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