P6-22 4bit 比較器適用於DE2-70

P6-22 4bit 比較器適用於DE2-70

//-----------------------------------------
// 4-bit Comparator with asynchronous reset
// (if...else if...else)
// Filename: comp4_if.v
//-----------------------------------------
module _4bit_comp(SW, LEDR, LEDG , CLOCK_27 ,KEY );

input  [17:0] SW; // toggle switches
input  [7:0] KEY;     // Push bottom
input  CLOCK_27; //Clock 27MHz , 50Mhz

output [17:0] LEDR; // red  LEDS   
  output [7:0] LEDG; // green LEDs
  
  
//set original program input , output 

    // Port Declarations
    // output eq, gt, lt;  //outputs eq:Equal, gt:Great than, lt:Less than
    // input [3:0] a, b; //4-bit inputs
    wire [3:0] a,b;
    reg eq, gt, lt;

    
    //mapping to hardware 
    assign LEDR = SW;
    
    assign a=SW[3:0]; 
    assign b=SW[7:4];
      
always @ (a or b)
begin
if (a==b)
begin
eq = 1'b1; gt = 1'b0; lt = 1'b0;
end
else if (a > b)
begin
eq = 1'b0; gt = 1'b1; lt = 1'b0;
end
else
begin
eq = 1'b0; gt = 1'b0; lt = 1'b1;
end
end

assign LEDG[0]=lt;
assign LEDG[1]=eq;
assign LEDG[2]=gt;


endmodule