forked from KolibriOS/kolibrios
112 lines
4.0 KiB
C
112 lines
4.0 KiB
C
/*
|
|
* Copyright (c) 2001-2003, David Janssens
|
|
* Copyright (c) 2002-2003, Yannick Verschueren
|
|
* Copyright (c) 2003-2005, Francois Devaux and Antonin Descampe
|
|
* Copyright (c) 2005, Hervé Drolon, FreeImage Team
|
|
* Copyright (c) 2002-2005, Communications and remote sensing Laboratory, Universite catholique de Louvain, Belgium
|
|
* Copyright (c) 2005-2006, Dept. of Electronic and Information Engineering, Universita' degli Studi di Perugia, Italy
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#ifdef USE_JPWL
|
|
|
|
/**
|
|
@file rs.h
|
|
@brief Functions used to compute Reed-Solomon parity and check of byte arrays
|
|
|
|
*/
|
|
|
|
#ifndef __RS_HEADER__
|
|
#define __RS_HEADER__
|
|
|
|
/** Global definitions for Reed-Solomon encoder/decoder
|
|
* Phil Karn KA9Q, September 1996
|
|
*
|
|
* The parameters MM and KK specify the Reed-Solomon code parameters.
|
|
*
|
|
* Set MM to be the size of each code symbol in bits. The Reed-Solomon
|
|
* block size will then be NN = 2**M - 1 symbols. Supported values are
|
|
* defined in rs.c.
|
|
*
|
|
* Set KK to be the number of data symbols in each block, which must be
|
|
* less than the block size. The code will then be able to correct up
|
|
* to NN-KK erasures or (NN-KK)/2 errors, or combinations thereof with
|
|
* each error counting as two erasures.
|
|
*/
|
|
#define MM 8 /* RS code over GF(2**MM) - change to suit */
|
|
//static int KK;
|
|
int KK;
|
|
|
|
/* Original code */
|
|
/*#define KK 239*/ /* KK = number of information symbols */
|
|
|
|
#define NN ((1 << MM) - 1)
|
|
|
|
#if (MM <= 8)
|
|
typedef unsigned char dtype;
|
|
#else
|
|
typedef unsigned int dtype;
|
|
#endif
|
|
|
|
/** Initialization function */
|
|
void init_rs(int);
|
|
|
|
/** These two functions *must* be called in this order (e.g.,
|
|
* by init_rs()) before any encoding/decoding
|
|
*/
|
|
void generate_gf(void); /* Generate Galois Field */
|
|
void gen_poly(void); /* Generate generator polynomial */
|
|
|
|
/** Reed-Solomon encoding
|
|
* data[] is the input block, parity symbols are placed in bb[]
|
|
* bb[] may lie past the end of the data, e.g., for (255,223):
|
|
* encode_rs(&data[0],&data[223]);
|
|
*/
|
|
int encode_rs(dtype data[], dtype bb[]);
|
|
|
|
/** Reed-Solomon erasures-and-errors decoding
|
|
* The received block goes into data[], and a list of zero-origin
|
|
* erasure positions, if any, goes in eras_pos[] with a count in no_eras.
|
|
*
|
|
* The decoder corrects the symbols in place, if possible and returns
|
|
* the number of corrected symbols. If the codeword is illegal or
|
|
* uncorrectible, the data array is unchanged and -1 is returned
|
|
*/
|
|
int eras_dec_rs(dtype data[], int eras_pos[], int no_eras);
|
|
|
|
/**
|
|
Computes the minimum between two integers
|
|
@param a first integer to compare
|
|
@param b second integer to compare
|
|
@return returns the minimum integer between a and b
|
|
*/
|
|
#ifndef min
|
|
#define min(a,b) (((a) < (b)) ? (a) : (b))
|
|
#endif /* min */
|
|
|
|
#endif /* __RS_HEADER__ */
|
|
|
|
|
|
#endif /* USE_JPWL */
|