module tb;

reg     clk = 1'b0;
always #`HALF_PERIOD clk = ~clk;

reg     rst = 1'b1;
initial #`PERIOD rst = 1'b0;

wire            rom_en;
wire [15:0]     rom_addr;
reg  [7:0]      rom_byte;
reg             rom_vld;

wire            ram_rd_en_data;
wire            ram_rd_en_sfr;
wire            ram_rd_en_xdata;
wire [15:0]     ram_rd_addr;

reg  [7:0]      ram_rd_byte;

wire            ram_wr_en_data;
wire            ram_wr_en_sfr;
wire            ram_wr_en_xdata;
wire [15:0]     ram_wr_addr;
wire [7:0]      ram_wr_byte;


r8051 u_cpu (
    .clk                  (    clk              ),
	.rst                  (    rst              ),
	.cpu_en               (    1'b1             ),
	.cpu_restart          (    1'b0             ),
	
	.rom_en               (    rom_en           ),
	.rom_addr             (    rom_addr         ),
	.rom_byte             (    rom_byte         ),
	.rom_vld              (    rom_vld          ),
	
	.ram_rd_en_data       (    ram_rd_en_data   ),
	.ram_rd_en_sfr        (    ram_rd_en_sfr    ),
	.ram_rd_en_xdata      (    ram_rd_en_xdata  ),
	.ram_rd_addr          (    ram_rd_addr      ),
	.ram_rd_byte          (    ram_rd_byte      ),
	.ram_rd_vld           (    1'b1             ),
	
	.ram_wr_en_data       (    ram_wr_en_data   ),
	.ram_wr_en_sfr        (    ram_wr_en_sfr    ),
	.ram_wr_en_xdata      (    ram_wr_en_xdata  ),
	.ram_wr_addr          (    ram_wr_addr      ),
	.ram_wr_byte          (    ram_wr_byte      )

);

reg [7:0] rom[(1'b1<<16)-1:0];

integer fd,fx;
initial begin
  fd = $fopen(`CODE_FILE,"rb");
  fx = $fread(rom,fd);
  $fclose(fd);
end
	
always @ ( posedge clk )
if ( rom_en )
    rom_byte <=  rom[rom_addr];
else;

always @ ( posedge clk )
rom_vld <=  rom_en;


reg [7:0] data [127:0];
reg [7:0] data_rd_byte;
always @ ( posedge clk )
if ( ram_rd_en_data )
    data_rd_byte <=  data[ram_rd_addr[6:0]];
else;

always @ ( posedge clk )
if ( ram_wr_en_data )
    data[ram_wr_addr[6:0]] <=  ram_wr_byte;
else;

reg [7:0] xdata [127:0];
reg [7:0] xdata_rd_byte;
always @ ( posedge clk )
if ( ram_rd_en_xdata )
    xdata_rd_byte <=  xdata[ram_rd_addr[6:0]];
else;

always @ ( posedge clk )
if ( ram_wr_en_xdata )
    if (( ram_wr_addr[6:0]==8'h7f ) & ram_wr_byte[0] ) begin
	    repeat(1000) @ (posedge clk);
		$display("Test over, simulation is OK!");
		$stop(1);
		end
	else
        xdata[ram_wr_addr[6:0]] <=  ram_wr_byte;
else;

reg [7:0] sfr_rd_byte;

always @ ( posedge clk )
if ( ram_wr_en_sfr & ( ram_wr_addr[7:0]==8'h99 ) )
    $write("%s",ram_wr_byte);
else;


always @ ( posedge clk )
if ( ram_rd_en_sfr ) 
    if ( ram_rd_addr[7:0]==8'h98 )
	    sfr_rd_byte <=  8'h3;
	else if ( ram_rd_addr[7:0]==8'h99 )
	    sfr_rd_byte <=  0;
	else
    begin
        $display($time," ns : --- SFR READ: %2h---",ram_rd_addr[7:0]);
        //$stop;
    end
else;	

always @ ( posedge clk )
if ( ram_wr_en_sfr )
    if(( ram_wr_addr[7:0]==8'h98 )|( ram_wr_addr[7:0]==8'h99 ))
	    #0;
    else	
    begin
    $display($time," ns : --- SFR WRITE: %2h -> %2h---",ram_wr_addr[7:0],ram_wr_byte);
    //$stop;
    end
else;	

reg [1:0] read_flag;
always @ ( posedge clk )
if ( ram_rd_en_sfr )
    read_flag <= 2'b10;
else if ( ram_rd_en_xdata )
    read_flag <= 2'b01;	
else if ( ram_rd_en_data )
    read_flag <= 2'b0;
else;

always @*
if ( read_flag[1] )
    ram_rd_byte = sfr_rd_byte;
else if ( read_flag[0] )
    ram_rd_byte = xdata_rd_byte;
else
    ram_rd_byte = data_rd_byte;

endmodule