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//======================================================================
//
// terasic_regs.v
// -------------
// Global registers for the Cryptech Terasic FPGA framework.
//
//
// Author: Pavel Shatov
// Copyright (c) 2015, NORDUnet A/S All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
// be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//======================================================================
`timescale 1ns / 1ps
module board_regs
(
input wire clk,
input wire rst,
input wire cs,
input wire we,
input wire [ 7 : 0] address,
input wire [31 : 0] write_data,
output wire [31 : 0] read_data
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
// API addresses.
localparam ADDR_CORE_NAME0 = 8'h00;
localparam ADDR_CORE_NAME1 = 8'h01;
localparam ADDR_CORE_VERSION = 8'h02;
localparam ADDR_DUMMY_REG = 8'hFF; // general-purpose register
// Core ID constants.
localparam CORE_NAME0 = 32'h54433547; // "TC5G"
localparam CORE_NAME1 = 32'h20202020; // " "
localparam CORE_VERSION = 32'h302e3130; // "0.10"
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
reg [31: 0] tmp_read_data;
// dummy register to check that you can actually write something
reg [31: 0] reg_dummy;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign read_data = tmp_read_data;
//----------------------------------------------------------------
// Access Handler
//----------------------------------------------------------------
always @(posedge clk)
//
if (rst)
reg_dummy <= {32{1'b0}};
else if (cs) begin
//
if (we) begin
//
// WRITE handler
//
case (address)
ADDR_DUMMY_REG:
reg_dummy <= write_data;
endcase
//
end else begin
//
// READ handler
//
case (address)
ADDR_CORE_NAME0:
tmp_read_data <= CORE_NAME0;
ADDR_CORE_NAME1:
tmp_read_data <= CORE_NAME1;
ADDR_CORE_VERSION:
tmp_read_data <= CORE_VERSION;
ADDR_DUMMY_REG:
tmp_read_data <= reg_dummy;
//
default:
tmp_read_data <= {32{1'b0}}; // read non-existent locations as zeroes
endcase
//
end
//
end
endmodule
//======================================================================
// EOF terasic_regs.v
//======================================================================
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