1 /* SPDX-License-Identifier: GPL-2.0 */ 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 */ 37 struct bch_control { 38 unsigned int m; 39 unsigned int n; 40 unsigned int t; 41 unsigned int ecc_bits; 42 unsigned int ecc_bytes; 43 /* private: */ 44 uint16_t *a_pow_tab; 45 uint16_t *a_log_tab; 46 uint32_t *mod8_tab; 47 uint32_t *ecc_buf; 48 uint32_t *ecc_buf2; 49 unsigned int *xi_tab; 50 unsigned int *syn; 51 int *cache; 52 struct gf_poly *elp; 53 struct gf_poly *poly_2t[4]; 54 }; 55 56 struct bch_control *init_bch(int m, int t, unsigned int prim_poly); 57 58 void free_bch(struct bch_control *bch); 59 60 void encode_bch(struct bch_control *bch, const uint8_t *data, 61 unsigned int len, uint8_t *ecc); 62 63 int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len, 64 const uint8_t *recv_ecc, const uint8_t *calc_ecc, 65 const unsigned int *syn, unsigned int *errloc); 66 67 #endif /* _BCH_H */ 68