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Christian Hitz4c6de852011-10-12 09:31:59 +02001/*
2 * Generic binary BCH encoding/decoding library
3 *
Tom Rini5b8031c2016-01-14 22:05:13 -05004 * SPDX-License-Identifier: GPL-2.0
Christian Hitz4c6de852011-10-12 09:31:59 +02005 *
6 * Copyright © 2011 Parrot S.A.
7 *
8 * Author: Ivan Djelic <ivan.djelic@parrot.com>
9 *
10 * Description:
11 *
12 * This library provides runtime configurable encoding/decoding of binary
13 * Bose-Chaudhuri-Hocquenghem (BCH) codes.
14*/
15#ifndef _BCH_H
16#define _BCH_H
17
18#include <linux/types.h>
19
20/**
21 * struct bch_control - BCH control structure
22 * @m: Galois field order
23 * @n: maximum codeword size in bits (= 2^m-1)
24 * @t: error correction capability in bits
25 * @ecc_bits: ecc exact size in bits, i.e. generator polynomial degree (<=m*t)
26 * @ecc_bytes: ecc max size (m*t bits) in bytes
27 * @a_pow_tab: Galois field GF(2^m) exponentiation lookup table
28 * @a_log_tab: Galois field GF(2^m) log lookup table
29 * @mod8_tab: remainder generator polynomial lookup tables
30 * @ecc_buf: ecc parity words buffer
31 * @ecc_buf2: ecc parity words buffer
32 * @xi_tab: GF(2^m) base for solving degree 2 polynomial roots
33 * @syn: syndrome buffer
34 * @cache: log-based polynomial representation buffer
35 * @elp: error locator polynomial
36 * @poly_2t: temporary polynomials of degree 2t
37 */
38struct bch_control {
39 unsigned int m;
40 unsigned int n;
41 unsigned int t;
42 unsigned int ecc_bits;
43 unsigned int ecc_bytes;
44/* private: */
45 uint16_t *a_pow_tab;
46 uint16_t *a_log_tab;
47 uint32_t *mod8_tab;
48 uint32_t *ecc_buf;
49 uint32_t *ecc_buf2;
50 unsigned int *xi_tab;
51 unsigned int *syn;
52 int *cache;
53 struct gf_poly *elp;
54 struct gf_poly *poly_2t[4];
55};
56
57struct bch_control *init_bch(int m, int t, unsigned int prim_poly);
58
59void free_bch(struct bch_control *bch);
60
61void encode_bch(struct bch_control *bch, const uint8_t *data,
62 unsigned int len, uint8_t *ecc);
63
64int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
65 const uint8_t *recv_ecc, const uint8_t *calc_ecc,
66 const unsigned int *syn, unsigned int *errloc);
67
68#endif /* _BCH_H */