www.pudn.com > communicationmatlab.rar > SIMRSDEC.C
/*============================================================================
* Syntax: [sys, x0, str, ts] = simrsdec(t, x, u, flag, n, k, t_err, tp, dim)
*SIMBCHDC SIMULINK S-function for R-S decode.
* The m-dile is designed to be used in a SIMULINK S-Function block.
* This function will decode the cyclic code using R-S decode method.
* Parameters: n -- length of code word.
* k -- length of message.
* t -- error-correction capability.
* tp-- list of all GF(2^M) elements. n=2^M-1.
*
* The output has length n+1, the last digit is the error signal err.
* A non-negative err indicates number of errors have been corrected.
* A nagative err indicates that more than t error have been found in
* in the code, the routine cannot correct such error.
*============================================================================
* Original designed by Wes Wang,
* Jun Wu, The Mathworks, Inc.
* Feb-07, 1996
*
* Copyright (c) 1996 by The MAthWorks, Inc.
* All Rights Reserved
* $Revision: 1.1 $ $Date: 1996/04/01 19:05:13 $
*============================================================================
*/
#define S_FUNCTION_NAME simrsdec
/* need to include simstruc.h for the definition of the SimStruct and
* its associated macro definitions.
*/
#include "simstruc.h"
#include "gflib.c"
#ifdef MATLAB_MEX_FILE
#include "mex.h" /* needed for declaration of mexErrMsgTxt */
#endif
#define NUM_ARGS 4 /* four additional input arguments */
#define N ssGetArg(S,0)
#define K ssGetArg(S,1)
#define P ssGetArg(S,2)
#define DIM ssGetArg(S,3)
/*elseif (flag == 0)
* if 2^dim-1 ~= n
* error('Reed-Solomon decode has illegal code word length')
* end;
* sys(1) = 0; % no continuous state
* sys(2) = k+1; % number of discrete state
* sys(3) = k + 1; % number of output, code word length plus one.
* sys(4) = n + 1; % number of input, message length.
* sys(5) = 0;
* sys(6) = 1; % direct through flag.
* sys(7) = 1; % one sample rate
* x0 = [];
* ts = [-1, 0];
*/
static void mdlInitializeSizes(S)
SimStruct *S;
{
int i, np;
int n = (int)mxGetPr(N)[0];
int k = (int)mxGetPr(K)[0];
int dim = (int)mxGetPr(DIM)[0];
np = 1;
for(i=0; i < dim; i++)
np = np*2;
if ( np-1 != n ){
#ifdef MATLAB_MEX_FILE
mexErrMsgTxt("Reed-Solomon decode has illegal code word length");
#endif
}
ssSetNumContStates( S, 0); /* no continuous states */
ssSetNumDiscStates( S, 0); /* number of discrete states */
ssSetNumOutputs( S, k+1); /* number of output, code word length plus 4one*/
ssSetNumInputs( S, n+1); /* number of inputs, message length*/
ssSetDirectFeedThrough( S, 1); /* direct feedthrough flag */
ssSetNumSampleTimes( S, 1); /* number of sample times */
ssSetNumInputArgs( S, NUM_ARGS); /* number of input arguments*/
ssSetNumRWork( S, 0);
ssSetNumIWork( S, (n-2*k+6*dim+20)*n+4*dim+k*(k-12)+28);
/* n ------------- *code
* (n+1)*dim ----- *pp
* k ------------- *msg
* n ------------- *ccode
* 1 ------------- *err
* (n-2*k+5*dim+18)*n
* +3*dim+k*(k-13)+27 --- Iwork for rscore()
*/
ssSetNumPWork( S, 0);
}
/*
* mdlInitializeConditions - initialize the states
* Initialize the states, Integers and real-numbers
*/
static void mdlInitializeConditions(x0, S)
double *x0;
SimStruct *S;
{
int i;
int n = (int)mxGetPr(N)[0];
int k = (int)mxGetPr(K)[0];
int dim = (int)mxGetPr(DIM)[0];
int *code, *pp, *Iwork;
int *msg, *ccode, *err;
code = ssGetIWork(S);
pp = ssGetIWork(S)+n;
msg = ssGetIWork(S)+n+(n+1)*dim;
ccode = ssGetIWork(S)+n+(n+1)*dim + k;
err = ssGetIWork(S)+2*n+(n+1)*dim + k;
Iwork = ssGetIWork(S)+2*n+(n+1)*dim + k + 1;
err[0] = 0;
for( i=0; i<(n+1)*dim; i++)
pp[i] = (int)mxGetPr(P)[i];
}
/*
* mdlInitializeSampleTimes - initialize the sample times array
*
* This function is used to specify the sample time(s) for your S-function.
* If your S-function is continuous, you must specify a sample time of 0.0.
* Sample times must be registered in ascending order.
*/
static void mdlInitializeSampleTimes(S)
SimStruct *S;
{
ssSetSampleTimeEvent(S, 0, 0.0);
ssSetOffsetTimeEvent(S, 0, 0.0);
}
/*if (flag == 3)
* % refresh the state only when there is a trigger signal
* len_u = length(u);
* if u(len_u)
* % output the decode result.
* % main calculation
* [sys, err] = rscore(u(1:len_u-1)-1, k, tp, dim, n);
* % output is the combination of message and error information.
* sys = sys +1;
* indx = find(~(sys>=0));
* sys(indx) = indx-indx;
* sys = [sys(:); err];
* end;
*/
/*
* mdlOutputs - compute the outputs
*
* In this function, you compute the outputs of your S-function
* block. The outputs are placed in the y variable.
*/
static void mdlOutputs(y, x, u, S, tid)
double *y, *x, *u;
SimStruct *S;
int tid;
{
int i;
int n = (int)mxGetPr(N)[0];
int k = (int)mxGetPr(K)[0];
int dim = (int)mxGetPr(DIM)[0];
int *code, *pp, *Iwork;
int *msg, *ccode, *err;
code = ssGetIWork(S);
pp = ssGetIWork(S)+n;
msg = ssGetIWork(S)+n+(n+1)*dim;
ccode = ssGetIWork(S)+n+(n+1)*dim + k;
err = ssGetIWork(S)+2*n+(n+1)*dim + k;
Iwork = ssGetIWork(S)+2*n+(n+1)*dim + k + 1;
if( u[n] != 0 ){
/* output the decode result.
* main calculation
* [sys, err] = rscore(u(1:len_u-1), n, dim, k, t_err, tp);
*/
for( i=0; i<(n+1)*dim; i++)
pp[i] = (int)mxGetPr(P)[i];
for( i=0; i