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 */ 80