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 as published by
6 * the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 51
15 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
16 *
17 * Copyright © 2011 Parrot S.A.
18 *
19 * Author: Ivan Djelic <ivan.djelic@parrot.com>
20 *
21 * Description:
22 *
23 * This library provides runtime configurable encoding/decoding of binary
24 * Bose-Chaudhuri-Hocquenghem (BCH) codes.
25*/
26#ifndef _BCH_H
27#define _BCH_H
28
29#include <linux/types.h>
30
31/**
32 * struct bch_control - BCH control structure
33 * @m: Galois field order
34 * @n: maximum codeword size in bits (= 2^m-1)
35 * @t: error correction capability in bits
36 * @ecc_bits: ecc exact size in bits, i.e. generator polynomial degree (<=m*t)
37 * @ecc_bytes: ecc max size (m*t bits) in bytes
38 * @a_pow_tab: Galois field GF(2^m) exponentiation lookup table
39 * @a_log_tab: Galois field GF(2^m) log lookup table
40 * @mod8_tab: remainder generator polynomial lookup tables
41 * @ecc_buf: ecc parity words buffer
42 * @ecc_buf2: ecc parity words buffer
43 * @xi_tab: GF(2^m) base for solving degree 2 polynomial roots
44 * @syn: syndrome buffer
45 * @cache: log-based polynomial representation buffer
46 * @elp: error locator polynomial
47 * @poly_2t: temporary polynomials of degree 2t
48 */
49struct bch_control {
50 unsigned int m;
51 unsigned int n;
52 unsigned int t;
53 unsigned int ecc_bits;
54 unsigned int ecc_bytes;
55/* private: */
56 uint16_t *a_pow_tab;
57 uint16_t *a_log_tab;
58 uint32_t *mod8_tab;
59 uint32_t *ecc_buf;
60 uint32_t *ecc_buf2;
61 unsigned int *xi_tab;
62 unsigned int *syn;
63 int *cache;
64 struct gf_poly *elp;
65 struct gf_poly *poly_2t[4];
66};
67
68struct bch_control *init_bch(int m, int t, unsigned int prim_poly);
69
70void free_bch(struct bch_control *bch);
71
72void encode_bch(struct bch_control *bch, const uint8_t *data,
73 unsigned int len, uint8_t *ecc);
74
75int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
76 const uint8_t *recv_ecc, const uint8_t *calc_ecc,
77 const unsigned int *syn, unsigned int *errloc);
78
79#endif /* _BCH_H */