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//------------------------------
// Module name: add3_ge5
// Function: Add 3 to input if it is 5 or above
// Creator: Peter Cheung
// Version: 1.0
// Date: 21 Jan 2014
//------------------------------
module add3_ge5(w,a);
input [3:0] w;
output [3:0] a;
reg [3:0] a;
always @ (w)
case (w)
4'b0000: a <= 4'b0000;
4'b0001: a <= 4'b0001;
4'b0010: a <= 4'b0010;
4'b0011: a <= 4'b0011;
4'b0100: a <= 4'b0100;
4'b0101: a <= 4'b1000;
4'b0110: a <= 4'b1001;
4'b0111: a <= 4'b1010;
4'b1000: a <= 4'b1011;
4'b1001: a <= 4'b1100;
4'b1010: a <= 4'b1101;
4'b1011: a <= 4'b1110;
4'b1100: a <= 4'b1111;
default: a <= 4'b0000; // a cannot be 13 or larger, else overflow
endcase
endmodule
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