| 1 |
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| 2 | |
| 3 | * Generic binary BCH encoding/decoding library
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| 4 | *
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| 5 | * Copyright © 2011 Parrot S.A.
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| 6 | *
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| 7 | * Author: Ivan Djelic <[email protected]>
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| 8 | *
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| 9 | * Description:
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| 10 | *
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| 11 | * This library provides runtime configurable encoding/decoding of binary
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| 12 | * Bose-Chaudhuri-Hocquenghem (BCH) codes.
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| 13 |
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| 14 | #ifndef _BCH_H
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| 15 | #define _BCH_H
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| 16 |
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| 17 | #include <linux/types.h>
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| 18 |
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| 19 | |
| 20 | * struct bch_control - BCH control structure
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| 21 | * @m: Galois field order
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| 22 | * @n: maximum codeword size in bits (= 2^m-1)
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| 23 | * @t: error correction capability in bits
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| 24 | * @ecc_bits: ecc exact size in bits, i.e. generator polynomial degree (<=m*t)
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| 25 | * @ecc_bytes: ecc max size (m*t bits) in bytes
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| 26 | * @a_pow_tab: Galois field GF(2^m) exponentiation lookup table
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| 27 | * @a_log_tab: Galois field GF(2^m) log lookup table
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| 28 | * @mod8_tab: remainder generator polynomial lookup tables
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| 29 | * @ecc_buf: ecc parity words buffer
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| 30 | * @ecc_buf2: ecc parity words buffer
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| 31 | * @xi_tab: GF(2^m) base for solving degree 2 polynomial roots
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| 32 | * @syn: syndrome buffer
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| 33 | * @cache: log-based polynomial representation buffer
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| 34 | * @elp: error locator polynomial
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| 35 | * @poly_2t: temporary polynomials of degree 2t
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| 36 | * @swap_bits: swap bits within data and syndrome bytes
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| 37 |
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| 38 | struct bch_control {
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| 39 | unsigned int m;
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| 40 | unsigned int n;
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| 41 | unsigned int t;
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| 42 | unsigned int ecc_bits;
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| 43 | unsigned int ecc_bytes;
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| 44 |
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| 45 | uint16_t *a_pow_tab;
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| 46 | uint16_t *a_log_tab;
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| 47 | uint32_t *mod8_tab;
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| 48 | uint32_t *ecc_buf;
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| 49 | uint32_t *ecc_buf2;
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| 50 | unsigned int *xi_tab;
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| 51 | unsigned int *syn;
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| 52 | int *cache;
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| 53 | struct gf_poly *elp;
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| 54 | struct gf_poly *poly_2t[4];
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| 55 | bool swap_bits;
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| 56 | };
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| 57 |
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| 58 | struct bch_control *bch_init(int m, int t, unsigned int prim_poly,
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| 59 | bool swap_bits);
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| 60 |
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| 61 | void bch_free(struct bch_control *bch);
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| 62 |
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| 63 | void bch_encode(struct bch_control *bch, const uint8_t *data,
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| 64 | unsigned int len, uint8_t *ecc);
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| 65 |
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| 66 | int bch_decode(struct bch_control *bch, const uint8_t *data, unsigned int len,
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| 67 | const uint8_t *recv_ecc, const uint8_t *calc_ecc,
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| 68 | const unsigned int *syn, unsigned int *errloc);
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| 69 |
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| 70 | #endif
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