/********************************************************************
 * This file includes functions to print Verilog modules for a Grid
 * (CLBs, I/Os, heterogeneous blocks etc.) 
 *******************************************************************/
/* System header files */
#include <vector>
#include <fstream>

/* Header files from external libs */
#include "vtr_geometry.h"
#include "util.h"
#include "vtr_assert.h"
#include "circuit_library_utils.h"

/* Header files for VPR */
#include "vpr_types.h"
#include "globals.h"

/* Header files for FPGA X2P tool suite */
#include "fpga_x2p_naming.h"
#include "fpga_x2p_types.h"
#include "fpga_x2p_utils.h"
#include "fpga_x2p_pbtypes_utils.h"
#include "module_manager_utils.h"
#include "fpga_x2p_globals.h"

/* Header files for Verilog generator */
#include "verilog_global.h"
#include "verilog_utils.h"
#include "verilog_writer_utils.h"
#include "verilog_module_writer.h"
#include "verilog_grid.h"

/********************************************************************
 * Find the side where I/O pins locate on a grid I/O block
 * 1. I/O grids on the top    side of FPGA only have ports on its bottom side
 * 2. I/O grids on the right  side of FPGA only have ports on its left   side
 * 3. I/O grids on the bottom side of FPGA only have ports on its top    side
 * 4. I/O grids on the left   side of FPGA only have ports on its right side
 *******************************************************************/
static 
e_side find_grid_module_pin_side(t_type_ptr grid_type_descriptor,
                                 const e_side& border_side) {
  VTR_ASSERT(IO_TYPE == grid_type_descriptor);
  Side side_manager(border_side);
  return side_manager.get_opposite(); 
}

/********************************************************************
 * Add ports/pins to a grid module 
 * This function will iterate over all the pins that are defined 
 * in type_descripter and give a name by its height, side and index
 *
 * In particular, for I/O grid, only part of the ports on required
 * on a specific side.
 *******************************************************************/
static 
void add_grid_module_pb_type_ports(ModuleManager& module_manager,
                                   const ModuleId& grid_module,
                                   t_type_ptr grid_type_descriptor,
                                   const e_side& border_side) {
  /* Ensure that we have a valid grid_type_descriptor */
  VTR_ASSERT(NULL != grid_type_descriptor);

  /* Find the pin side for I/O grids*/
  std::vector<e_side> grid_pin_sides;
  /* For I/O grids, we care only one side
   * Otherwise, we will iterate all the 4 sides  
   */
  if (IO_TYPE == grid_type_descriptor) {
    grid_pin_sides.push_back(find_grid_module_pin_side(grid_type_descriptor, border_side));
  } else {
    grid_pin_sides.push_back(TOP); 
    grid_pin_sides.push_back(RIGHT); 
    grid_pin_sides.push_back(BOTTOM); 
    grid_pin_sides.push_back(LEFT); 
  }

  /* Create a map between pin class type and grid pin direction */
  std::map<e_pin_type, ModuleManager::e_module_port_type> pin_type2type_map;
  pin_type2type_map[RECEIVER] = ModuleManager::MODULE_INPUT_PORT;
  pin_type2type_map[DRIVER] = ModuleManager::MODULE_OUTPUT_PORT;

  /* Iterate over sides, height and pins */
  for (const e_side& side : grid_pin_sides) {
    for (int iheight = 0; iheight < grid_type_descriptor->height; ++iheight) {
      for (int ipin = 0; ipin < grid_type_descriptor->num_pins; ++ipin) {
        if (1 != grid_type_descriptor->pinloc[iheight][side][ipin]) {
          continue;
        }
        /* Reach here, it means this pin is on this side */
        int class_id = grid_type_descriptor->pin_class[ipin];
        e_pin_type pin_class_type = grid_type_descriptor->class_inf[class_id].type;
        /* Generate the pin name, 
         * we give a empty coordinate but it will not be used (see details in the function 
         */
        vtr::Point<size_t> dummy_coordinate;
        std::string port_name = generate_grid_port_name(dummy_coordinate, iheight, side, ipin, false);
        BasicPort grid_port(port_name, 0, 0);
        /* Add the port to the module */
        module_manager.add_port(grid_module, grid_port, pin_type2type_map[pin_class_type]);
      }  
    }
  }
}

/********************************************************************
 * Add module nets to connect a port of child pb_module
 * to the grid module 
 *******************************************************************/
static 
void add_grid_module_net_connect_pb_graph_pin(ModuleManager& module_manager,
                                              const ModuleId& grid_module,
                                              const ModuleId& child_module,
                                              const size_t& child_instance,
                                              t_type_ptr grid_type_descriptor,
                                              t_pb_graph_pin* pb_graph_pin,
                                              const e_side& border_side,
                                              const enum e_spice_pin2pin_interc_type& pin2pin_interc_type) {
  /* Find the pin side for I/O grids*/
  std::vector<e_side> grid_pin_sides;
  /* For I/O grids, we care only one side
   * Otherwise, we will iterate all the 4 sides  
   */
  if (IO_TYPE == grid_type_descriptor) {
    grid_pin_sides.push_back(find_grid_module_pin_side(grid_type_descriptor, border_side));
  } else {
    grid_pin_sides.push_back(TOP); 
    grid_pin_sides.push_back(RIGHT); 
    grid_pin_sides.push_back(BOTTOM); 
    grid_pin_sides.push_back(LEFT); 
  }

  /* num_pins/capacity = the number of pins that each type_descriptor has.
   * Capacity defines the number of type_descriptors in each grid
   * so the pin index at grid level = pin_index_in_type_descriptor 
   *                                + type_descriptor_index_in_capacity * num_pins_per_type_descriptor
   */
  size_t grid_pin_index = pb_graph_pin->pin_count_in_cluster 
                        + child_instance * grid_type_descriptor->num_pins / grid_type_descriptor->capacity;
  int pin_height = grid_type_descriptor->pin_height[grid_pin_index];
  for (const e_side& side : grid_pin_sides) {
    if (1 != grid_type_descriptor->pinloc[pin_height][side][grid_pin_index]) {
      continue;
    }
    /* Reach here, it means this pin is on this side */
    /* Create a net to connect the grid pin to child module pin */
    ModuleNetId net = module_manager.create_module_net(grid_module);
    /* Find the port in grid_module */
    vtr::Point<size_t> dummy_coordinate;
    std::string grid_port_name = generate_grid_port_name(dummy_coordinate, pin_height, side, grid_pin_index, false);
    ModulePortId grid_module_port_id = module_manager.find_module_port(grid_module, grid_port_name);
    VTR_ASSERT(true == module_manager.valid_module_port_id(grid_module, grid_module_port_id));
    /* Grid port always has only 1 pin, it is assumed when adding these ports to the module
     * if you need a change, please also change the port adding codes  
     */
    size_t grid_module_pin_id = 0;
    /* Find the port in child module */
    std::string child_module_port_name = generate_pb_type_port_name(pb_graph_pin->port);
    ModulePortId child_module_port_id = module_manager.find_module_port(child_module, child_module_port_name);
    VTR_ASSERT(true == module_manager.valid_module_port_id(child_module, child_module_port_id));
    size_t child_module_pin_id = pb_graph_pin->pin_number;
    /* Add net sources and sinks:
     * For input-to-input connection, net_source is grid pin, while net_sink is pb_graph_pin   
     * For output-to-output connection, net_source is pb_graph_pin, while net_sink is grid pin   
     */
    switch (pin2pin_interc_type) {
    case INPUT2INPUT_INTERC:
      module_manager.add_module_net_source(grid_module, net, grid_module, 0, grid_module_port_id, grid_module_pin_id);
      module_manager.add_module_net_sink(grid_module, net, child_module, child_instance, child_module_port_id, child_module_pin_id);
      break;
    case OUTPUT2OUTPUT_INTERC:
      module_manager.add_module_net_source(grid_module, net, child_module, child_instance, child_module_port_id, child_module_pin_id);
      module_manager.add_module_net_sink(grid_module, net, grid_module, 0, grid_module_port_id, grid_module_pin_id);
      break;
    default:
      vpr_printf(TIO_MESSAGE_ERROR,
                 "(File:%s, [LINE%d]) Invalid pin-to-pin interconnection type!\n",
                 __FILE__, __LINE__);
      exit(1);
    }
  }
}


