三位元全加法器 結構

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

一位元全加法器 卡諾圖

module top;

wire Cin,A,B,Cout,Sum;

system_clock #400 clock1(Cin); 

system_clock #200 clock2(A);

system_clock #100 clock3(B);

adder1 M1(Cout, Sum, A, B, Cin);

endmodule

module adder1(Cout, Sum, A, B, Cin);

output Cout,Sum;

input A,B,Cin;

and I1 (AandB, A, B);

xor I2 (AxorB, A, B);

and I3 (And1, AxorB, Cin);

or I4 (Cout, AandB, And1);

xor I5 (Sum, AxorB, Cin);

endmodule

module system_clock(clk); 

parameter PERIOD=100; 

output clk; 

reg clk; 

initial clk=0; 

always 

 begin 

#(PERIOD/2) clk=~clk; 

 end 

always@(posedge clk)

 if($time>1000)$stop; 

endmodule 

一位元全加法器

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

一位元

module top;

integer ia,ib,is;

reg  a,b,s;

wire out;

mux_behavioral mux1(out,a,b,s);

initial

begin

for (ia=0; ia<=1; ia = ia+1)

begin

a = ia;

for (ib=0; ib<=1; ib = ib + 1)

begin

b = ib;

for (is=0; is<=1; is = is + 1)

begin

s = is;

#1 $display("a=%d b=%d s=%d   out=%d",a,b,s,out);

end

end

end

end

endmodule

module mux_behavioral(OUT, A, B, SEL);

 output OUT;

 input A,B,SEL;

 wire  A,B,SEL;

 reg    OUT;

  always @(A or B or SEL)

   OUT = (A & SEL)|(B & ~SEL );

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

2+2位元=4位元

module top; 

wire [3:0]OUT, A, B;

wire SEL;

system_clock #12800 clock1(A[3]); 

system_clock #6400 clock2(A[2]); 

system_clock #3200 clock3(A[1]);

system_clock #1600 clock4(A[0]);

system_clock #800 clock5(B[3]);

system_clock #400 clock6(B[2]);

system_clock #200 clock7(B[1]);

system_clock #100 clock8(B[0]);

system_clock #25600 clock7(SEL);

mux2 m1(OUT[1:0],A[1:0],B[1:0],SEL);

mux2 m2(OUT[3:2],A[3:2],B[3:2],SEL);

endmodule 

module mux(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

module mux2(OUT, A, B, SEL);

output [1:0] OUT;

input [1:0] A,B;

input SEL;

mux hi (OUT[1], A[1], B[1], SEL);

mux lo (OUT[0], A[0], B[0], SEL);

endmodule

module system_clock(clk);

parameter PERIOD=100;

output clk;

reg clk;

initial clk=0;

always

begin

#(PERIOD/2) clk=~clk;

end

always@(posedge clk)

 if($time>25600)$stop;

endmodule 

1位元加上2位元組成3位元

module top;

wire [2:0]OUT, A, B;

wire SEL;

system_clock #3200 clock1(A[2]);

system_clock #1600 clock2(A[1]);

system_clock #800 clock3(A[0]);

system_clock #400 clock4(B[2]);

system_clock #200 clock5(B[1]);

system_clock #100 clock6(B[0]);

system_clock #6400 clock7(SEL);

mux m1(OUT[0],A[0],B[0],SEL);

mux2 m2(OUT[2:1],A[2:1],B[2:1],SEL);

endmodule

module mux(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

module mux2(OUT, A, B, SEL);

output [1:0] OUT;

input [1:0] A,B;

input SEL;

mux hi (OUT[1], A[1], B[1], SEL);

mux lo (OUT[0], A[0], B[0], SEL);

endmodule

module system_clock(clk);

parameter PERIOD=100;

output clk;

reg clk;

initial clk=0;

always

begin

#(PERIOD/2) clk=~clk;

end

always@(posedge clk)

 if($time>6400)$stop;

endmodule