//2023-10-12 姜青羊
//补码转换练习

/*`timescale 1ns/10ps
module comp_conv (
                    a,
                    a_comp
                 );

input[7:0]          a;
output[7:0]         a_comp;

wire[6:0]           b;
wire[7:0]           y;

assign              b = ~a[6:0];
assign              y[6:0] = b+1; 
assign              y[7] = a[7];

assign              a_comp = a[7]?y:a;
    
endmodule
*/

/*
//把b变量去掉
`timescale 1ns/10ps
module comp_conv (
                    a,
                    a_comp
                 );

input[7:0]          a;
output[7:0]         a_comp;

wire[7:0]           y;

assign              y[6:0] = ~a[6:0]+1; 
assign              y[7] = a[7];

assign              a_comp = a[7]?y:a;
    
endmodule
*/

//把38、39合成一句来写，用拼接的方式

`timescale 1ns/10ps
module comp_conv (
                    a,
                    a_comp
                 );

input[7:0]          a;
output[7:0]         a_comp;

wire[7:0]           y;

//assign              y[6:0] = ~a[6:0]+1; 
//assign              y[7] = a[7];

assign                y = {a[7],~a[6:0]+1};

assign              a_comp = a[7]?y:a;   //这里还能简洁，连y都不用   a_comp = a[7]?{a[7],~a[6:0]+1}:a;
    
endmodule

//-------testbench of comp_conv------

module tb_comp_conv ();

reg[7:0]             a_in;
wire[7:0]            y_out;

initial begin
                  a_in <= 0;
         #3000    $stop;
end

always  #10      a_in = a_in+1;

comp_conv u_comp_conv (
                    .a(a_in),
                    .a_comp(y_out)
                 );
   
endmodule