/********************************************************************
 * Add module nets to connect ports/pins of a grid module 
 * to its child modules
 * This function will iterate over all the pins that are defined 
 * in type_descripter and find the corresponding pin in the top
 * pb_graph_node of the grid 
 *******************************************************************/
static 
void add_grid_module_nets_connect_pb_type_ports(ModuleManager& module_manager,
                                                const ModuleId& grid_module,
                                                const ModuleId& child_module,
                                                const size_t& child_instance,
                                                t_type_ptr grid_type_descriptor,
                                                const e_side& border_side) {
  /* Ensure that we have a valid grid_type_descriptor */
  VTR_ASSERT(NULL != grid_type_descriptor);
  t_pb_graph_node* top_pb_graph_node = grid_type_descriptor->pb_graph_head;
  VTR_ASSERT(NULL != top_pb_graph_node); 

  for (int iport = 0; iport < top_pb_graph_node->num_input_ports; ++iport) {
    for (int ipin = 0; ipin < top_pb_graph_node->num_input_pins[iport]; ++ipin) {
      add_grid_module_net_connect_pb_graph_pin(module_manager, grid_module,
                                               child_module, child_instance,
                                               grid_type_descriptor,
                                               &(top_pb_graph_node->input_pins[iport][ipin]),
                                               border_side,
                                               INPUT2INPUT_INTERC);

    }
  }

  for (int iport = 0; iport < top_pb_graph_node->num_output_ports; ++iport) {
    for (int ipin = 0; ipin < top_pb_graph_node->num_output_pins[iport]; ++ipin) {
      add_grid_module_net_connect_pb_graph_pin(module_manager, grid_module,
                                               child_module, child_instance,
                                               grid_type_descriptor,
                                               &(top_pb_graph_node->output_pins[iport][ipin]),
                                               border_side,
                                               OUTPUT2OUTPUT_INTERC);
    }
  }

  for (int iport = 0; iport < top_pb_graph_node->num_clock_ports; ++iport) {
    for (int ipin = 0; ipin < top_pb_graph_node->num_clock_pins[iport]; ++ipin) {
      add_grid_module_net_connect_pb_graph_pin(module_manager, grid_module,
                                               child_module, child_instance,
                                               grid_type_descriptor,
                                               &(top_pb_graph_node->clock_pins[iport][ipin]),
                                               border_side,
                                               INPUT2INPUT_INTERC);
    } 
  }
}

/********************************************************************
 * Print Verilog modules of a primitive node in the pb_graph_node graph
 * This generic function can support all the different types of primitive nodes
 * i.e., Look-Up Tables (LUTs), Flip-flops (FFs) and hard logic blocks such as adders.
 *
 * The Verilog module will consist of two parts:
 * 1. Logic module of the primitive node
 *    This module performs the logic function of the block
 * 2. Memory module of the primitive node
 *    This module stores the configuration bits for the logic module
 *    if the logic module is a programmable resource, such as LUT
 *
 * Verilog module structure:
 *
 *       Primitive block
 *     +---------------------------------------+
 *     |                                       | 
 *     |      +---------+    +---------+       |
 *  in |----->|         |--->|         |<------|configuration lines
 *     |      |  Logic  |... |  Memory |       |
 *  out|<-----|         |--->|         |       |
 *     |      +---------+    +---------+       |
 *     |                                       | 
 *     +---------------------------------------+
 *
 *******************************************************************/
static 
void print_verilog_primitive_block(std::fstream& fp,
                                   ModuleManager& module_manager,
                                   const CircuitLibrary& circuit_lib,
                                   t_sram_orgz_info* cur_sram_orgz_info,
                                   t_pb_graph_node* primitive_pb_graph_node,
                                   const e_side& io_side,
                                   const bool& use_explicit_mapping) {
  /* Ensure a valid file handler */ 
  check_file_handler(fp);

  /* Ensure a valid pb_graph_node */ 
  if (NULL == primitive_pb_graph_node) {
    vpr_printf(TIO_MESSAGE_ERROR,
               "(File:%s,[LINE%d]) Invalid primitive_pb_graph_node!\n",
               __FILE__, __LINE__);
    exit(1);
  }

  /* Find the circuit model id linked to the pb_graph_node */
  CircuitModelId& primitive_model = primitive_pb_graph_node->pb_type->circuit_model;

  /* Generate the module name for this primitive pb_graph_node*/
  std::string primitive_module_name_prefix(grid_verilog_file_name_prefix);
  /* Add side string to the name if it is valid, this is mainly for I/O block */
  if (NUM_SIDES != io_side) {
    Side side_manager(io_side);
    primitive_module_name_prefix += std::string(side_manager.to_string());
    primitive_module_name_prefix += std::string("_");
  }
  std::string primitive_module_name = generate_physical_block_module_name(primitive_module_name_prefix, primitive_pb_graph_node->pb_type);

  /* Create a module of the primitive LUT and register it to module manager */
  ModuleId primitive_module = module_manager.add_module(primitive_module_name);
  /* Ensure that the module has been created and thus unique! */
  VTR_ASSERT(ModuleId::INVALID() != primitive_module);

  /* Find the global ports required by the primitive node, and add them to the module */
  std::vector<CircuitPortId> primitive_model_global_ports = circuit_lib.model_global_ports(primitive_model, true);
  for (auto port : primitive_model_global_ports) {
    /* The global I/O of the FPGA has a special name */
    BasicPort module_port(circuit_lib.port_lib_name(port), circuit_lib.port_size(port));
    module_manager.add_port(primitive_module, module_port, ModuleManager::MODULE_GLOBAL_PORT);
  }

  /* Find the inout ports required by the primitive node, and add them to the module
   * This is mainly due to the I/O blocks, which have inout ports for the top-level fabric
   */
  if (SPICE_MODEL_IOPAD == circuit_lib.model_type(primitive_model)) {
    std::vector<CircuitPortId> primitive_model_inout_ports = circuit_lib.model_ports_by_type(primitive_model, SPICE_MODEL_PORT_INOUT);
    for (auto port : primitive_model_inout_ports) {
      BasicPort module_port(generate_fpga_global_io_port_name(std::string(gio_inout_prefix), circuit_lib, primitive_model), circuit_lib.port_size(port));
      module_manager.add_port(primitive_module, module_port, ModuleManager::MODULE_GPIO_PORT);
    }
  }
  /* Note: to cooperate with the pb_type hierarchy and connections, we add the port of primitive pb_type here.
   * Since we have linked pb_type ports to circuit models when setting up FPGA-X2P,
   * no ports of the circuit model will be missing here  
   */
  add_primitive_pb_type_ports_to_module_manager(module_manager, primitive_module, primitive_pb_graph_node->pb_type); 

