[vpr][place][net_cost] get_chanz_cost_factor impl

Author: amin1377

vpr/src/place/net_cost_handler.cpp

@@ -1604,6 +1604,32 @@ double NetCostHandler::get_net_wirelength_from_layer_bb_(ClusterNetId net_id) {
     return ncost;
 }
 
+float NetCostHandler::get_chanz_cost_factor(const t_bb& bounding_box, float place_cost_exp) {
+    int x_high = bounding_box.xmax;
+    int x_low = bounding_box.xmin;
+    int y_high = bounding_box.ymax;
+    int y_low = bounding_box.ymin;
+
+    int num_inter_dir_conn = acc_tile_num_inter_die_conn_[x_high][y_high] - \
+                            acc_tile_num_inter_die_conn_[x_low-1][y_high] - \
+                            acc_tile_num_inter_die_conn_[x_high][y_low-1] + \
+                            acc_tile_num_inter_die_conn_[x_low-1][y_low-1];
+    
+    int bb_num_tiles = (x_high - x_low + 1) * (y_high - y_low + 1);
+    
+    float z_cost_factor;
+    if (num_inter_dir_conn == 0) {
+        return 1.0f;
+    } else {
+        z_cost_factor = bb_num_tiles / static_cast<float>(num_inter_dir_conn);
+        z_cost_factor = pow((double)z_cost_factor, (double)place_cost_exp);
+
+    }
+
+    return z_cost_factor;
+
+}
+
 double NetCostHandler::recompute_bb_cost_() {
     double cost = 0;
 

vpr/src/place/net_cost_handler.h

@@ -201,7 +201,7 @@ class NetCostHandler {
       * but applies to the height of the bounding box. The chanZ factor is calculated during block placement because storing it in the 
       * same way as the X and Y cost factors would require a 4D array and population it is an O(n^2) operation.
      */
-    vtr::NdMatrix<float, 2> acc_tile_num_inter_die_conn_;
+    vtr::NdMatrix<int, 2> acc_tile_num_inter_die_conn_;
 
 
   private:
@@ -519,6 +519,6 @@ class NetCostHandler {
      * @param bounding_box Bounding box of the net which chanz cost factor is to be calculated
      * @return ChanZ cost factor
      */
-    float get_chanz_cost_factor(const t_bb& bounding_box);
+    float get_chanz_cost_factor(const t_bb& bounding_box, float place_cost_exp);
 
 };