11/25三位元全加法

module fulladder (sum, c_out, a, b, c_in);
wire s1, c1, c2;
output sum;
output c_out;
input a, b, c_in;
xor g1(s1, a, b);
xor g2(sum, s1, c_in);
and g3(c1, a,b);
and g4(c2, s1, c_in) ;
xor g5(c_out, c2, c1) ;

endmodule

module adder3(sum, c_out, a, b, c_in);
wire [2:0] c;
output [2:0] sum;
output c_out;
input [2:0] a;
input [2:0] b;
input c_in;
fulladder fa1(sum[0], c[1], a[0], b[0], c_in) ;
fulladder fa2(sum[1], c[2], a[1], b[1], c[1]) ;
fulladder fa3(sum[2], c_out, a[2], b[2], c[2]) ;


endmodule

module main;
reg [2:0] a;
reg [2:0] b;
wire [2:0] sum;
wire c_out;

adder3 DUT (sum, c_out, a, b, 1'b0);

initial
begin
  a = 4'b0101;
  b = 4'b0000;
end

always #50 begin
  b=b+1;
  $monitor("%dns monitor: a=%d b=%d sum=%d", $stime, a, b, sum);
end

initial #2000 $finish;

endmodule

11/18解b*g

11/18 B*G

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 = 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


no.2

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
                                                                                                                                                                                 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 = 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)|(~a~b&carry_in);
  assign carry_out = a&carry_in|a&b|b&carry_in;
endmodule

11/4二位元

....

module top;
  integer ia,ib,is;
  reg  a,b,s;
  wire out;

  mux_structural mux1(out,a,b,s);

initial
 begin
for (is=0; is<=1; is = is + 1)
 begin
 s = is;

 for (ia=0; ia<=1; ia = ia+1)
 begin
 a = ia;
 for (ib=0; ib<=1; ib = ib + 1)
 begin
 b = ib;
 #1 $display("a=%d b=%d s=%d   out=%d",a,b,s,out);
 end
 end
 end
 end
 endmodule

 module mux_structural(OUT, A, B, SEL);
 output OUT;
 input A,B,SEL;
 not I5 (sel_n, SEL);
 and I6 (sel_a, A, SEL);
 and I7 (sel_b, sel_n, B);
 or I4 (OUT, sel_a, sel_b);
endmodule
二位元:
module top;
  integer is;
  integer ia[1:0],ib[1:0];
  reg [1:0]a,b;
  reg s;
  wire [1:0]out;

  mux_behavioral mux2(out,a,b,s);

  initial
    begin
      for (is=0; is<=1; is = is + 1)
       begin
        s = is;
         for (ia[0]=0; ia[0]<=1; ia[0] = ia[0]+1)
          begin
           a[0]= ia[0];
            for (ia[1]=0; ia[1]<=1; ia[1] = ia[1]+ 1)
             begin
              a[1] = ia[1];
               for (ib[0]=0; ib[0]<=1; ib[0] = ib[0]+1)
                 begin
                   b[0] = ib[0];
                    for (ib[1]=0; ib[1]<=1; ib[1] = ib[1]+ 1)
                     begin
                      b[1] = ib[1];
                 #1 $display("a[0]=%d a[1]=%d b[0]=%d b[1]=%d s=%d out[0]%d out[1]%d",a[0],a[1],b[0],b[1],s,out[0],out[1]);
                      end
                    end
                  end
              end
         end
    end
endmodule

module mux_behavioral(OUT,A,B,SEL);
 output [1:0]OUT;
 input [1:0] A,B;
 input SEL;

mux1 X1(OUT[0],A[0],B[0],SEL);
mux1 X2(OUT[1],A[1],B[1],SEL);

endmodule

module mux1(OUT, A, B, SEL);
 output OUT;
 input A,B,SEL;

 not n1(NOT_SEL, SEL);
 and a1 (X, A, NOT_SEL);
 and a2 (Y, SEL, B);
 or  o1 (OUT, X, Y);

endmodule

11/4改錯