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//======================================================================
//
// cipher_selector.v
// -----------------
// Top level wrapper that creates the Cryptech coretest system.
// The wrapper contains instances of external interface, coretest
// and the core to be tested. And if more than one core is
// present the wrapper also includes address and data muxes.
//
//
// Authors: Joachim Strombergson, Paul Selkirk, Pavel Shatov
// Copyright (c) 2014-2015, 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.
//
//======================================================================

module cipher_selector
        (
         input wire           sys_clk,
         input wire           sys_rst,
			input wire				sys_ena,

         input wire [13: 0]   sys_eim_addr,
         input wire           sys_eim_wr,
         input wire           sys_eim_rd,
         output wire [31 : 0] sys_read_data,
         input wire [31 : 0]  sys_write_data
        );


		//
		// Output Register
		//
	reg	[31: 0]	tmp_read_data;
	assign sys_read_data = tmp_read_data;
	

		/* So far we have no CIPHER cores, let's make some dummy 32-bit registers here
		 * to prevent ISE from complaining that we don't use input ports.
		 */
	 
	reg	[31: 0]	reg_dummy_first;
	reg	[31: 0]	reg_dummy_second;
	reg	[31: 0]	reg_dummy_third;
	
	always @(posedge sys_clk)
		//
		if (sys_rst) begin
			reg_dummy_first	<= {8{4'hD}};
			reg_dummy_second	<= {8{4'hE}};
			reg_dummy_third	<= {8{4'hF}};
		end else if (sys_ena) begin
			//
			if (sys_eim_wr) begin
				//
				// WRITE handler
				//
				case (sys_eim_addr)
					14'd0:	reg_dummy_first	<= sys_write_data;
					14'd1:	reg_dummy_second	<= sys_write_data;
					14'd2:	reg_dummy_third	<= sys_write_data;
				endcase
				//
			end
			//
			if (sys_eim_rd) begin
				//
				// READ handler
				//
				case (sys_eim_addr)
					14'd0:		tmp_read_data	<= reg_dummy_first;
					14'd1:		tmp_read_data	<= reg_dummy_second;
					14'd2:		tmp_read_data	<= reg_dummy_third;
					//
					default:		tmp_read_data	<= {32{1'b0}};	// read non-existent locations as zeroes
					/*
               default:		tmp_read_data	<= {32{1'bX}};	// don't care what to read from non-existent locations
					*/
				endcase
				//
			end
			//
		end
	

endmodule

//======================================================================
// EOF core_selector.v
//======================================================================