module yunsuan1(input clk,rst_n,output reg [7:0]a,b,b1,b2,b3,c,d,count);
always @(posedge clk)
begin
count=count+1;
if(count==10) a=-25;
if(count==11) a=-26;
if(count==12) a=25;
if(count==13) a=2;
b=~a+1;
b1=b>>1;
b2=~b1+1;
if(a[0])b3=~b1;else b3=~b1+1;
end
endmodule
可以看出负数补码分为奇数和偶数表示：-25和-26的补码都为-13.