  /* Add configuration ports */
  /* Shared SRAM ports*/
  size_t num_shared_config_bits = find_circuit_num_shared_config_bits(circuit_lib, primitive_model, cur_sram_orgz_info->type);
  if (0 < num_shared_config_bits) {
    /* Check: this SRAM organization type must be memory-bank ! */
    VTR_ASSERT( SPICE_SRAM_MEMORY_BANK == cur_sram_orgz_info->type );
    /* Generate a list of ports */
    add_reserved_sram_ports_to_module_manager(module_manager, primitive_module, 
                                              num_shared_config_bits); 
  }

  /* TODO: this should be added to the cur_sram_orgz_info !!! */
  t_spice_model* mem_model = NULL;
  get_sram_orgz_info_mem_model(cur_sram_orgz_info, & mem_model);
  CircuitModelId sram_model = circuit_lib.model(mem_model->name);  
  VTR_ASSERT(CircuitModelId::INVALID() != sram_model);

  /* Regular (independent) SRAM ports */
  size_t num_config_bits = find_circuit_num_config_bits(circuit_lib, primitive_model);
  if (0 < num_config_bits) {
    add_sram_ports_to_module_manager(module_manager, primitive_module,
                                     circuit_lib, sram_model, cur_sram_orgz_info->type,
                                     num_config_bits);
  }

  /* Find the module id in the module manager */
  ModuleId logic_module = module_manager.find_module(circuit_lib.model_name(primitive_model));
  VTR_ASSERT(ModuleId::INVALID() != logic_module);
  size_t logic_instance_id = module_manager.num_instance(primitive_module, logic_module); 
  /* Add the logic module as a child of primitive module */
  module_manager.add_child_module(primitive_module, logic_module);

  /* Add nets to connect the logic model ports to pb_type ports */
  add_primitive_pb_type_module_nets(module_manager, primitive_module, logic_module, logic_instance_id, circuit_lib, primitive_pb_graph_node->pb_type);

  /* Add the associated memory module as a child of primitive module */
  std::string memory_module_name = generate_memory_module_name(circuit_lib, primitive_model, sram_model, std::string(verilog_mem_posfix));
  ModuleId memory_module = module_manager.find_module(memory_module_name);

  /* Vectors to record all the memory modules have been added
   * They are used to add module nets of configuration bus
   */
  std::vector<ModuleId> memory_modules;
  std::vector<size_t> memory_instances;

  /* If there is no memory module required, we can skip the assocated net addition */
  if (ModuleId::INVALID() != memory_module) {
    size_t memory_instance_id = module_manager.num_instance(primitive_module, memory_module); 
    /* Add the memory module as a child of primitive module */
    module_manager.add_child_module(primitive_module, memory_module);
  
    /* Add nets to connect regular and mode-select SRAM ports to the SRAM port of memory module */
    add_module_nets_between_logic_and_memory_sram_bus(module_manager, primitive_module, 
                                                      logic_module, logic_instance_id,
                                                      memory_module, memory_instance_id,
                                                      circuit_lib, primitive_model);
    /* Record memory-related information */
    memory_modules.push_back(memory_module);
    memory_instances.push_back(memory_instance_id);
  }
  /* Add all the nets to connect configuration ports from memory module to primitive modules
   * This is a one-shot addition that covers all the memory modules in this primitive module!
   */
  if (false == memory_modules.empty()) {
    add_module_nets_memory_config_bus(module_manager, primitive_module, 
                                      memory_modules, memory_instances,
                                      cur_sram_orgz_info->type, circuit_lib.design_tech_type(sram_model));
  }
  
  /* Write the verilog module */
  write_verilog_module_to_file(fp, module_manager, primitive_module, use_explicit_mapping);

  /* Add an empty line as a splitter */
  fp << std::endl;
}

/********************************************************************
 * This function add a net for a pin-to-pin connection defined in pb_graph
 * It supports two cases for the pin-to-pin connection
 * 1. The net source is a pb_graph_pin while the net sink is a pin of an interconnection
 * 2. The net source is a pin of an interconnection while the net sink a pb_graph_pin
 * The type is enabled by an argument pin2pin_interc_type
 *******************************************************************/
static 
void add_module_pb_graph_pin2pin_net(ModuleManager& module_manager,
                                     const ModuleId& pb_module,
                                     const ModuleId& interc_module,
                                     const size_t& interc_instance,
                                     const std::string& interc_port_name,
                                     const size_t& interc_pin_id,
                                     const std::string& module_name_prefix,
                                     t_pb_graph_pin* pb_graph_pin,
                                     const enum e_spice_pin2pin_interc_type& pin2pin_interc_type) {

  ModuleNetId pin2pin_net = module_manager.create_module_net(pb_module);

  /* Find port and pin ids for the module, which is the parent of pb_graph_pin  */
  t_pb_type* pin_pb_type = pb_graph_pin->parent_node->pb_type;
  /* Find the module contains the source pin */
  ModuleId pin_pb_type_module = module_manager.find_module(generate_physical_block_module_name(module_name_prefix, pin_pb_type));
  VTR_ASSERT(true == module_manager.valid_module_id(pin_pb_type_module));
  size_t pin_pb_type_instance = 0; /* Deposite the instance with a zero, which is the default value is the source module is actually pb_module itself */
  if (pin_pb_type_module != pb_module) {
    pin_pb_type_instance = pb_graph_pin->parent_node->placement_index;
    /* Ensure this is an valid instance */
    VTR_ASSERT(pin_pb_type_instance < module_manager.num_instance(pb_module, pin_pb_type_module));
  }
  ModulePortId pin_module_port_id = module_manager.find_module_port(pin_pb_type_module, generate_pb_type_port_name(pb_graph_pin->port)); 
  VTR_ASSERT(true == module_manager.valid_module_port_id(pin_pb_type_module, pin_module_port_id));
  size_t pin_module_pin_id = pb_graph_pin->pin_number;
  /* Ensure this is an valid pin index */
  VTR_ASSERT(pin_module_pin_id < module_manager.module_port(pin_pb_type_module, pin_module_port_id).get_width());

  /* Find port and pin ids for the interconnection module */
  ModulePortId interc_port_id = module_manager.find_module_port(interc_module, interc_port_name); 
  VTR_ASSERT(true == module_manager.valid_module_port_id(interc_module, interc_port_id));
  /* Ensure this is an valid pin index */
  VTR_ASSERT(interc_pin_id < module_manager.module_port(interc_module, interc_port_id).get_width());
  
  /* Add net sources and sinks:
   * For input-to-input connection, net_source is pin_graph_pin, while net_sink is interc pin   
   * For output-to-output connection, net_source is interc pin, while net_sink is pin_graph pin   
   */
  switch (pin2pin_interc_type) {
  case INPUT2INPUT_INTERC:
    module_manager.add_module_net_source(pb_module, pin2pin_net, pin_pb_type_module, pin_pb_type_instance, pin_module_port_id, pin_module_pin_id);
    module_manager.add_module_net_sink(pb_module, pin2pin_net, interc_module, interc_instance, interc_port_id, interc_pin_id);
    break;
  case OUTPUT2OUTPUT_INTERC:
    module_manager.add_module_net_source(pb_module, pin2pin_net, interc_module, interc_instance, interc_port_id, interc_pin_id);
    module_manager.add_module_net_sink(pb_module, pin2pin_net, pin_pb_type_module, pin_pb_type_instance, pin_module_port_id, pin_module_pin_id);
    break;
  default:
    vpr_printf(TIO_MESSAGE_ERROR,
               "(File:%s, [LINE%d]) Invalid pin-to-pin interconnection type!\n",
               __FILE__, __LINE__);
    exit(1);
  }
}

