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https://github.com/outbackdingo/UltraGrid.git
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a62fe80c3f
Corrected various spelling mistakes in comments, documentation, and variable names across the project. Changes include: - Documentation files (CONTRIBUTING.md, README.md, etc.) - Source code comments in C/C++ files - Function parameter names and descriptions No functional changes were made.
114 lines
2.6 KiB
C++
114 lines
2.6 KiB
C++
/*
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* =====================================================================================
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*
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* Filename: ldpc-matrix.c
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*
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* Description: Generates LDPC Staircase matrix
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*
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* Version: 1.0
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* Created: 04/14/2012 10:50:43 PM
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* Revision: none
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* Compiler: gcc
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*
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* Author: Milan Kabat (), kabat@ics.muni.cz
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* Company: FI MUNI
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*
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* =====================================================================================
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*/
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#include <time.h>
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#include <stdlib.h>
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#include "ldpc-matrix.h"
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#include "rand_pmms.h"
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/* Computes degree of a given row of the given matrix */
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int degree_of_row ( char **matrix, int row, int column_num )
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{
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int j = 0;
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int deg = 0;
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for ( j = 0; j < column_num; j++ )
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if ( matrix[row][j] )
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deg++;
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return deg;
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}
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void left_matrix_init ( char **matrix, int k, int n, int N1, int seed )
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{
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int i; /* Row index */
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int j; /* Column index */
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int h; /* Temporary variable */
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int t; /* Left limit within the list of possible choices u[] */
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int u[3*LDGM_MAX_K]; /* A table used to have a homogeneous 1 distribution. */
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Rand_pmms rand_gen;
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rand_gen.seedi(seed);
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for ( h = N1*k - 1; h >= 0; h--)
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{
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u[h] = h % (n-k);
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}
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/* Initialize the matrix with N1 "1s" per column, homogeneously */
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t = 0;
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for ( j = 0; j < k; j++ ) /* for each source symbol column */
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{
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for ( h = 0; h < N1; h++ ) /* put N1 "1s" */
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{
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/* Check whether valid available choices remain */
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for ( i = t; i < N1*k && matrix [u[i]] [j] ; i++);
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if ( i < N1*k )
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{
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/* Choose one index from possible choices */
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do {
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i = t + rand_gen.pmms_rand ( N1*k - t);
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} while ( matrix [u[i]] [j]);
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matrix [u[i]] [j] = 1;
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/* Replace with u[t] */
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u[i] = u[t];
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t++;
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} else {
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/* No available choices, pick at random */
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do {
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i = rand_gen.pmms_rand ( n-k );
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} while ( matrix[i][j] );
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matrix[i][j] = 1;
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}
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}
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}
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/* Add extra bits to avoid rows with less than two "1s". */
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for ( i = 0; i < n-k; i++ )
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{
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if ( degree_of_row ( matrix, i, k ) == 0 )
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{
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j = rand_gen.pmms_rand(k);
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matrix[i][j] = 1;
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}
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if ( degree_of_row ( matrix, i, k ) == 1 )
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{
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do {
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j = rand_gen.pmms_rand(k);
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} while ( matrix[i][j] );
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matrix[i][j] = 1;
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}
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}
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}
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void right_matrix_staircase_init ( char **matrix, int k, int n )
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{
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int i;
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matrix[0][k] = 1;
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for ( i = 1; i < n-k; i++)
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{
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matrix[i][k+i] = 1;
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matrix[i][k+i-1] = 1;
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}
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}
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