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 | * @swap_bits: swap bits within data and syndrome bytes |
37 | */ |
38 | struct 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 | bool swap_bits; |
56 | }; |
57 | |
58 | struct bch_control *bch_init(int m, int t, unsigned int prim_poly, |
59 | bool swap_bits); |
60 | |
61 | void bch_free(struct bch_control *bch); |
62 | |
63 | void bch_encode(struct bch_control *bch, const uint8_t *data, |
64 | unsigned int len, uint8_t *ecc); |
65 | |
66 | int bch_decode(struct bch_control *bch, const uint8_t *data, unsigned int len, |
67 | const uint8_t *recv_ecc, const uint8_t *calc_ecc, |
68 | const unsigned int *syn, unsigned int *errloc); |
69 | |
70 | #endif /* _BCH_H */ |
71 | |