P5-33 1bit減法器 適用於DE2-70 實驗板

module Sub1bits (SW, LEDR, LEDG);

input [17:0] SW; // toggle switches

output [17:0] LEDR; // red  LEDS   

  output [7:0] LEDG; // green LEDs

  

//set original program input , output 

wire X, Y, Bin;

wire  Dif, Bout;

   

    //mapping to hardware 

    assign LEDR = SW;

    //assign SW to input 

    assign X=SW[2];

    assign Y=SW[1];

    assign Bin=SW[0];

    

    //  X - Y -Bin = Bout , Dif       

//Assign difference and borrow

assign Dif = (((~X)&(~Y)&Bin)|((~X)&(Y)&(~Bin))|(X&(~Y)&(~Bin))|(X & Y & Bin));

assign Bout = (((~X)&Y)|((~X)&Bin)|(Y & Bin));

    assign LEDG[0]=Dif;

    assign LEDG[1]=Bout;

endmodule

/*original program

//-------------------------------------

//Filename : fadd1_df.v

//-------------------------------------

module fadd1_df(X, Y, Bin, Dif, Bout);

input X, Y, Bin;

output Dif, Bout;

//Assign difference and borrow

assign Dif = (((~X)&(~Y)&Bin)|((~X)&(Y)&(~Bin))|(X&(~Y)&(~Bin))|(X & Y & Bin));

assign Bout = (((~X)&Y)|((~X)&Bin)|(Y & Bin));

endmodule

*/