linux/include/linux/bch.h
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   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 */
  49struct 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
  68struct bch_control *init_bch(int m, int t, unsigned int prim_poly);
  69
  70void free_bch(struct bch_control *bch);
  71
  72void encode_bch(struct bch_control *bch, const uint8_t *data,
  73                unsigned int len, uint8_t *ecc);
  74
  75int 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
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