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module ex4_top (
input [9:0] SW,
output [6:0] HEX0,
output [6:0] HEX1,
output [6:0] HEX2,
output [6:0] HEX3
);
reg [3:0] BCD0;
reg [3:0] BCD1;
reg [3:0] BCD2;
reg [3:0] BCD3;
integer i;
always @ (*)
begin
BCD0 = 4'd0;
BCD1 = 4'd0;
BCD2 = 4'd0;
BCD3 = 4'd0;
for (i=9; i>=0; i=i-1)
begin
if (BCD3 >= 5)
BCD3 = BCD3 +3;
if (BCD2 >= 5)
BCD2 = BCD2 +3;
if (BCD1 >= 5)
BCD1 = BCD1 +3;
if (BCD0 >= 5)
BCD0 = BCD0 +3;
// shift each digit
BCD3 = BCD3 << 1;
BCD3[0] = BCD2[3];
BCD2 = BCD2 << 1;
BCD2[0] = BCD1[3];
BCD1 = BCD1 << 1;
BCD1[0] = BCD0[3];
BCD0 = BCD0 << 1;
BCD0[0] = SW[i];
end
end
hex_to_7seg SEG3 (HEX3, BCD3);
hex_to_7seg SEG2 (HEX2, BCD2);
hex_to_7seg SEG1 (HEX1, BCD1);
hex_to_7seg SEG0 (HEX0, BCD0);
endmodule
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