/********************************************************************
 * We check output_pins of cur_pb_graph_node and its the input_edges
 * Built the interconnections between outputs of cur_pb_graph_node and outputs of child_pb_graph_node
 *   src_pb_graph_node.[in|out]_pins -----------------> des_pb_graph_node.[in|out]pins
 *                                        /|\
 *                                         |
 *                         input_pins,   edges,       output_pins
 *
 * This function does the following task:
 * 1. identify pin interconnection type, 
 * 2. Identify the number of fan-in (Consider interconnection edges of only selected mode)
 * 3. Add mux/direct connection as a child module to pb_module
 * 4. Add nets related to the mux/direction 
 *******************************************************************/
static 
void add_module_pb_graph_pin_interc(ModuleManager& module_manager,
                                    const ModuleId& pb_module,
                                    std::vector<ModuleId>& memory_modules,
                                    std::vector<size_t>& memory_instances,
                                    const CircuitLibrary& circuit_lib,
                                    const std::string& module_name_prefix,
                                    t_pb_graph_pin* des_pb_graph_pin,
                                    t_mode* physical_mode) {
  /* Find the number of fan-in and detailed interconnection information 
   * related to the destination pb_graph_pin 
   */
  int fan_in = 0;
  t_interconnect* cur_interc = NULL;
  find_interc_fan_in_des_pb_graph_pin(des_pb_graph_pin, physical_mode, &cur_interc, &fan_in);

  /* If no interconnection is needed, we can return early */
  if ((NULL == cur_interc) || (0 == fan_in)) { 
    return;
  }

  /* Initialize the interconnection type that will be physically implemented in module */
  enum e_interconnect verilog_interc_type = determine_actual_pb_interc_type(cur_interc, fan_in);

  /* Find input ports of the wire module */
  std::vector<CircuitPortId> interc_model_inputs = circuit_lib.model_ports_by_type(cur_interc->circuit_model, SPICE_MODEL_PORT_INPUT, true); /* the last argument to guarantee that we ignore any global inputs */
  /* Find output ports of the wire module */
  std::vector<CircuitPortId> interc_model_outputs = circuit_lib.model_ports_by_type(cur_interc->circuit_model, SPICE_MODEL_PORT_OUTPUT, true); /* the last argument to guarantee that we ignore any global ports */

  /* Ensure that we have only 1 input port and 1 output port, this is valid for both wire and MUX */
  VTR_ASSERT(1 == interc_model_inputs.size());
  VTR_ASSERT(1 == interc_model_outputs.size());

  /* Branch on the type of physical implementation,
   * We add instances of programmable interconnection 
   */ 
  switch (verilog_interc_type) {
  case DIRECT_INTERC: {
    /* Ensure direct interc has only one fan-in */
    VTR_ASSERT(1 == fan_in);

    /* For more than one mode defined, the direct interc has more than one input_edge ,
     * We need to find which edge is connected the pin we want
     */
    int iedge = 0;
    for (iedge = 0; iedge < des_pb_graph_pin->num_input_edges; iedge++) {
      if (cur_interc == des_pb_graph_pin->input_edges[iedge]->interconnect) {
        break;
      }
    }
    t_pb_graph_pin* src_pb_graph_pin = des_pb_graph_pin->input_edges[iedge]->input_pins[0];

    /* Ensure that circuit model is a wire */ 
    VTR_ASSERT(SPICE_MODEL_WIRE == circuit_lib.model_type(cur_interc->circuit_model));
    /* Find the wire module in the module manager */
    ModuleId wire_module = module_manager.find_module(circuit_lib.model_name(cur_interc->circuit_model));
    VTR_ASSERT(true == module_manager.valid_module_id(wire_module));
    /* Get the instance id and add an instance of wire */
    size_t wire_instance = module_manager.num_instance(pb_module, wire_module);
    module_manager.add_child_module(pb_module, wire_module);
   
    /* Ensure input and output ports of the wire model has only 1 pin respectively */
    VTR_ASSERT(1 == circuit_lib.port_size(interc_model_inputs[0]));
    VTR_ASSERT(1 == circuit_lib.port_size(interc_model_outputs[0]));

    /* Add nets to connect the wires to ports of pb_module */
    /* First net is to connect input of src_pb_graph_node to input of the wire module */ 
    add_module_pb_graph_pin2pin_net(module_manager, pb_module, 
                                    wire_module, wire_instance, 
                                    circuit_lib.port_lib_name(interc_model_inputs[0]),
                                    0, /* wire input port has only 1 pin */
                                    module_name_prefix,
                                    src_pb_graph_pin, 
                                    INPUT2INPUT_INTERC);

    /* Second net is to connect output of the wire module to output of des_pb_graph_pin */ 
    add_module_pb_graph_pin2pin_net(module_manager, pb_module, 
                                    wire_module, wire_instance, 
                                    circuit_lib.port_lib_name(interc_model_outputs[0]),
                                    0, /* wire output port has only 1 pin */
                                    module_name_prefix,
                                    des_pb_graph_pin, 
                                    OUTPUT2OUTPUT_INTERC);
    break;
  }
  case COMPLETE_INTERC:
  case MUX_INTERC: {
    /* Check: MUX should have at least 2 fan_in */
    VTR_ASSERT((2 == fan_in)||(2 < fan_in));
    /* Ensure that circuit model is a MUX */ 
    VTR_ASSERT(SPICE_MODEL_MUX == circuit_lib.model_type(cur_interc->circuit_model));
    /* Find the wire module in the module manager */
    ModuleId mux_module = module_manager.find_module(generate_mux_subckt_name(circuit_lib, cur_interc->circuit_model, fan_in, std::string()));
    VTR_ASSERT(true == module_manager.valid_module_id(mux_module));

    /* Instanciate the MUX */
    size_t mux_instance = module_manager.num_instance(pb_module, mux_module);
    module_manager.add_child_module(pb_module, mux_module);

    /* Instanciate a memory module for the MUX */
    std::string mux_mem_module_name = generate_mux_subckt_name(circuit_lib, 
                                                               cur_interc->circuit_model, 
                                                               fan_in, 
                                                               std::string(verilog_mem_posfix));
    ModuleId mux_mem_module = module_manager.find_module(mux_mem_module_name);
    VTR_ASSERT(true == module_manager.valid_module_id(mux_mem_module));
    size_t mux_mem_instance = module_manager.num_instance(pb_module, mux_mem_module);
    module_manager.add_child_module(pb_module, mux_mem_module);

    /* Add nets to connect SRAM ports of the MUX to the SRAM port of memory module */
    add_module_nets_between_logic_and_memory_sram_bus(module_manager, pb_module, 
                                                      mux_module, mux_instance,
                                                      mux_mem_module, mux_mem_instance,
                                                      circuit_lib, cur_interc->circuit_model);

