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/* RateDematch reverses the basic HSDPA Rate Matching algorithm
The calling syntax is:
y = RateDematch( x, X_i, e_ini, e_plus, e_minus );
y = depunctured output (length X_i)
x = input consisting of received/punctured bits
X_i = length of the depunctured output
e_ini = parameter used by algorithm
e_plus = parameter used by algorithm
e_minus = parameter used by algorithm
Copyright (C) 2005, Matthew C. Valenti
Last updated on Dec. 3, 2005
Function RateDematch is part of the Iterative Solutions
Coded Modulation Library. The Iterative Solutions Coded Modulation
Library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License,
or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include <mex.h>
#include <Matrix.h>
#include <stdlib.h>
/* main function that interfaces with MATLAB */
void mexFunction(
int nlhs,
mxArray *plhs[],
int nrhs,
const mxArray *prhs[] )
{
double *input, *output_p;
int X_i, e_ini, e_plus, e_minus;
int m, e, index, input_length;
/* Check for proper number of arguments */
if ((nrhs < 5 )||(nlhs > 1)) {
mexErrMsgTxt("Usage: y = RateDematch( x, X_i, e_ini, e_plus, e_minus )");
}
/* first input vector that needs to have rate matching reversed */
input = mxGetPr( prhs[0] );
input_length = mxGetN( prhs[0] ); /* length of input */
/* remaining inputs (all ints) */
X_i = (int) *mxGetPr( prhs[1] );
e_ini = (int) *mxGetPr( prhs[2] );
e_plus = (int) *mxGetPr( prhs[3] );
e_minus = (int) *mxGetPr( prhs[4] );
/* verify that input length is correct
development note: eventually this could be replaced by a formula */
e = e_ini;
index = 1;
for (m=1;m<=X_i;m++) {
e -= e_minus;
if (e<=0)
e += e_plus;
else
index++;
}
index--;
if ( index != input_length )
mexErrMsgTxt("Input length is invalid");
/* Create output */
plhs[0] = mxCreateDoubleMatrix( 1, X_i, mxREAL );
output_p = mxGetPr( plhs[0] );
/* Dematch */
e = e_ini;
index = 1;
for (m=1;m<=X_i;m++) {
e -= e_minus;
if (e<=0) {
/* zero pad */
e += e_plus;
} else {
output_p[m-1] = input[index-1];
index++;
}
}
return;
}
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