/*
   * Generic binary BCH encoding/decoding library
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Copyright © 2011 Parrot S.A.
   *
   * Author: Ivan Djelic <ivan.djelic@parrot.com>
   *
   * Description:
   *
   * This library provides runtime configurable encoding/decoding of binary
   * Bose-Chaudhuri-Hocquenghem (BCH) codes.
  */
  #ifndef _BCH_H
  #define _BCH_H
  
  #include <linux/types.h>
  
  /**
   * struct bch_control - BCH control structure
   * @m:          Galois field order
   * @n:          maximum codeword size in bits (= 2^m-1)
   * @t:          error correction capability in bits
   * @ecc_bits:   ecc exact size in bits, i.e. generator polynomial degree (<=m*t)
   * @ecc_bytes:  ecc max size (m*t bits) in bytes
   * @a_pow_tab:  Galois field GF(2^m) exponentiation lookup table
   * @a_log_tab:  Galois field GF(2^m) log lookup table
   * @mod8_tab:   remainder generator polynomial lookup tables
   * @ecc_buf:    ecc parity words buffer
   * @ecc_buf2:   ecc parity words buffer
   * @xi_tab:     GF(2^m) base for solving degree 2 polynomial roots
   * @syn:        syndrome buffer
   * @cache:      log-based polynomial representation buffer
   * @elp:        error locator polynomial
   * @poly_2t:    temporary polynomials of degree 2t
   */
  struct bch_control {
  	unsigned int    m;
  	unsigned int    n;
  	unsigned int    t;
  	unsigned int    ecc_bits;
  	unsigned int    ecc_bytes;
  /* private: */
  	uint16_t       *a_pow_tab;
  	uint16_t       *a_log_tab;
  	uint32_t       *mod8_tab;
  	uint32_t       *ecc_buf;
  	uint32_t       *ecc_buf2;
  	unsigned int   *xi_tab;
  	unsigned int   *syn;
  	int            *cache;
  	struct gf_poly *elp;
  	struct gf_poly *poly_2t[4];
  };
  
  struct bch_control *init_bch(int m, int t, unsigned int prim_poly);
  
  void free_bch(struct bch_control *bch);
  
  void encode_bch(struct bch_control *bch, const uint8_t *data,
  		unsigned int len, uint8_t *ecc);
  
  int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
  	       const uint8_t *recv_ecc, const uint8_t *calc_ecc,
  	       const unsigned int *syn, unsigned int *errloc);
  
  #endif /* _BCH_H */