functionnode.c

根据LDPC码中码子的构造方法中的PEG算法

#include "FunctionNode.h"
#include "VariableNode.h"
#include "Constant.h"
//#define EPS 1e-20

FunctionNode::FunctionNode(const char *name, int id, int numNeighbours, LocalFunction *localFunction) :
  Node(name, id, numNeighbours) {
  (*this).localFunction=localFunction;
}

void FunctionNode::update(int port) {
  
  double sum;

  //Brut Force implementation of update  
  //for every value in the alphabet of outgoing message
  for (int i=0; i<(*(VariableNode*)neighbours[port]).getSize(); i++){
    int *tempConfiguration = new int[numNeighbours];
    
    //reset tempConfiguration
    for (int k=0; k<numNeighbours; k++)
      tempConfiguration[k] = 0;
    sum = 0.0;
    summation(0, tempConfiguration, port, i, sum);
    outMessages[port][i] = sum;
    delete tempConfiguration;
  }
  
  //normalization of message values
  sum=0.0;
  for (i = 0; i < (*(VariableNode*)neighbours[port]).getSize(); i++) {
    sum +=outMessages[port][i];
  }
  for (i = 0; i < (*(VariableNode*)neighbours[port]).getSize(); i++) {
    if (sum > EPS) {
      outMessages[port][i] /=sum;
    } else {
      outMessages[port][i] = 1.0/(*(VariableNode*)neighbours[port]).getSize();
    }
  }
}
void FunctionNode::summation(int neighbourIndex, int *tempConfiguration, int fixVariableIndex, int fixVariableValue, double& sum){
  if (neighbourIndex < numNeighbours - 1) {
    for (int i=0; i < (*(VariableNode*)neighbours[neighbourIndex]).getSize(); i++) {
      tempConfiguration[neighbourIndex] = i;
      summation(neighbourIndex + 1, tempConfiguration, fixVariableIndex, fixVariableValue, sum);
    }
  }else {
    //for every configuration calculate a partial sum
    double tempProduct;
    for (int k = 0; k < (*(VariableNode*)neighbours[neighbourIndex]).getSize(); k++) {
      tempConfiguration[neighbourIndex] = k;
      tempConfiguration[fixVariableIndex] = fixVariableValue;
      tempProduct = 1.0;
      //multiply all incomming messages for this configuration
      for (int l=0; l<numNeighbours; l++){
	if (numNeighbours != fixVariableIndex)
	  tempProduct *= (*neighbours[l]).getOutMessage(portNumbers[l])[tempConfiguration[l]];
      }
      //and then multiply the messages with the local function
      tempProduct *= (*localFunction).getResult(tempConfiguration, numNeighbours);
      //add this term to the total sum
      sum += tempProduct;
    }
  }
}    



void FunctionNode::reset(void) {
  for (int n = 0; n < numNeighbours; n++) {
    int size = (*(VariableNode*)(neighbours[n])).getSize();
    for (int i = 0; i < size; i++) {
      outMessages[n][i] = 0.0;  //   1.0/size;
    }
  }
}

void FunctionNode::draw(void) {
  printf("NODE: %20s, %6d\n", name, id);
  printf("---------------------------------------------\n");
  printf("PORT      NEIGHBOUR                OUTMESSAGE\n");
  for (int n = 0; n < numNeighbours; n++) {
    printf("%3d       %20s%15f\n", n, (*neighbours[n]).getName(), outMessages[n][0]);
    int size = (*(VariableNode*)(neighbours[n])).getSize();
    for (int i = 1; i < size; i++) {
      printf("%45f\n", outMessages[n][i]);
    }
  }
  printf("\n");
}

void FunctionNode::draw(FILE *file) {
  fprintf(file, "NODE: %20s, %6d\n", name, id);
  fprintf(file, "---------------------------------------------\n");
  fprintf(file, "PORT      NEIGHBOUR                OUTMESSAGE\n");
  for (int n = 0; n < numNeighbours; n++) {
    fprintf(file, "%3d       %20s%15f\n", n, (*neighbours[n]).getName(), outMessages[n][0]);
    int size = (*(VariableNode*)(neighbours[n])).getSize();
    for (int i = 1; i < size; i++) {
      fprintf(file, "%45f\n", outMessages[n][i]);
    }
  }
  fprintf(file, "\n");
}