一位元加法器行為模式設計與測試

module test_adder1;

 reg a,b;
 reg carry_in ; 
 wire sum;
 wire carry_out;

 adder1_behavorial A1(carry_out, sum, a, b, carry_in);

 initial 
  begin

   

    carry_in = 0; a = 0; b = 0; 
    # 100 if ( carry_in != 0 | sum !== 0) 
                $display(" 0+0+0=00 sum is WRONG!");
              else
                $display(" 0+0+0=00 sum is RIGHT!");
    carry_in = 0; a = 0; b = 1; 
    # 100 if ( carry_in != 0 | sum !== 1) 
               $display(" 0+0+1=01 sum is WRONG!");
              else
               $display(" 0+0+1=01 sum is RIGHT!");
    carry_in = 0; a = 1; b = 0; 
    # 100 if ( carry_in != 0 | sum !== 1) 
               $display(" 0+1+0=01 sum is WRONG!");
              else
               $display(" 0+1+0=01 sum is RIGHT!");
    carry_in = 0; a = 1; b = 1; 
    # 100 if ( carry_in != 1 | sum !== 0) 
               $display(" 0+1+1=10 sum is WRONG!");
              else
               $display(" 0+1+1=10 sum is RIGHT!");
    carry_in = 1; a = 0; b = 0; 
    # 100 if ( carry_in != 0 | sum !== 1) 
               $display(" 1+0+0=01 sum is WRONG!");
              else
               $display(" 1+0+0=01 sum is RIGHT!");
     carry_in = 1; a = 0; b = 1; 
    # 100 if ( carry_in != 1 | sum !== 0) 
               $display(" 1+0+1=10 sum is WRONG!");
              else
               $display(" 1+0+1=10 sum is RIGHT!");
    carry_in = 1; a = 1; b = 0; 
    # 100 if ( carry_in != 1 | sum !== 0) 
               $display(" 1+1+0=10 sum is WRONG!");
              else
               $display(" 1+1+0=10 sum is RIGHT!");
    carry_in = 1; a = 1; b = 1; 
    # 100 if ( carry_in != 1 | sum !== 1) 
               $display(" 1+1+1=11 sum is WRONG!");
              else
               $display(" 1+1+1=11 sum is RIGHT!");

    $finish;
  end
endmodule



module adder1_behavorial (carry_out, sum, a, b, carry_in);
 input a, b, carry_in;
 output carry_out, sum;
  assign sum = (~a&b&~carry_in)|(~carry_in&a&~b)|(a&b&carry_in); 
  assign carry_out = a&carry_in|a&b|b&carry_in; 
endmodule