encodehelpers.c

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

#include "encodehelpers.h"
#define DBG_LVL 4

/**************************
* multiply a vector with  *
* a specified part of H   *
* using the sparseness of *
* the graph               *
**************************/
void graphmultiply(graphs *graph, int rowstart, int rowend,
                   int colstart, int colend,
                   int *in, int *out) {
  int node, socket;

  for (node=rowstart; node<rowend; node++) {
    for (socket=0; socket<cnodedegree; socket++) {
      if ((cnodeedge.dest>=colstart) && (cnodeedge.dest<colend))
        out[node-rowstart]^=in[cnodeedge.dest-colstart];
    }
  }
}

/********************************
* perform a multiplication      *
* with T^-1 without explicitly  *
* computing T^-1 using the fact *
* that T is lower triangular    *
* and sparse                    *
********************************/
void multiplybytminusone(graphs *graph, int gap, int *in, int *out) {
  int node, socket;
  int vnodenum, cnodenum;
  int temp;

  vnodenum=(*graph).vnodenum;
  cnodenum=(*graph).cnodenum;

  for (node=0; node<(cnodenum-gap); node++) {
    temp=0;
    for (socket=0; socket<cnodedegree; socket++) {
      if ((cnodeedge.dest-vnodenum+cnodenum-gap)>=0)
        temp^=out[cnodeedge.dest-vnodenum+cnodenum-gap];
    }

    out[node]=(temp^in[node]);
  }
}


/******************
*  clear an array *
******************/
void cleararray (int *array, int length) {
  int i;
  for (i=0; i<length; i++)
    array[i]=0;
}

/******************
*  print a matrix *
******************/
void printmatrix (int *matrix, int gap, int vnodenum) {
  int row, col;
  for (row=0; row<gap; row++) {
    for (col=0; col<vnodenum; col++)
      PR_DBG_CL( 4,"%1d", *(matrix+row*vnodenum+col));
    PR_DBG_CL( 4,"\n");
  }
  PR_DBG_CL( 4,"\n");
}