8bit x 8bit 乘法器 適用於DE2-70

8bit x 8bit 乘法器

module _8x8bit_mul(SW,LEDR);
input [15:0]SW;
output [15:0]LEDR;

wire [7:0]a0,b0;

assign a0=SW[7:0];
assign b0=SW[15:8];
 mult8S U0(LEDR[15:0],a0,b0);

endmodule


// ------------------------------------------------------------------------
//8-bit multiplier
//Filename : mult16S.v : P = A * B 
//-------------------------------------------------------------------------
module mult8S(P,A,B);
output [15:0]P; // 32-bit product

input [7:0]A; //Multiplicand
input [7:0]B; //Multiplier

reg [15:0] p;
reg [15:0] temp;
reg [7:0] a;
reg [7:0] b;
integer  i;

always @(A or B)
   begin
a = A;
b = B;
if (a==0 || b==0) // q=0 when a or b equal 0
p = 15'b0;        
else if (a==1) // q=b when a equal 1
p = {8'b0000_0000,b};
else if (b==1) // q=a when b equal 1
p = {8'b0000_0000,a};
else 
begin
p = 15'b0;
for (i=0; i<8; i=i+1)
if  (b[i] == 1)
begin
                     temp = a << i; // shift left N bits
                     p = p + temp; 
end
end
    end
assign P = p;


endmodule