LXR linux/include/linux/bch.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   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 * @swap_bits:  swap bits within data and syndrome bytes
  37 */
  38struct 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        bool            swap_bits;
  56};
  57
  58struct bch_control *bch_init(int m, int t, unsigned int prim_poly,
  59                             bool swap_bits);
  60
  61void bch_free(struct bch_control *bch);
  62
  63void bch_encode(struct bch_control *bch, const uint8_t *data,
  64                unsigned int len, uint8_t *ecc);
  65
  66int bch_decode(struct bch_control *bch, const uint8_t *data, unsigned int len,
  67               const uint8_t *recv_ecc, const uint8_t *calc_ecc,
  68               const unsigned int *syn, unsigned int *errloc);
  69
  70#endif /* _BCH_H */
  71