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
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