    /* Update memory modules and memory instance list */
    memory_modules.push_back(mux_mem_module);
    memory_instances.push_back(mux_mem_instance);

    /* Ensure output port of the MUX model has only 1 pin, 
     * while the input port size is dependent on the architecture conext, 
     * no constaints on the circuit model definition 
     */
    VTR_ASSERT(1 == circuit_lib.port_size(interc_model_outputs[0]));

    /* Create nets to wire between the MUX and PB module */
    /* Add a net to wire the inputs of the multiplexer to its source pb_graph_pin inside pb_module 
     * Here is a tricky part. 
     * Not every input edges from the destination pb_graph_pin is used in the physical_model of pb_type
     * So, we will skip these input edges when building nets 
     */
    int mux_input_pin_id = 0;
    for (int iedge = 0; iedge < des_pb_graph_pin->num_input_edges; iedge++) {
      if (physical_mode != des_pb_graph_pin->input_edges[iedge]->interconnect->parent_mode) {
        continue;
      }
      /* Ensure that the input edge has only 1 input pin! */
      check_pb_graph_edge(*(des_pb_graph_pin->input_edges[iedge]));
      t_pb_graph_pin* src_pb_graph_pin = des_pb_graph_pin->input_edges[iedge]->input_pins[0];
      /* Add a net, set its source and sink */
      add_module_pb_graph_pin2pin_net(module_manager, pb_module, 
                                      mux_module, mux_instance, 
                                      circuit_lib.port_lib_name(interc_model_inputs[0]),
                                      mux_input_pin_id,
                                      module_name_prefix,
                                      src_pb_graph_pin, 
                                      INPUT2INPUT_INTERC);
      mux_input_pin_id++;
    }
    /* Ensure all the fan_in has been covered */
    VTR_ASSERT(mux_input_pin_id == fan_in);

    /* Add a net to wire the output of the multiplexer to des_pb_graph_pin */
    add_module_pb_graph_pin2pin_net(module_manager, pb_module, 
                                    mux_module, mux_instance, 
                                    circuit_lib.port_lib_name(interc_model_outputs[0]),
                                    0, /* MUX should have only 1 pin in its output port */
                                    module_name_prefix,
                                    des_pb_graph_pin, 
                                    OUTPUT2OUTPUT_INTERC);
    break;
  }
  default:
    vpr_printf(TIO_MESSAGE_ERROR,
               "(File:%s,[LINE%d])Invalid interconnection type for %s [at Architecture XML LINE%d]!\n",
               __FILE__, __LINE__, cur_interc->name, cur_interc->line_num);
    exit(1);
  }
}

/********************************************************************
 * Add modules and nets for programmable/non-programmable interconnections 
 * which end to a port of pb_module
 * This function will add the following elements to a module
 * 1. Instances of direct connections
 * 2. Instances of programmable routing multiplexers
 * 3. nets to connect direct connections/multiplexer 
 *
 *  +-----------------------------------------+
 *  |                                        
 *  |    +--------------+    +------------+
 *  |--->|              |--->|            |
 *  |... | Multiplexers |... |            |
 *  |--->|              |--->|            |
 *  |    +--------------+    |   des_pb_  | 
 *  |                        | graph_node |                      
 *  |    +--------------+    |            |
 *  |--->|              |--->|            |
 *  | ...|    Direct    |... |            |
 *  |--->|  Connections |--->|            |
 *  |    +--------------+    +------------+
 *  |                                        
 *  +----------------------------------------+

 *
 *  Note: this function should be run after ALL the child pb_modules
 *  have been added to the pb_module and ALL the ports defined 
 *  in pb_type have been added to the pb_module!!!
 *
 ********************************************************************/
static 
void add_module_pb_graph_port_interc(ModuleManager& module_manager,
                                     const ModuleId& pb_module,
                                     std::vector<ModuleId>& memory_modules,
                                     std::vector<size_t>& memory_instances,
                                     const CircuitLibrary& circuit_lib,
                                     t_pb_graph_node* des_pb_graph_node,
                                     const std::string& module_name_prefix,
                                     const e_spice_pb_port_type& pb_port_type,
                                     t_mode* physical_mode) {
  switch (pb_port_type) {
  case SPICE_PB_PORT_INPUT: {
    for (int iport = 0; iport < des_pb_graph_node->num_input_ports; ++iport) {
      for (int ipin = 0; ipin < des_pb_graph_node->num_input_pins[iport]; ++ipin) {
        /* Get the selected edge of current pin*/
        add_module_pb_graph_pin_interc(module_manager, pb_module,
                                       memory_modules, memory_instances,
                                       circuit_lib,
                                       module_name_prefix,
                                       &(des_pb_graph_node->input_pins[iport][ipin]),
                                       physical_mode);
      }
    }
    break;
  }
  case SPICE_PB_PORT_OUTPUT: {
    for (int iport = 0; iport < des_pb_graph_node->num_output_ports; ++iport) {
      for (int ipin = 0; ipin < des_pb_graph_node->num_output_pins[iport]; ++ipin) {
        add_module_pb_graph_pin_interc(module_manager, pb_module,
                                       memory_modules, memory_instances,
                                       circuit_lib,
                                       module_name_prefix,
                                       &(des_pb_graph_node->output_pins[iport][ipin]),
                                       physical_mode);
      }
    }
    break;
  }
  case SPICE_PB_PORT_CLOCK: {
    for (int iport = 0; iport < des_pb_graph_node->num_clock_ports; ++iport) {
      for (int ipin = 0; ipin < des_pb_graph_node->num_clock_pins[iport]; ++ipin) {
        add_module_pb_graph_pin_interc(module_manager, pb_module,
                                       memory_modules, memory_instances,
                                       circuit_lib,
                                       module_name_prefix,
                                       &(des_pb_graph_node->clock_pins[iport][ipin]),
                                       physical_mode);
      }
    }
    break;
  }
  default:
   vpr_printf(TIO_MESSAGE_ERROR,
              "(File:%s,[LINE%d]) Invalid pb port type!\n",
               __FILE__, __LINE__);
    exit(1);
  }
}

/********************************************************************
 * TODO: 
 * Add modules and nets for programmable/non-programmable interconnections 
 * inside a module of pb_type
 * This function will add the following elements to a module
 * 1. Instances of direct connections
 * 2. Instances of programmable routing multiplexers
 * 3. nets to connect direct connections/multiplexer 
 *
 *   Pb_module
 *  +--------------------------------------------------------------+
 *  |                                                              |
 *  |    +--------------+    +------------+    +--------------+    |
 *  |--->|              |--->|            |--->|              |--->|
 *  |... | Multiplexers |... |            |... | Multiplexers |... |
 *  |--->|              |--->|            |--->|              |--->|
 *  |    +--------------+    |   Child    |    +--------------+    |
 *  |                        | Pb_modules |                        |
 *  |    +--------------+    |            |    +--------------+    |
 *  |--->|              |--->|            |--->|              |--->|
 *  | ...|    Direct    |... |            |... |    Direct    |... |
 *  |--->|  Connections |--->|            |--->|  Connections |--->|
 *  |    +--------------+    +------------+    +--------------+    |
 *  |                                                              |
 *  +--------------------------------------------------------------+
 *
 *  Note: this function should be run after ALL the child pb_modules
 *  have been added to the pb_module and ALL the ports defined 
 *  in pb_type have been added to the pb_module!!!
 *
 ********************************************************************/
static 
void add_module_pb_graph_interc(ModuleManager& module_manager,
                                const ModuleId& pb_module,
                                std::vector<ModuleId>& memory_modules,
                                std::vector<size_t>& memory_instances,
                                const CircuitLibrary& circuit_lib,
                                t_pb_graph_node* physical_pb_graph_node,
                                const std::string& module_name_prefix,
                                const int& physical_mode_index) {
  /* Check cur_pb_graph_node*/
  if (NULL == physical_pb_graph_node) {
    vpr_printf(TIO_MESSAGE_ERROR,
               "(File:%s,[LINE%d]) Invalid cur_pb_graph_node.\n", 
               __FILE__, __LINE__); 
    exit(1);
  }
  
