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/* file: Depuncture.c
Description: Depuncture bits by zero-padding deleted bits.
The calling syntax is:
[output] = Depuncture(input, pun_pattern, tail_pattern )
output = Unpunctured codeword
input = Punctured codeword
pun_pattern = Puncturing pattern for encoded data bits
tail_pattern = Puncturing pattern for encoded tail bits
Copyright (C) 2005-2008, Matthew C. Valenti
Last updated on May 22, 2008
Function Depuncture 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>
/* Input Arguments
prhs[0] is input
prhs[1] is pun_pattern
prhs[2] is tail_pattern */
/* Output Arguments
plhs[0] is output */
/* main function that interfaces with MATLAB */
void mexFunction(
int nlhs,
mxArray *plhs[],
int nrhs,
const mxArray *prhs[] )
{
double *input, *pun_pattern, *tail_pattern; /* inputs */
double *output_p; /* output */
int height; /* height of input matrices */
int pun_period; /* period of puncturing pattern */
int tail_period; /* period of tail */
int pun_bits_per_frame;
int unpun_bits_per_frame;
int pun_bits_in_tail;
int unpun_bits_in_tail;
int pun_bits_in_payload;
int unpun_bits_in_payload;
int pun_bits_per_period;
int unpun_bits_per_period;
int number_pun_periods; /* number of puncture periods */
int partial_period = 0; /* length of last period (if partial) */
int number_fractional_bits;
int temp_count;
int i, j, count_punctured; /* counting variables */
/* Check for proper number of arguments */
if ((nrhs < 3 )||(nlhs > 1)) {
mexErrMsgTxt("Usage: [output] = Puncture(input, pun_pattern, tail_pattern )");
} else {
/* first input is the punctured word */
input = mxGetPr(prhs[0]);
pun_bits_per_frame = mxGetN(prhs[0]);
if ( mxGetM(prhs[0]) != 1 )
mexErrMsgTxt("Input must be a row vector");
/* second input is the puncturing pattern for coded data bits */
pun_pattern = mxGetPr(prhs[1]);
pun_period = mxGetN(prhs[1]);
height = mxGetM(prhs[1]);
unpun_bits_per_period = height*pun_period; /* number of unpunctured bits per payload period */
/* third input is the puncturing pattern for coded tail bits */
tail_pattern = mxGetPr(prhs[2]);
tail_period = mxGetN(prhs[2]);
if ( ( mxGetM(prhs[2])!=height )&&( tail_period > 0 ) )
mexErrMsgTxt("Number rows in tail_pattern must match the number in pun_pattern");
unpun_bits_in_tail = height*tail_period; /* number of unpunctured bits in the tail */
/* printf( "Height = %d\n", height );
printf( "Puncture Period = %d\n", pun_period );
printf( "Tail Period = %d\n", tail_period ); */
/* determine number of punctured bits per payload period (non-tail) */
pun_bits_per_period = 0;
for (i=0;i<pun_period*height;i++)
pun_bits_per_period += (int) pun_pattern[i];
/* printf( "Punctured bits per payload period = %d\n", pun_bits_per_period ); */
/* determine number of punctured bits in the tail */
pun_bits_in_tail = 0;
for (i=0;i<tail_period*height;i++)
pun_bits_in_tail += (int) tail_pattern[i];
/* printf( "Punctured bits in the tail = %d\n", pun_bits_in_tail ); */
/* determine how many periods in payload */
pun_bits_in_payload = pun_bits_per_frame - pun_bits_in_tail;
number_pun_periods = floor( pun_bits_in_payload/pun_bits_per_period );
/* printf( "Number Puncture Periods = %d\n", number_pun_periods ); */
/* determine if there is a fractional period in payload */
number_fractional_bits = pun_bits_in_payload - number_pun_periods*pun_bits_per_period;
/* printf( "Number of punctured fractional bits = %d\n", number_fractional_bits ); */
if (number_fractional_bits > 0 ) {
temp_count = 0;
i = 0; /* column */
while (temp_count < number_fractional_bits ) {
for (j = 0; j<height; j++ ) { /* row */
temp_count += pun_pattern[i*height+j];
}
if ( temp_count > number_fractional_bits )
mexErrMsgTxt( "Incomplete column of puncturing pattern" );
i++;
partial_period = i;
}
}
/* printf( "Length of Partial Period = %d\n", partial_period ); */
unpun_bits_in_payload = unpun_bits_per_period*number_pun_periods + height*partial_period;
unpun_bits_per_frame = unpun_bits_in_payload + unpun_bits_in_tail;
/* printf( "Number of Unpunctured Bits = %d\n", unpun_bits_per_frame ); */
/* set up output */
plhs[0] = mxCreateDoubleMatrix(height, unpun_bits_per_frame/height, mxREAL );
output_p = mxGetPr(plhs[0]);
/* unpuncture the coded data bits */
count_punctured = 0;
for (j=0;j<number_pun_periods;j++) { /* go through each period */
for (i=0;i<height*pun_period;i++) {
temp_count = pun_pattern[i];
while (temp_count > 0) {
output_p[j*pun_period*height+i]+=input[count_punctured];
count_punctured++;
temp_count--;
}
}
}
if (partial_period > 0) { /* go through last (partial) period */
for (i=0;i<height*partial_period;i++) {
temp_count = pun_pattern[i];
while (temp_count > 0) {
output_p[number_pun_periods*pun_period*height+i]+=input[count_punctured];
count_punctured++;
temp_count--;
}
}
}
/* depuncture the coded tail bits
New 11/21/05: if height = 4, then
the tail bits are rearranged to conform to UMTS convention */
if ( height == 4 ) {
/* upper RSC's tail bits */
for (i=0;i<tail_period;i++) {
for (j=0;j<2;j++) {
temp_count = tail_pattern[i*4+j];
while( temp_count > 0 ) {
output_p[unpun_bits_in_payload + i*4+j] += input[count_punctured];
count_punctured++;
temp_count--;
}
}
}
/* lower RSC's tail bits */
for (i=0;i<tail_period;i++) {
for (j=0;j<2;j++) {
temp_count = tail_pattern[i*4+j+2];
while( temp_count > 0 ) {
output_p[unpun_bits_in_payload + i*4+j+2] += input[count_punctured];
count_punctured++;
temp_count--;
}
}
}
} else {
for (i=0;i<unpun_bits_in_tail;i++) {
temp_count = tail_pattern[i];
while( temp_count > 0 ) {
output_p[unpun_bits_in_payload + i] += input[count_punctured];
count_punctured++;
temp_count--;
}
}
}
}
return;
}
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