vivado 有符号数的相加_vivado滑窗相加

module top(
input signed [2:0] a,
input signed [2:0] b,
output signed [3:0] out
    );
        assign out=a+b;
endmodule

module tb(
 
    );
    reg signed [2:0]a;
    reg signed [2:0]b;
    wire signed [3:0]out;
    initial begin
    a=-2; b=-4;
    #20 a=3;b=3;
    #30 a=-4;b=3;
    #10 a=-2;b=3;
    #20 a=-4;b=-4;
    #10 a=-3;
    #50 a=4;           //无效的 依然为-4 但不会报错
    end
    top tbtop(a,b,out);
endmodule