rsdecodeiterate.m

该程序是RS编译码器的MATLAB仿真程序

%*************************************************************************
%   Copyright (C) 2008 Circuit and System Lab of PKU
%
%   Created     :   2008-5
%   Author      :   houdong([e-mail])
%
%   File Name   :   RsDecodeIterate.m
%
%   Abstract    :   Calculating the error locator polynomial
%                   
%   Version     :   1.0     2008-5   All Right Reserved.
%*************************************************************************
function [ErrorPosPolyCalc,SigmaCalc]=RsDecodeIterate(SyndromCalc)
%sigma(i:)是第i次叠带产生的错误位置多项式,step(i)表示第i次叠带产生的错误位置多项式的阶数,high是pi(x)第i+1次叠带的最高项系数
sigma=zeros(6,5);
step=zeros(1,6);
high=zeros(1,6);
sigma(1,1)=1;
step(1)=0;
high(1)=1;
sigma(2,1)=1;
step(2)=0;
high(2)=SyndromCalc(1);

% Massey Algorithm
for j=2:5
    if (high(j)==0)
        sigma(j+1,:)=sigma(j,:);
        step(j+1)=step(j);
    else
        for n=1:j-1
            if(high(n)~=0)
                i=n;
            end;
        end;
        temp=zeros(1,j-i+1);
        temp(j-i+1)=1;
        temp1=RsPolyMul(temp,sigma(i,:));
        len=length(temp1);
        temp2=zeros(1,5);
        temp2=temp1(1:5);
        sigma(j+1,:)=sigma(j,:)+high(j)*RsSymbolRev(high(i))*temp2;
        temp4=RsSymbolMul(high(j),RsSymbolRev(high(i)));
        for l=1:5
            sigma(j+1,l)=RsSymbolAdd(sigma(j,l),RsSymbolMul(temp4,temp2(l)));
        end;
    end;
        for m=1:5
            if (sigma(j+1,m)~=0)
                step(j+1)=m-1;
            end;
        end;
        for t=1:step(j+1)
            temp3=RsSymbolMul(sigma(j+1,t+1),SyndromCalc(j-t));
            high(j+1)=RsSymbolAdd(high(j+1),temp3);
        end;
        
        if(j<5)
        high(j+1)=RsSymbolAdd(high(j+1),SyndromCalc(j));
        end;
end;
SigmaCalc=sigma;
ErrorPosPolyCalc=sigma(6,:);