// nandgame arithmetic unit

`timescale 1us/1us

`include "nandgame_types.v"

`ifndef NANDGAME_ARU
`define NANDGAME_ARU

module  arith_unit #(
  parameter DATA_WIDTH = 16
) (
  // first operand
  input [(DATA_WIDTH-1):0] X_in,
  // second operand
  input [(DATA_WIDTH-1):0] Y_in,
  // opcode, see ArithCode
  input ArithCode arith_operation_in,

  // result of operation
  output logic [(DATA_WIDTH-1):0] result_out
);

always_comb begin
    case (arith_operation_in)
        ARITH_PLUS: result_out = X_in + Y_in;
        ARITH_MINUS:  result_out = X_in - Y_in;
        ARITH_INC: result_out = X_in + 1;
        ARITH_DEC: result_out = X_in - 1;
        default: result_out = 0;
    endcase
end

endmodule

`endif