//======================================================================
//
// test_core.v
// -----------
// A simple test core used during verification of the coretest test
// module. The test core provies a few read and write registers
// that can be tested. Additionally it also provides an 8-bit data
// port directly connected to one of the internal registers.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2014 SUNET
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or
// without modification, are permitted provided that the following
// conditions are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. 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.
//
// 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 OWNER 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.
//
//======================================================================
module test_core(
input wire clk,
input wire reset_n,
input wire cs,
input wire we,
input wire [7 : 0] address,
input wire [31 : 0] write_data,
output wire [31 : 0] read_data,
output wire error,
output wire [7 : 0] debug
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
// Programming interface
parameter ADDR_CORE_ID_0 = 8'h00;
parameter ADDR_CORE_ID_1 = 8'h01;
parameter ADDR_CORE_TYPE_0 = 8'h02;
parameter ADDR_CORE_TYPE_1 = 8'h03;
parameter ADDR_RW_REG = 8'h10;
parameter ADDR_DEBUG_REG = 8'h20;
parameter CORE_ID_0 = 32'h74657374; // "test"
parameter CORE_ID_1 = 32'h636f7265; // "core"
parameter CORE_TYPE_0 = 32'h30303030; // "00000"
parameter CORE_TYPE_1 = 32'h30303162; // "001b"
parameter RW_DEFAULT = 32'h11223344;
parameter DEBUG_DEFAULT = 8'h55;
//----------------------------------------------------------------
// Registers including update variables and write enable.
//----------------------------------------------------------------
reg [31 : 0] rw_reg;
reg [31 : 0] rw_new;
reg rw_we;
reg [7 : 0] debug_reg;
reg [7 : 0] debug_new;
reg debug_we;
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
reg tmp_error;
reg [31 : 0] tmp_read_data;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign error = tmp_error;
assign read_data = tmp_read_data;
assign debug = debug_reg;
//----------------------------------------------------------------
// reg_update
// Update functionality for all registers in the core.
// All registers are positive edge triggered with synchronous
// active low reset. All registers have write enable.
//----------------------------------------------------------------
always @ (posedge clk)
begin: reg_update
if (!reset_n)
begin
rw_reg <= RW_DEFAULT;
debug_reg <= DEBUG_DEFAULT;
end
else
begin
if (rw_we)
begin
rw_reg <= rw_new;
end
if (debug_we)
begin
debug_reg <= debug_new;
end
end
end // reg_update
//---------------------------------------------------------------
// read_write_logic
//
// Read and write register logic.
//---------------------------------------------------------------
always @*
begin: read_write_logic
// Defafult assignments
rw_new = 32'h00000000;
rw_we = 0;
debug_new = 8'h00;
debug_we = 0;
tmp_read_data = 32'h00000000;
tmp_error = 0;
if (cs)
begin
if (we)
begin
// Write operations.
case (address)
ADDR_RW_REG:
begin
rw_new = write_data;
rw_we = 1;
end
ADDR_DEBUG_REG:
begin
debug_new = write_data[7 : 0];
debug_we = 1;
end
default:
begin
tmp_error = 1;
end
endcase // case (address)
end
else
begin
// Read operations.
case (address)
ADDR_CORE_ID_0:
begin
tmp_read_data = CORE_ID_0;
end
ADDR_CORE_ID_1:
begin
tmp_read_data = CORE_ID_1;
end
ADDR_CORE_TYPE_0:
begin
tmp_read_data = CORE_TYPE_0;
end
ADDR_CORE_TYPE_1:
begin
tmp_read_data = CORE_TYPE_1;
end
ADDR_RW_REG:
begin
tmp_read_data = rw_reg;
end
ADDR_DEBUG_REG:
begin
tmp_read_data = {24'h000000, debug_reg};
end
default:
begin
tmp_error = 1;
end
endcase // case (address)
end
end
end // read_write_logic
endmodule // test_core
//======================================================================
// EOF test_core.v
//======================================================================
