added comments to better explain physical and logical types

Signed-off-by: Alessandro Comodi <[email protected]>

Author: acomodi

libs/libarchfpga/src/physical_types.h

@@ -10,7 +10,8 @@
  * The data structures that store the
  *
  * Key data types:
- * t_logical_block_type: describes a placeable complex logic block,
+ * t_physical_tile_type: represents the type of a tile in the device grid and describes its physical characteristics (pin locations, area, width, height, etc.)
+ * t_logical_block_type: represents and describes the type of a clustered block
  * pb_type: describes the types of physical blocks within the t_logical_block_type in a hierarchy where the top block is the complex block and the leaf blocks implement one logical block
  * pb_graph_node: is a flattened version of pb_type so a pb_type with 10 instances will have 10 pb_graph_nodes representing each instance
  *
@@ -573,10 +574,6 @@ typedef const t_logical_block_type* t_logical_block_type_ptr;
  *                        Note that the SB is located to the top-right of the
  *                        grid tile location. [0..width-1][0..height-1]
  *
- *
- * pb_type: Internal subblocks and routing information for this physical block
- * pb_graph_head: Head of DAG of pb_types_nodes and their edges
- *
  * area: Describes how much area this logic block takes, if undefined, use default
  * type_timing_inf: timing information unique to this type
  * num_drivers: Total number of output drivers supplied

vpr/src/util/vpr_utils.cpp

@@ -643,6 +643,9 @@ bool is_empty_type(t_physical_tile_type_ptr type) {
 t_physical_tile_type_ptr physical_tile_type(t_logical_block_type_ptr logical_block_type) {
     auto& device_ctx = g_vpr_ctx.device();
 
+    /* It is assumed that there is a 1:1 mapping between logical and physical types
+     * making it possible to use the same index to access the corresponding type
+     */
     return &device_ctx.physical_tile_types[logical_block_type->index];
 }
 
@@ -657,6 +660,9 @@ t_physical_tile_type_ptr physical_tile_type(ClusterBlockId blk) {
 t_logical_block_type_ptr logical_block_type(t_physical_tile_type_ptr physical_tile_type) {
     auto& device_ctx = g_vpr_ctx.device();
 
+    /* It is assumed that there is a 1:1 mapping between logical and physical types
+     * making it possible to use the same index to access the corresponding type
+     */
     return &device_ctx.logical_block_types[physical_tile_type->index];
 }