// SPDX-License-Identifier: MIT
// Copyright (c) 2020-2025 RVX Project Contributors

module rvx_bus #(

  parameter NUM_DEVICES               = 1

  )(

  // Global signals

  input   wire                        clock                 ,
  input   wire                        reset                 ,

  // Interface with the manager device (Processor Core IP)

  input   wire  [31:0]                manager_rw_address    ,
  output  reg   [31:0]                manager_read_data     ,
  input   wire                        manager_read_request  ,
  output  reg                         manager_read_response ,
  input   wire  [31:0]                manager_write_data    ,
  input   wire  [3:0 ]                manager_write_strobe  ,
  input   wire                        manager_write_request ,
  output  reg                         manager_write_response,

  // Interface with the managed devices

  output  wire  [31:0]                device_rw_address     ,
  input   wire  [NUM_DEVICES*32-1:0]  device_read_data      ,
  output  wire  [NUM_DEVICES-1:0]     device_read_request   ,
  input   wire  [NUM_DEVICES-1:0]     device_read_response  ,
  output  wire  [31:0]                device_write_data     ,
  output  wire  [3:0 ]                device_write_strobe   ,
  output  wire  [NUM_DEVICES-1:0]     device_write_request  ,
  input   wire  [NUM_DEVICES-1:0]     device_write_response ,

  // Base addresses and masks of the managed devices

  input   wire  [NUM_DEVICES*32-1:0]  device_start_address  ,
  input   wire  [NUM_DEVICES*32-1:0]  device_region_size

  );

  integer i;

  reg [NUM_DEVICES*32-1:0]      device_mask_address;
  reg [NUM_DEVICES-1:0]         device_sel;
  reg [NUM_DEVICES-1:0]         device_sel_save;

  // Manager request

  assign device_rw_address      = manager_rw_address;
  assign device_read_request    = device_sel & {NUM_DEVICES{manager_read_request}};
  assign device_write_data      = manager_write_data;
  assign device_write_strobe    = manager_write_strobe;
  assign device_write_request   = device_sel & {NUM_DEVICES{manager_write_request}};

  // Device response selection

  always @(*) begin
    for (i = 0; i < NUM_DEVICES; i = i + 1) begin
      device_mask_address[i*32 +:32] = ~(device_region_size[i*32 +:32] - 1);
      if ((manager_rw_address & device_mask_address[i*32 +:32]) == device_start_address[i*32 +:32])
        device_sel[i] = 1'b1;
      else
        device_sel[i] = 1'b0;
    end
  end

  always @(posedge clock) begin
    if (reset)
      device_sel_save <= {NUM_DEVICES{1'b0}};
    else if ((manager_read_request || manager_write_request) && (|device_sel))
      device_sel_save <= device_sel;
    else
      device_sel_save <= {NUM_DEVICES{1'b0}};
  end

  always @(*) begin
    manager_read_data           = 32'b0;
    manager_read_response       = 1'b1;
    manager_write_response      = 1'b1;
    for (i = 0; i < NUM_DEVICES; i = i + 1) begin
      if (device_sel_save[i]) begin
        manager_read_data       = device_read_data[i*32 +: 32];
        manager_read_response   = device_read_response[i];
        manager_write_response  = device_write_response[i];
      end
    end
  end

endmodule