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[/] [t6507lp/] [trunk/] [rtl/] [verilog/] [t2600_bus.v] - Rev 230
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//////////////////////////////////////////////////////////////////////////// //// //// //// t2600 IP Core //// //// //// //// This file is part of the t2600 project //// //// http://www.opencores.org/cores/t2600/ //// //// //// //// Description //// //// Bus controller for linking the t6507, t6532 and txxx. TODO //// //// //// //// TODO: //// //// - Nothing //// //// //// //// Author(s): //// //// - Gabriel Oshiro Zardo, gabrieloshiro@gmail.com //// //// - Samuel Nascimento Pagliarini (creep), snpagliarini@gmail.com //// //// //// //////////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2001 Authors and OPENCORES.ORG //// //// //// //// This source file may be used and distributed without //// //// restriction provided that this copyright statement is not //// //// removed from the file and that any derivative work contains //// //// the original copyright notice and the associated disclaimer. //// //// //// //// This source file is free software; you can redistribute it //// //// and/or modify it under the terms of the GNU Lesser General //// //// Public License as published by the Free Software Foundation; //// //// either version 2.1 of the License, or (at your option) any //// //// later version. //// //// //// //// This source is distributed in the hope that it will be //// //// useful, but WITHOUT ANY WARRANTY; without even the implied //// //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //// //// PURPOSE. See the GNU Lesser General Public License for more //// //// details. //// //// //// //// You should have received a copy of the GNU Lesser General //// //// Public License along with this source; if not, download it //// //// from http://www.opencores.org/lgpl.shtml //// //// //// //////////////////////////////////////////////////////////////////////////// `include "timescale.v" module t2600_bus(address, data_from_cpu, cpu_rw_mem, riot_data, rom_data, tia_data, address_riot, address_rom, address_tia, data_to_cpu, enable_riot, enable_rom, enable_tia, rw_mem); parameter [3:0] DATA_SIZE = 4'd8; parameter [3:0] ADDR_SIZE = 4'd13; localparam [3:0] DATA_SIZE_ = DATA_SIZE - 4'd1; localparam [3:0] ADDR_SIZE_ = ADDR_SIZE - 4'd1; localparam [3:0] RIOT_ADDR_SIZE_ = 4'd6; localparam [3:0] TIA_ADDR_SIZE_ = 4'd5; input [ADDR_SIZE_:0] address; input [DATA_SIZE_:0] data_from_cpu; input cpu_rw_mem; inout [DATA_SIZE_:0] riot_data; inout [DATA_SIZE_:0] rom_data; inout [DATA_SIZE_:0] tia_data; output reg [RIOT_ADDR_SIZE_:0] address_riot; output reg [ADDR_SIZE_:0] address_rom; output reg [TIA_ADDR_SIZE_:0] address_tia; output reg[DATA_SIZE_:0] data_to_cpu; output reg enable_riot; output reg enable_rom; output reg enable_tia; output reg rw_mem; assign riot_data = (rw_mem) ? data_from_cpu : 8'bZ; // if i am writing the bus receives the data from cpu assign rom_data = (rw_mem) ? data_from_cpu : 8'bZ; // if i am writing the bus receives the data from cpu assign tia_data = (rw_mem) ? data_from_cpu : 8'bZ; // if i am writing the bus receives the data from cpu always @(*) begin enable_riot = 1'b0; enable_rom = 1'b0; enable_tia = 1'b0; rw_mem = cpu_rw_mem; address_tia = address[5:0]; address_riot = address[6:0]; address_rom = address; if (address[12]) begin data_to_cpu = rom_data; enable_rom = 1'b1; end else if (address[7]) begin data_to_cpu = riot_data; enable_riot = 1'b1; end else begin data_to_cpu = tia_data; enable_tia = 1'b1; end end endmodule
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