Code snippet from Node.v that constructs a node's distance matrix.

Node_MatrixUpdateSnipper.v

for (r=0; r<NumNodes; r=r+1) begin
  for (c=0; c<NumNodes; c=c+1) begin
    if (r == NodeID) begin
      // this is our row in the distance matrix.
      // we use the adjacency vector to update the matrix. 
      if (c == NodeID) begin
        // the distance from a node to itself is 0
        dist_matrix_lcl[r][`NODE_SEL(c)] <= 0;                    
      end else if (adj_vec[c]) begin
        // the distance from a node to its neighbor is 1
        dist_matrix_lcl[r][`NODE_SEL(c)] <= 1;
      end else begin
        // we assume that there is no path to nodes other 
        // than ourselves and our immediate neighbors;
        // the distance is infinite, 
        // but this is hardware so -1 will have to do.
        dist_matrix_lcl[r][`NODE_SEL(c)] <= -1;
      end                        
    end else if (adj_vec[r]) begin
      // this row belong to one of our neighbors
      // we use their distance vector information 
      // to update our distance matrix.
      if (dist_matrix_rmt[r][`NODE_SEL(c)] == -1) begin
        // our neighrbor doesn't have a path to node c, so we assume that we don't either
        dist_matrix_lcl[r][`NODE_SEL(c)] <= -1;    
      end else begin
        // our neighbor says it has a path to node c.
        // since our neighbor is 1 hop away we add one to whatever distance they report for node c
        dist_matrix_lcl[r][`NODE_SEL(c)] <= dist_matrix_rmt[r][`NODE_SEL(c)] + 1;
      end    
    end else begin
      // this row doesn't belong to us or one of our immediate neighbors
      // we keep this row blank (filled with infinite distances)
      dist_matrix_lcl[r] <= {DistVecWidth{1'b1}};
    end
  end
end