  /* Assign physical mode */
  t_mode* physical_mode = &(physical_pb_graph_node->pb_type->modes[physical_mode_index]);

  /* We check output_pins of cur_pb_graph_node and its the input_edges
   * Built the interconnections between outputs of cur_pb_graph_node and outputs of child_pb_graph_node
   *   child_pb_graph_node.output_pins -----------------> cur_pb_graph_node.outpins
   *                                        /|\
   *                                         |
   *                         input_pins,   edges,       output_pins
   */ 
  add_module_pb_graph_port_interc(module_manager, pb_module,
                                  memory_modules, memory_instances,
                                  circuit_lib, 
                                  physical_pb_graph_node, 
                                  module_name_prefix, 
                                  SPICE_PB_PORT_OUTPUT,
                                  physical_mode);
  
  /* We check input_pins of child_pb_graph_node and its the input_edges
   * Built the interconnections between inputs of cur_pb_graph_node and inputs of child_pb_graph_node
   *   cur_pb_graph_node.input_pins -----------------> child_pb_graph_node.input_pins
   *                                        /|\
   *                                         |
   *                         input_pins,   edges,       output_pins
   */ 
  for (int child = 0; child < physical_pb_graph_node->pb_type->modes[physical_mode_index].num_pb_type_children; ++child) {
    for (int inst = 0; inst < physical_pb_graph_node->pb_type->modes[physical_mode_index].pb_type_children[child].num_pb; ++inst) {
      t_pb_graph_node* child_pb_graph_node = &(physical_pb_graph_node->child_pb_graph_nodes[physical_mode_index][child][inst]);
      /* For each child_pb_graph_node input pins*/
      add_module_pb_graph_port_interc(module_manager, pb_module,
                                      memory_modules, memory_instances,
                                      circuit_lib, 
                                      child_pb_graph_node, 
                                      module_name_prefix, 
                                      SPICE_PB_PORT_INPUT,
                                      physical_mode);

      /* For each child_pb_graph_node clock pins*/
      add_module_pb_graph_port_interc(module_manager, pb_module,
                                      memory_modules, memory_instances,
                                      circuit_lib, 
                                      child_pb_graph_node, 
                                      module_name_prefix, 
                                      SPICE_PB_PORT_CLOCK,
                                      physical_mode);
    }
  }
}

/********************************************************************
 * Print Verilog modules of physical blocks inside a grid (CLB, I/O. etc.)
 * This function will traverse the graph of complex logic block (t_pb_graph_node)
 * in a recursive way, using a Depth First Search (DFS) algorithm.
 * As such, primitive physical blocks (LUTs, FFs, etc.), leaf node of the pb_graph
 * will be printed out first, while the top-level will be printed out in the last
 *
 * Note: this function will print a unique Verilog module for each type of 
 * t_pb_graph_node, i.e., t_pb_type, in the graph, in order to enable highly 
 * hierarchical Verilog organization as well as simplify the Verilog file sizes.
 *
 * Note: DFS is the right way. Do NOT use BFS.
 * DFS can guarantee that all the sub-modules can be registered properly
 * to its parent in module manager  
 *******************************************************************/
static 
void print_verilog_physical_blocks_rec(std::fstream& fp,
                                       ModuleManager& module_manager,
                                       const CircuitLibrary& circuit_lib,
                                       const MuxLibrary& mux_lib,
                                       t_sram_orgz_info* cur_sram_orgz_info,
                                       t_pb_graph_node* physical_pb_graph_node,
                                       const e_side& io_side,
                                       const bool& use_explicit_mapping) {
  /* Check the file handler*/ 
  check_file_handler(fp);

  /* Check cur_pb_graph_node*/
  if (NULL == physical_pb_graph_node) {
    vpr_printf(TIO_MESSAGE_ERROR,
               "(File:%s,[LINE%d]) Invalid cur_pb_graph_node.\n", 
               __FILE__, __LINE__); 
    exit(1);
  }

  /* Get the pb_type definition related to the node */
  t_pb_type* physical_pb_type = physical_pb_graph_node->pb_type; 

  /* Find the mode that physical implementation of a pb_type */
  int physical_mode_index = find_pb_type_physical_mode_index((*physical_pb_type));

  /* For non-leaf node in the pb_type graph: 
   * Recursively Depth-First Generate all the child pb_type at the level 
   */
  if (FALSE == is_primitive_pb_type(physical_pb_type)) { 
    for (int ipb = 0; ipb < physical_pb_type->modes[physical_mode_index].num_pb_type_children; ++ipb) {
      /* Go recursive to visit the children */
      print_verilog_physical_blocks_rec(fp, module_manager, circuit_lib, mux_lib, 
                                        cur_sram_orgz_info, 
                                        &(physical_pb_graph_node->child_pb_graph_nodes[physical_mode_index][ipb][0]),
                                        io_side,
                                        use_explicit_mapping);
    }
  }

  /* For leaf node, a primitive Verilog module will be generated */
  if (TRUE == is_primitive_pb_type(physical_pb_type)) { 
    print_verilog_primitive_block(fp, module_manager, circuit_lib,
                                  cur_sram_orgz_info, 
                                  physical_pb_graph_node, 
                                  io_side, 
                                  use_explicit_mapping); 
    /* Finish for primitive node, return */
    return;
  }

  /* Generate the name of the Verilog module for this pb_type */
  std::string pb_module_name_prefix(grid_verilog_file_name_prefix);
  /* Add side string to the name if it is valid */
  if (NUM_SIDES != io_side) {
    Side side_manager(io_side);
    pb_module_name_prefix += std::string(side_manager.to_string());
    pb_module_name_prefix += std::string("_");
  }
  std::string pb_module_name = generate_physical_block_module_name(pb_module_name_prefix, physical_pb_type);

  /* Register the Verilog module in module manager */
  ModuleId pb_module = module_manager.add_module(pb_module_name);
  VTR_ASSERT(ModuleId::INVALID() != pb_module);

  /* Add ports to the Verilog module */
  add_pb_type_ports_to_module_manager(module_manager, pb_module, physical_pb_type); 

  /* Vectors to record all the memory modules have been added
   * They are used to add module nets of configuration bus
   */
  std::vector<ModuleId> memory_modules;
  std::vector<size_t> memory_instances;

  /* TODO: this should be added to the cur_sram_orgz_info !!! */
  t_spice_model* mem_model = NULL;
  get_sram_orgz_info_mem_model(cur_sram_orgz_info, & mem_model);
  CircuitModelId sram_model = circuit_lib.model(mem_model->name);  
  VTR_ASSERT(CircuitModelId::INVALID() != sram_model);

