include/linux/bch.h

   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 */