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");
   }