| Ivan Djelic | 437aa56 | 2011-03-11 11:05:32 +0100 | [diff] [blame] | 1 | /* |
| 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 | */ |
| 49 | struct 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 | |
| 68 | struct bch_control *init_bch(int m, int t, unsigned int prim_poly); |
| 69 | |
| 70 | void free_bch(struct bch_control *bch); |
| 71 | |
| 72 | void encode_bch(struct bch_control *bch, const uint8_t *data, |
| 73 | unsigned int len, uint8_t *ecc); |
| 74 | |
| 75 | int 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 */ |