//
// Title      : (153) DUAL 4-LINE TO 1LINE DATA SELECTORS/MULTIPLEXERS
// File name  : 153.v
// Date       : 2000/12/08  Ver1.0
// Company    : Future Technology Ltd.
//

//----------------------------------------------------------
//  Module
//----------------------------------------------------------

module U153(
            A,
            B,
            C1,
            C2,
            XG1,
            XG2,
            Y1,
            Y2
        );

    input           A;
    input           B;
    input   [3:0]   C1;
    input   [3:0]   C2;
    input           XG1;
    input           XG2;
    output          Y1;
    output          Y2;

//----------------------------------------------------------
//  Using register
//----------------------------------------------------------
    reg             Y1;
    reg             Y2;
//----------------------------------------------------------
//  Using wire
//----------------------------------------------------------
    wire    [1:0]   s_ba;


    assign s_ba = {B,A};

    always@(s_ba or C1 or XG1)begin
        if(XG1==1'b1)begin              // G = 1
            Y1 = 1'b0;
        end else begin                  // G != 1
            case(s_ba[1:0])
                2'b00   :   Y1 = C1[0];
                2'b01   :   Y1 = C1[1];
                2'b10   :   Y1 = C1[2];
                2'b11   :   Y1 = C1[3];
                default :   Y1 = 1'bx;
            endcase
        end
    end

    always@(s_ba or C2 or XG2)begin
        if(XG2==1'b1)begin              // G = 1
            Y2 = 1'b0;
        end else begin                  // G != 1
            case(s_ba[1:0])
                2'b00   :   Y2 = C2[0];
                2'b01   :   Y2 = C2[1];
                2'b10   :   Y2 = C2[2];
                2'b11   :   Y2 = C2[3];
                default :   Y2 = 1'bx;
            endcase
        end
    end

endmodule