`timescale 1ns / 1ps

// ALICE/PHOS SRU
// Equivalent SRU = SRUV3FM2015071611_EMCal
// Fan Zhang. 16 July 2015

module srudcsreplyack
  (
	 input             reset,
	 input             dcsclk,

	 input             rcmd_reply_dv,
	 input [31:0]      udp_cmd_addr,
	 input [31:0]      rcmd_reply_data,

	 output reg        dcs_cmd_update = 1'b0,
	 output reg [63:0] dcs_cmd_reply = 64'h0
   );

  parameter st0 = 0; parameter st1 = 1;
  parameter st2 = 2; parameter st3 = 3;
  reg [1:0]          st = st0;

  always @(posedge dcsclk) begin
    if(reset) begin
      dcs_cmd_update <= 1'b0;
      dcs_cmd_reply <= 64'h0;
      st <= st0;
    end
    else begin
      case(st)
        st0 : begin
          dcs_cmd_update <= 1'b0;
          dcs_cmd_reply <= dcs_cmd_reply;

          if(rcmd_reply_dv)
            st <= st1;
          else
            st <= st0;
        end

        st1 : begin
          dcs_cmd_update <= 1'b0;
          dcs_cmd_reply <= {udp_cmd_addr,rcmd_reply_data};

          st <= st2;
        end

        st2 : begin
          dcs_cmd_update <= 1'b1;
          dcs_cmd_reply <= dcs_cmd_reply;

          st <= st3;
        end

        st3 : begin
          dcs_cmd_update <= 1'b0;
          dcs_cmd_reply <= dcs_cmd_reply;

          if(rcmd_reply_dv)
            st <= st3;
          else
            st <= st0;
        end

        default : begin
          dcs_cmd_update <= 1'b0;
          dcs_cmd_reply <= 64'h0;

          st <= st0;
        end
      endcase
    end // else: !if(reset)
  end // always @ (posedge dcsclk)

endmodule