errlocp.c

经典通信系统仿真书籍《通信系统与 MATLAB (Proakis)》源代码

/*============================================================================
 *  Syntax: [sigma, err] = errlocp(syndrome, t, tp, pow_dim, err, type_flag)
 * ERRLOCP Computes the error-location polynomial.
 *       [SIGMA, ERR] = ERRLOCP(SYNDROME, T, TP, ERR, FLAG) computes the
 *       error-location polynomial from length 2*T input vector SYNDROME.
 *       T is the error-correction capability. Tp is the complete tuple list
 *       of all elements in GF(2^M). POW_DIM = 2^M-1, which is the dimension
 *       of GF(2^M).  ERR contains the error information in the computation.
 *       FLAG indicates the method to be used in the computation.
 *       FLAG = 1, uses normal method.
 *       FLAG = 0, use simplified method. The simplified method can be
 *                      used for binary code only. 
 *
 *       Warning: This function does not provide error-check. Make sure
 *                the parameters are signed correctly.
 *
 *============================================================================
 *     Jun Wu,     The Mathworks, Inc.
 *     Dec-10, 1995
 *
 *     Copyright (c) 1995-96 by The MAthWorks, Inc.
 *     All Rights Reserved
 *     $Revision: 1.1 $  $Date: 1996/04/01 18:13:51 $
 *==========================================================================
 */
#include <math.h>
#include "mex.h"
#include "gflib.c"
void mexFunction(int nlhs, Matrix *plhs[], int nrhs, Matrix *prhs[])
{
    int     i, t, np, mp, pow_dim, prim, Flag, err_In[1], len_Out[1];
    int     *syndr, *pp, *Iwork, *pNum, *pInv, *sigma_Out;
    double  *sigma, *errOut, *syndrome, *T, *p, *Pow_dim, *err, *flag;

    syndrome = mxGetPr(prhs[0]);
    T   = mxGetPr(prhs[1]);
    p   = mxGetPr(prhs[2]);
    Pow_dim = mxGetPr(prhs[3]);
    err = mxGetPr(prhs[4]);
    flag = mxGetPr(prhs[5]);

    np = mxGetM(prhs[2]);
    mp = mxGetN(prhs[2]);
    if ( nrhs < 6 || *T < 0 || *Pow_dim < np-1 || *err<0 || *flag<0 || mxGetM(prhs[0])*mxGetN(prhs[0])<2*(*T) ){
        mexErrMsgTxt("Not Correct Input Argument! Input again!");        
        return;
    }
    /* converting the type of variables to integer.*/
    t = (int)*T;
    Flag = (int)*flag;
    err_In[0] = (int)*err;
    pow_dim = (int)*Pow_dim;
    syndr = (int *)mxCalloc(2*t,sizeof(int));
    len_Out[0] = 0;
    for(i=0; i<2*t; i++)
        syndr[i] = (int) syndrome[i];
    pp = (int *)mxCalloc(np*mp,sizeof(int));
    for(i=0; i<np*mp; i++)
        pp[i] = (int) p[i];
    /* set up a integer working space (int *)Iwork for functions. */
    if( Flag ){
        t=2*t;
        Iwork = (int *)mxCalloc((2+mp)*np+5*(t+2)+(t+5)*(t+1), sizeof(int));
    } else {
        Iwork = (int *)mxCalloc((2+mp)*np+5*(t+2)+(t+5)*(t+1), sizeof(int));
    }
    pNum = Iwork;
    pInv = Iwork + np;
    prim = 2;
    pNumInv(pp, np, mp, prim, pNum, pInv, pInv+np);
    if ( Flag ){
        sigma_Out = Iwork+(2+mp)*np;
        errlocp1(syndr,t,pNum,pInv,pow_dim,err_In,sigma_Out+(t+1),sigma_Out,len_Out);
    }else{
        sigma_Out = Iwork+(2+mp)*np;
        errlocp0(syndr,t,pNum,pInv,pow_dim,err_In,sigma_Out+(t+1),sigma_Out,len_Out);
	}

    /* output parameters list */
    sigma = mxGetPr(plhs[0] = mxCreateFull(1, len_Out[0], 0));
    for(i=0; i < len_Out[0]; i++)
        sigma[i] = (double)sigma_Out[i];
    errOut = mxGetPr(plhs[1] = mxCreateFull(1, 1, 0));
    if ( err_In[0] != 0 )
        errOut[0] = 1;
    else
        errOut[0] = 0;
    return;
}
/*--end of errlocp.c--*/