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標題: 有號數的加法 [列印本頁]

作者: mm117777 時間: 2012-7-4 08:53:24 標題: 有號數的加法

式：sadd4.v
module fulladder (input a, b, c_in, output sum, c_out);
wire s1, c1, c2;

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 adder4(input signed [3:0] a, input signed [3:0] b, input c_in, output signed [3:0] sum, output c_out);
wire [3:0] c;

fulladder fa1(a[0],b[0], c_in, sum[0], c[1]) ;
fulladder fa2(a[1],b[1], c[1], sum[1], c[2]) ;
fulladder fa3(a[2],b[2], c[2], sum[2], c[3]) ;
fulladder fa4(a[3],b[3], c[3], sum[3], c_out) ;

endmodule

module main;
reg signed [3:0] a;
reg signed [3:0] b;
wire signed [3:0] sum;
wire c_out;

adder4 DUT (a, b, 1'b0, sum, c_out);

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
Icarus 編譯執行
D:\ccc101\icarus\ccc>iverilog -o sadd4 sadd4.v

D:\ccc101\icarus\ccc>vvp sadd4
      50ns monitor: a= 5 b= 1 sum= 6
   100ns monitor: a= 5 b= 2 sum= 7
   150ns monitor: a= 5 b= 3 sum=-8
   200ns monitor: a= 5 b= 4 sum=-7
   250ns monitor: a= 5 b= 5 sum=-6
   300ns monitor: a= 5 b= 6 sum=-5
   350ns monitor: a= 5 b= 7 sum=-4
   400ns monitor: a= 5 b=-8 sum=-3
   450ns monitor: a= 5 b=-7 sum=-2
   500ns monitor: a= 5 b=-6 sum=-1
   550ns monitor: a= 5 b=-5 sum= 0
   600ns monitor: a= 5 b=-4 sum= 1
   650ns monitor: a= 5 b=-3 sum= 2
   700ns monitor: a= 5 b=-2 sum= 3
   750ns monitor: a= 5 b=-1 sum= 4
   800ns monitor: a= 5 b= 0 sum= 5
   850ns monitor: a= 5 b= 1 sum= 6
   900ns monitor: a= 5 b= 2 sum= 7
   950ns monitor: a= 5 b= 3 sum=-8
   1000ns monitor: a= 5 b= 4 sum=-7
   1050ns monitor: a= 5 b= 5 sum=-6
   1100ns monitor: a= 5 b= 6 sum=-5
   1150ns monitor: a= 5 b= 7 sum=-4
   1200ns monitor: a= 5 b=-8 sum=-3
   1250ns monitor: a= 5 b=-7 sum=-2
   1300ns monitor: a= 5 b=-6 sum=-1
   1350ns monitor: a= 5 b=-5 sum= 0
   1400ns monitor: a= 5 b=-4 sum= 1
   1450ns monitor: a= 5 b=-3 sum= 2
   1500ns monitor: a= 5 b=-2 sum= 3
   1550ns monitor: a= 5 b=-1 sum= 4
   1600ns monitor: a= 5 b= 0 sum= 5
   1650ns monitor: a= 5 b= 1 sum= 6
   1700ns monitor: a= 5 b= 2 sum= 7
   1750ns monitor: a= 5 b= 3 sum=-8
   1800ns monitor: a= 5 b= 4 sum=-7
   1850ns monitor: a= 5 b= 5 sum=-6
   1900ns monitor: a= 5 b= 6 sum=-5
   1950ns monitor: a= 5 b= 7 sum=-4
   2000ns monitor: a= 5 b=-8 sum=-3
無號數的加法
程式：adder4.v
module fulladder (input a, b, c_in, output sum, c_out);
wire s1, c1, c2;

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 adder4(input [3:0] a, input [3:0] b, input c_in, output [3:0] sum, output c_out);
wire [3:0] c;

fulladder fa1(a[0],b[0], c_in, sum[0], c[1]) ;
fulladder fa2(a[1],b[1], c[1], sum[1], c[2]) ;
fulladder fa3(a[2],b[2], c[2], sum[2], c[3]) ;
fulladder fa4(a[3],b[3], c[3], sum[3], c_out) ;

endmodule

module main;
reg [3:0] a;
reg [3:0] b;
wire [3:0] sum;
wire c_out;

adder4 DUT (a, b, 1'b0, sum, c_out);

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
Icarus 編譯執行
D:\ccc101\icarus\ccc>iverilog -o adder4 adder4.v

D:\ccc101\icarus\ccc>vvp adder4
      50ns monitor: a= 5 b= 1 sum= 6
   100ns monitor: a= 5 b= 2 sum= 7
   150ns monitor: a= 5 b= 3 sum= 8
   200ns monitor: a= 5 b= 4 sum= 9
   250ns monitor: a= 5 b= 5 sum=10
   300ns monitor: a= 5 b= 6 sum=11
   350ns monitor: a= 5 b= 7 sum=12
   400ns monitor: a= 5 b= 8 sum=13
   450ns monitor: a= 5 b= 9 sum=14
   500ns monitor: a= 5 b=10 sum=15
   550ns monitor: a= 5 b=11 sum= 0
   600ns monitor: a= 5 b=12 sum= 1
   650ns monitor: a= 5 b=13 sum= 2
   700ns monitor: a= 5 b=14 sum= 3
   750ns monitor: a= 5 b=15 sum= 4
   800ns monitor: a= 5 b= 0 sum= 5
   850ns monitor: a= 5 b= 1 sum= 6
   900ns monitor: a= 5 b= 2 sum= 7
   950ns monitor: a= 5 b= 3 sum= 8
   1000ns monitor: a= 5 b= 4 sum= 9
   1050ns monitor: a= 5 b= 5 sum=10
   1100ns monitor: a= 5 b= 6 sum=11
   1150ns monitor: a= 5 b= 7 sum=12
   1200ns monitor: a= 5 b= 8 sum=13
   1250ns monitor: a= 5 b= 9 sum=14
   1300ns monitor: a= 5 b=10 sum=15
   1350ns monitor: a= 5 b=11 sum= 0
   1400ns monitor: a= 5 b=12 sum= 1
   1450ns monitor: a= 5 b=13 sum= 2
   1500ns monitor: a= 5 b=14 sum= 3
   1550ns monitor: a= 5 b=15 sum= 4
   1600ns monitor: a= 5 b= 0 sum= 5
   1650ns monitor: a= 5 b= 1 sum= 6
   1700ns monitor: a= 5 b= 2 sum= 7
   1750ns monitor: a= 5 b= 3 sum= 8
   1800ns monitor: a= 5 b= 4 sum= 9
   1850ns monitor: a= 5 b= 5 sum=10
   1900ns monitor: a= 5 b= 6 sum=11
   1950ns monitor: a= 5 b= 7 sum=12
   2000ns monitor: a= 5 b= 8 sum=13

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