Program_Counter

module ProgCounter(PC, PC_in, PS, in, clock,reset); input [1:0] PS; input [63:0]in; input clock, reset; output reg [63:0] PC; output [63:0] PC_in;

wire [63:0] PC4 = PC + 64'd4;
wire load = PS[0] | PS[1];

assign PC_in = PC4;

always @(posedge clock or posedge reset) begin if (reset) begin PC = 64'd0; end

else if (load) begin
case(PS)
// Program Counter is incremented by four	
	2'b01: PC = PC4;
// Program Counter is incremented by a specified value
	2'b10: PC = in;
// Program Counter is increment by four  plus a specified value times 4
	2'b11: PC = PC4 + in*64'd4;	
endcase
end

else begin
// Program Counter is constant
	PC = PC;
end

end

endmodule