//
// Copyright 2011 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

`timescale 1ps/1ps

module gpmc_model_async
  (output EM_CLK, inout [15:0] EM_D, output reg [10:1] EM_A, output reg [1:0] EM_NBE,
   output reg EM_WAIT0, output reg EM_NCS4, output reg EM_NCS6, 
   output reg EM_NWE, output reg EM_NOE );

   assign EM_CLK = 0;
   reg [15:0] EM_D_int;
   assign EM_D = EM_D_int;
   
   initial
     begin
	EM_A <= 10'bz;
	EM_NBE <= 2'b11;
	EM_NWE <= 1;
	EM_NOE <= 1;
	EM_NCS4 <= 1;
	EM_NCS6 <= 1;
	EM_D_int <= 16'bz;
 	EM_WAIT0 <= 0;  // FIXME this is actually an input
     end
   
   task GPMC_Write;
      input ctrl;
      input [10:0] addr;
      input [15:0] data;
      begin
	 #23000;
	 EM_A <= addr[10:1];
	 EM_D_int <= data;
	 #20100;
	 if(ctrl)
	   EM_NCS6 <= 0;
	 else
	   EM_NCS4 <= 0;
	 #14000;
	 EM_NWE <= 0;
	 #77500;
	 EM_NCS4 <= 1;
	 EM_NCS6 <= 1;
	 //#1.5;
	 EM_NWE <= 1;
	 #60000;
	 EM_A <= 10'bz;
	 EM_D_int <= 16'bz;
      end
   endtask // GPMC_Write

   task GPMC_Read;
      input ctrl;
      input [10:0] addr;
      begin
	 #13000;
	 EM_A <= addr[10:1];
	 #3000;
	 if(ctrl)
	   EM_NCS6 <= 0;
	 else
	   EM_NCS4 <= 0;
	 #14000;
	 EM_NOE <= 0;
	 #77500;
	 EM_NCS4 <= 1;
	 EM_NCS6 <= 1;
	 //#1.5;
	 $display("Data Read from GPMC: %X",EM_D);
	 EM_NOE <= 1;
	 #254000;
	 EM_A <= 10'bz;
      end
   endtask // GPMC_Read
   
   initial
     begin
	#1000000;
	GPMC_Write(1,36,16'hF00D);
	#1000000;
	GPMC_Read(1,36);
	#1000000;
	GPMC_Write(0,0,16'h1234);
	GPMC_Write(0,0,16'h5678);
	GPMC_Write(0,0,16'h9abc);
	GPMC_Write(0,0,16'hF00D);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	#1000000;
	GPMC_Write(0,0,16'h1234);
	GPMC_Write(0,0,16'h5678);
	GPMC_Write(0,0,16'h9abc);
	GPMC_Write(0,0,16'hF00D);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'hDEAD);
	GPMC_Write(0,0,16'h9876);
	#1000000;
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	#1000000;
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	GPMC_Read(0,0);
	#1000000;
	GPMC_Read(0,0);
	#100000000;
	$finish;
     end
   
endmodule // gpmc_model_async