1 /* 2 * Generic binary BCH encoding/decoding library 3 * 4 * SPDX-License-Identifier: GPL-2.0 5 * 6 * Copyright © 2011 Parrot S.A. 7 * 8 * Author: Ivan Djelic <ivan.djelic@parrot.com> 9 * 10 * Description: 11 * 12 * This library provides runtime configurable encoding/decoding of binary 13 * Bose-Chaudhuri-Hocquenghem (BCH) codes. 14 */ 15 #ifndef _BCH_H 16 #define _BCH_H 17 18 #include <linux/types.h> 19 20 /** 21 * struct bch_control - BCH control structure 22 * @m: Galois field order 23 * @n: maximum codeword size in bits (= 2^m-1) 24 * @t: error correction capability in bits 25 * @ecc_bits: ecc exact size in bits, i.e. generator polynomial degree (<=m*t) 26 * @ecc_bytes: ecc max size (m*t bits) in bytes 27 * @a_pow_tab: Galois field GF(2^m) exponentiation lookup table 28 * @a_log_tab: Galois field GF(2^m) log lookup table 29 * @mod8_tab: remainder generator polynomial lookup tables 30 * @ecc_buf: ecc parity words buffer 31 * @ecc_buf2: ecc parity words buffer 32 * @xi_tab: GF(2^m) base for solving degree 2 polynomial roots 33 * @syn: syndrome buffer 34 * @cache: log-based polynomial representation buffer 35 * @elp: error locator polynomial 36 * @poly_2t: temporary polynomials of degree 2t 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 }; 56 57 struct bch_control *init_bch(int m, int t, unsigned int prim_poly); 58 59 void free_bch(struct bch_control *bch); 60 61 void encode_bch(struct bch_control *bch, const uint8_t *data, 62 unsigned int len, uint8_t *ecc); 63 64 int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len, 65 const uint8_t *recv_ecc, const uint8_t *calc_ecc, 66 const unsigned int *syn, unsigned int *errloc); 67 68 #endif /* _BCH_H */ 69