short --> char for layer getter methods

Author: soheilshahrouz

libs/librrgraph/src/base/rr_graph_storage.h

@@ -1107,12 +1107,12 @@ class t_rr_graph_view {
     }
 
     /// @brief Retrieve the lowest layer (die) number where the given RRNodeId is located.
-    short node_layer_low(RRNodeId id) const {
+    char node_layer_low(RRNodeId id) const {
         return node_layer_low_[id];
     }
 
     /// @brief Retrieve the highest layer (die) number where the given RRNodeId is located.
-    short node_layer_high(RRNodeId id) const {
+    char node_layer_high(RRNodeId id) const {
         return node_layer_high_[id];
     }
 

libs/librrgraph/src/base/rr_graph_view.h

@@ -229,12 +229,12 @@ class RRGraphView {
     }
 
     /// @brief Returns the highest layer where a node is located at.
-    inline short node_layer_high(RRNodeId node) const {
+    inline char node_layer_high(RRNodeId node) const {
         return node_storage_.node_layer_high(node);
     }
 
     /// @brief Returns the lowest layer where a node is located at.
-    inline short node_layer_low(RRNodeId node) const {
+    inline char node_layer_low(RRNodeId node) const {
         return node_storage_.node_layer_low(node);
     }
 

libs/librrgraph/src/io/rr_graph_uxsdcxx_serializer.h

@@ -744,15 +744,18 @@ class RrGraphSerializer final : public uxsd::RrGraphBase<RrGraphContextTypes> {
         auto node = (*rr_nodes_)[inode];
         RRNodeId node_id = node.id();
 
-        VTR_ASSERT(layer_num >= 0);
+        // Currently, we only support two layers
+        VTR_ASSERT(layer_num >= 0 && layer_num <= 1);
         rr_graph_builder_->set_node_layer_low(node_id, layer_num);
     }
 
     inline void set_node_loc_layer_high(int layer_num, int& inode) final {
         auto node = (*rr_nodes_)[inode];
         RRNodeId node_id = node.id();
 
-        VTR_ASSERT(layer_num >= 0);
+        // Currently, we only support two layers
+        VTR_ASSERT(layer_num >= 0 && layer_num <= 1);
+        VTR_ASSERT(layer_num >= 0 && layer_num <= 1);
         rr_graph_builder_->set_node_layer_high(node_id, layer_num);
     }