Package org.yamcs.rs

Class ReedSolomon

java.lang.Object

org.yamcs.rs.ReedSolomon

public class ReedSolomon
extends Object

Reed-Solomon encoder/decoder. Works with up to 7 bits per symbol (due to the byte in Java being signed)

Constructor Summary

Constructors

Constructor	Description
ReedSolomon(int nroots, int symsize, int fcr, int prim, int gfpoly, int pad)	Constructs a new encoder/decoder.

Method Summary

Modifier and Type	Method	Description
int	decode(byte[] data, int[] eras_pos)	Corrects in place data and returns the number of error corrected.
void	encode(byte[] data, byte[] parity)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReedSolomon

public ReedSolomon(int nroots,
                   int symsize,
                   int fcr,
                   int prim,
                   int gfpoly,
                   int pad)

Constructs a new encoder/decoder.

Parameters:

nroots - the number of roots in the Reed Solomon code generator polynomial. This equals the number of parity symbols per code block.

symsize - the symbol size in bits, up to 8

fcr - in index form, the first consecutive root of the Reed Solomon code generator polynomial.

prim - in index form, the primitive element in the Galois field used to generate the Reed Solomon code generator polynomial.

gfpoly - the extended Galois field generator polynomial coefficients, with the 0th coefficient in the low order bit. The polynomial must be primitive; if not, an IllegalArgumentException will be thrown.

pad - the number of leading symbols in the codeword that are implicitly padded to zero in a shortened code block

Method Detail

encode

public void encode(byte[] data,
                   byte[] parity)

decode

public int decode(byte[] data,
                  int[] eras_pos)
           throws ReedSolomonException

Corrects in place data and returns the number of error corrected.

Parameters:

data - - data to be corrected

eras_pos - - erasures positions (can be null)

Returns:

Throws:

ReedSolomonException - - thrown if the data cannot be corrected