  /* Add all the child Verilog modules as instances */
  for (int ichild = 0; ichild < physical_pb_type->modes[physical_mode_index].num_pb_type_children; ++ichild) {
    /* Get the name and module id for this child pb_type */
    std::string child_pb_module_name = generate_physical_block_module_name(pb_module_name_prefix, &(physical_pb_type->modes[physical_mode_index].pb_type_children[ichild]));
    ModuleId child_pb_module = module_manager.find_module(child_pb_module_name);
    /* We must have one valid id! */
    VTR_ASSERT(true == module_manager.valid_module_id(child_pb_module));

    /* Each child may exist multiple times in the hierarchy*/
    for (int inst = 0; inst < physical_pb_type->modes[physical_mode_index].pb_type_children[ichild].num_pb; ++inst) {
      size_t child_instance_id = module_manager.num_instance(pb_module, child_pb_module); 
      /* Ensure the instance of this child module is the same as placement index,
       * This check is necessary because placement_index is used to identify instance id for children 
       * when adding local interconnection for this pb_type 
       */
      VTR_ASSERT(child_instance_id == (size_t)physical_pb_graph_node->child_pb_graph_nodes[physical_mode_index][ichild][inst].placement_index);

      /* Add the memory module as a child of primitive module */
      module_manager.add_child_module(pb_module, child_pb_module); 
      /* Identify if this sub module includes configuration bits, 
       * we will update the memory module and instance list
       */
      if (0 < find_module_num_config_bits(module_manager, child_pb_module,
                                          circuit_lib, sram_model, 
                                          cur_sram_orgz_info->type)) {
        memory_modules.push_back(child_pb_module);
        memory_instances.push_back(child_instance_id);
      }
    }
  }

  /* Add modules and nets for programmable/non-programmable interconnections 
   * inside the Verilog module 
   */
  add_module_pb_graph_interc(module_manager, pb_module,
                             memory_modules, memory_instances,
                             circuit_lib, physical_pb_graph_node,
                             pb_module_name_prefix,
                             physical_mode_index);

  /* Add global ports to the pb_module:
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the global ports from the child modules and build a list of it
   */
  add_module_global_ports_from_child_modules(module_manager, pb_module);

  /* Count GPIO ports from the sub-modules under this Verilog module 
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  add_module_gpio_ports_from_child_modules(module_manager, pb_module);

  /* Count shared SRAM ports from the sub-modules under this Verilog module
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  size_t module_num_shared_config_bits = find_module_num_shared_config_bits_from_child_modules(module_manager, pb_module); 
  if (0 < module_num_shared_config_bits) {
    add_reserved_sram_ports_to_module_manager(module_manager, pb_module, module_num_shared_config_bits);
  }

  /* Count SRAM ports from the sub-modules under this Verilog module
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  size_t module_num_config_bits = find_module_num_config_bits_from_child_modules(module_manager, pb_module, circuit_lib, sram_model, cur_sram_orgz_info->type); 
  if (0 < module_num_config_bits) {
    add_sram_ports_to_module_manager(module_manager, pb_module, circuit_lib, sram_model, cur_sram_orgz_info->type, module_num_config_bits);
  }

  /* Add module nets to connect memory cells inside
   * This is a one-shot addition that covers all the memory modules in this pb module!
   */
  if (false == memory_modules.empty()) {
    add_module_nets_memory_config_bus(module_manager, pb_module, 
                                      memory_modules, memory_instances,
                                      cur_sram_orgz_info->type, circuit_lib.design_tech_type(sram_model));
  }

  /* Comment lines */
  print_verilog_comment(fp, std::string("----- BEGIN Physical programmable logic block Verilog module: " + std::string(physical_pb_type->name) + " -----"));

  /* Write the verilog module */
  write_verilog_module_to_file(fp, module_manager, pb_module, use_explicit_mapping);

  print_verilog_comment(fp, std::string("----- END Physical programmable logic block Verilog module: " + std::string(physical_pb_type->name) + " -----"));

  /* Add an empty line as a splitter */
  fp << std::endl;
}

/*****************************************************************************
 * This function will create a Verilog file and print out a Verilog netlist 
 * for a type of physical block 
 *
 * For IO blocks: 
 * The param 'border_side' is required, which is specify which side of fabric
 * the I/O block locates at.
 *****************************************************************************/
static 
void print_verilog_grid(ModuleManager& module_manager,
                        const MuxLibrary& mux_lib,
                        const CircuitLibrary& circuit_lib,
                        t_sram_orgz_info* cur_sram_orgz_info, 
                        const std::string& verilog_dir,
                        const std::string& subckt_dir,
                        t_type_ptr phy_block_type,
                        const e_side& border_side,
                        const bool& use_explicit_mapping) {
  /* Check code: if this is an IO block, the border side MUST be valid */
  if (IO_TYPE == phy_block_type) {
    VTR_ASSERT(NUM_SIDES != border_side);
  }
  
  /* Give a name to the Verilog netlist */
  /* Create the file name for Verilog */
  std::string verilog_fname(subckt_dir 
                          + generate_grid_block_netlist_name(std::string(phy_block_type->name), 
                                                             IO_TYPE == phy_block_type, 
                                                             border_side, 
                                                             std::string(verilog_netlist_file_postfix))
                           );
  /* TODO: remove the bak file when the file is ready */
  verilog_fname += ".bak";

  /* Echo status */
  if (IO_TYPE == phy_block_type) {
    Side side_manager(border_side);
    vpr_printf(TIO_MESSAGE_INFO, 
               "Writing FPGA Verilog Netlist (%s) for logic block %s at %s side ...\n",
               verilog_fname.c_str(), phy_block_type->name, 
               side_manager.c_str());
  } else { 
    vpr_printf(TIO_MESSAGE_INFO, 
               "Writing FPGA Verilog Netlist (%s) for logic block %s...\n",
               verilog_fname.c_str(), phy_block_type->name);
  }

  /* Create the file stream */
  std::fstream fp;
  fp.open(verilog_fname, std::fstream::out | std::fstream::trunc);

  check_file_handler(fp);

  print_verilog_file_header(fp, std::string("Verilog modules for physical block: " + std::string(phy_block_type->name) + "]")); 

  /* Print preprocessing flags */
  print_verilog_include_defines_preproc_file(fp, verilog_dir);

  /* Print Verilog modules for all the pb_types/pb_graph_nodes
   * use a Depth-First Search Algorithm to print the sub-modules 
   * Note: DFS is the right way. Do NOT use BFS.
   * DFS can guarantee that all the sub-modules can be registered properly
   * to its parent in module manager  
   */
  print_verilog_comment(fp, std::string("---- BEGIN Sub-module of physical block:" + std::string(phy_block_type->name) + " ----"));

  /* Print Verilog modules starting from the top-level pb_type/pb_graph_node, and traverse the graph in a recursive way */
  print_verilog_physical_blocks_rec(fp, module_manager, circuit_lib, mux_lib, 
                                    cur_sram_orgz_info, 
                                    phy_block_type->pb_graph_head,
                                    border_side,
                                    use_explicit_mapping);

  print_verilog_comment(fp, std::string("---- END Sub-module of physical block:" + std::string(phy_block_type->name) + " ----"));

  /* Create a Verilog Module for the top-level physical block, and add to module manager */
  std::string grid_module_name = generate_grid_block_module_name(std::string(grid_verilog_file_name_prefix), phy_block_type->name, IO_TYPE == phy_block_type, border_side);
  ModuleId grid_module = module_manager.add_module(grid_module_name); 
  VTR_ASSERT(true == module_manager.valid_module_id(grid_module));

  /* Vectors to record all the memory modules have been added
   * They are used to add module nets of configuration bus
   */
  std::vector<ModuleId> memory_modules;
  std::vector<size_t> memory_instances;

  /* TODO: this should be added to the cur_sram_orgz_info !!! */
  t_spice_model* mem_model = NULL;
  get_sram_orgz_info_mem_model(cur_sram_orgz_info, & mem_model);
  CircuitModelId sram_model = circuit_lib.model(mem_model->name);  
  VTR_ASSERT(CircuitModelId::INVALID() != sram_model);

  /* Generate the name of the Verilog module for this pb_type */
  std::string pb_module_name_prefix(grid_verilog_file_name_prefix);
  /* Add side string to the name if it is valid */
  if (NUM_SIDES != border_side) {
    Side side_manager(border_side);
    pb_module_name_prefix += std::string(side_manager.to_string());
    pb_module_name_prefix += std::string("_");
  }
  std::string pb_module_name = generate_physical_block_module_name(pb_module_name_prefix, phy_block_type->pb_graph_head->pb_type);
  ModuleId pb_module = module_manager.find_module(pb_module_name);
  VTR_ASSERT(true == module_manager.valid_module_id(pb_module));

  /* Add all the sub modules */
  for (int iz = 0; iz < phy_block_type->capacity; ++iz) {
    size_t pb_instance_id = module_manager.num_instance(grid_module, pb_module);
    module_manager.add_child_module(grid_module, pb_module);
    /* Identify if this sub module includes configuration bits, 
     * we will update the memory module and instance list
     */
    if (0 < find_module_num_config_bits(module_manager, pb_module,
                                        circuit_lib, sram_model, 
                                        cur_sram_orgz_info->type)) {
      memory_modules.push_back(pb_module);
      memory_instances.push_back(pb_instance_id);
    }
  }

  /* Add grid ports(pins) to the module */
  add_grid_module_pb_type_ports(module_manager, grid_module,
                                phy_block_type, border_side);

  /* Add module nets to connect the pb_type ports to sub modules */
  for (const size_t& child_instance : module_manager.child_module_instances(grid_module, pb_module)) {
    add_grid_module_nets_connect_pb_type_ports(module_manager, grid_module,
                                               pb_module, child_instance,
                                               phy_block_type, border_side);
  }

  /* Add global ports to the pb_module:
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the global ports from the child modules and build a list of it
   */
  add_module_global_ports_from_child_modules(module_manager, grid_module);

  /* Count GPIO ports from the sub-modules under this Verilog module 
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  add_module_gpio_ports_from_child_modules(module_manager, grid_module);

  /* Count shared SRAM ports from the sub-modules under this Verilog module
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  size_t module_num_shared_config_bits = find_module_num_shared_config_bits_from_child_modules(module_manager, grid_module); 
  if (0 < module_num_shared_config_bits) {
    add_reserved_sram_ports_to_module_manager(module_manager, grid_module, module_num_shared_config_bits);
  }

  /* Count SRAM ports from the sub-modules under this Verilog module
   * This is a much easier job after adding sub modules (instances), 
   * we just need to find all the I/O ports from the child modules and build a list of it
   */
  size_t module_num_config_bits = find_module_num_config_bits_from_child_modules(module_manager, grid_module, circuit_lib, sram_model, cur_sram_orgz_info->type); 
  if (0 < module_num_config_bits) {
    add_sram_ports_to_module_manager(module_manager, grid_module, circuit_lib, sram_model, cur_sram_orgz_info->type, module_num_config_bits);
  }

  /* Add module nets to connect memory cells inside
   * This is a one-shot addition that covers all the memory modules in this pb module!
   */
  if (false == memory_modules.empty()) {
    add_module_nets_memory_config_bus(module_manager, grid_module, 
                                      memory_modules, memory_instances,
                                      cur_sram_orgz_info->type, circuit_lib.design_tech_type(sram_model));
  }

  /* Write the verilog module */
  print_verilog_comment(fp, std::string("----- BEGIN Grid Verilog module: " + module_manager.module_name(grid_module) + " -----"));
  write_verilog_module_to_file(fp, module_manager, grid_module, use_explicit_mapping);

  print_verilog_comment(fp, std::string("----- END Grid Verilog module: " + module_manager.module_name(grid_module) + " -----"));

  /* Add an empty line as a splitter */
  fp << std::endl;

  /* Close file handler */
  fp.close();

  /* Add fname to the linked list */
  /* TODO: add it when it is ready
  grid_verilog_subckt_file_path_head = add_one_subckt_file_name_to_llist(grid_verilog_subckt_file_path_head, verilog_fname.c_str());  
   */
}

/*****************************************************************************
 * Create logic block modules in a compact way:
 * 1. Only one module for each I/O on each border side (IO_TYPE)
 * 2. Only one module for each CLB (FILL_TYPE)
 * 3. Only one module for each heterogeneous block
 ****************************************************************************/
void print_verilog_grids(ModuleManager& module_manager,
                         const CircuitLibrary& circuit_lib,
                         const MuxLibrary& mux_lib,
                         t_sram_orgz_info* cur_sram_orgz_info,
                         const std::string& verilog_dir,
                         const std::string& subckt_dir,
                         const bool& is_explicit_mapping) {
  /* Enumerate the types, dump one Verilog module for each */
  for (int itype = 0; itype < num_types; itype++) {
    if (EMPTY_TYPE == &type_descriptors[itype]) {
    /* Bypass empty type or NULL */
      continue;
    } else if (IO_TYPE == &type_descriptors[itype]) {
      /* Special for I/O block, generate one module for each border side */
      for (int iside = 0; iside < NUM_SIDES; iside++) {
        Side side_manager(iside);
        print_verilog_grid(module_manager, mux_lib, circuit_lib,
                           cur_sram_orgz_info, 
                           verilog_dir, subckt_dir, 
                           &type_descriptors[itype],
                           side_manager.get_side(),
                           is_explicit_mapping);
      } 
      continue;
    } else if (FILL_TYPE == &type_descriptors[itype]) {
      /* For CLB */
      print_verilog_grid(module_manager, mux_lib, circuit_lib,
                         cur_sram_orgz_info, 
                         verilog_dir, subckt_dir, 
                         &type_descriptors[itype],
                         NUM_SIDES,
                         is_explicit_mapping);
      continue;
    } else {
      /* For heterogenenous blocks */
      print_verilog_grid(module_manager, mux_lib, circuit_lib,
                         cur_sram_orgz_info, 
                         verilog_dir, subckt_dir, 
                         &type_descriptors[itype],
                         NUM_SIDES,
                         is_explicit_mapping);
    }
  }

  /* Output a header file for all the logic blocks */
  vpr_printf(TIO_MESSAGE_INFO, "Generating header file for grid Verilog modules...\n");
  std::string grid_verilog_fname(logic_block_verilog_file_name);
  /* TODO: remove .bak when it is ready */
  grid_verilog_fname += ".bak";
  dump_verilog_subckt_header_file(grid_verilog_subckt_file_path_head,
                                  subckt_dir.c_str(),
                                  grid_verilog_fname.c_str());
}