3.3 ADD SHIFT MULTIPLIER

Shift-and-add multiplication is similar to the multiplication performed by paper and pencil. This method adds the multiplicand X to itself Y times, where Y denotes the multiplier. To multiply two numbers by paper and pencil, the algorithm is to take the digits of the multiplier one at a time from right to left, multiplying the multiplicand by a single digit of the multiplier and placing the intermediate product in the appropriate positions to the left of the earlier results.

DIAGRAM:

PROGRAM:

 

module addshift(a,b,result);

input [7:0] a;

input [7:0] b;

output [15:0] result;

wire [15:0] a1,a2,a3,a4,a5,a6,a7,a8;

assign a1=(b[0]==1'b1) ? {8'b00000000 , a } : 16'b0000000000000000;

assign a2=(b[1]==1'b1) ? {7'b0000000 , a , 1'b0} : 16'b0000000000000000;

assign a3=(b[2]==1'b1) ? {6'b000000 , a , 2'b00} : 16'b0000000000000000;

assign a4=(b[3]==1'b1) ? {5'b00000 , a , 3'b000} : 16'b0000000000000000;

assign a5=(b[4]==1'b1) ? {4'b0000 , a , 4'b0000} : 16'b0000000000000000;

assign a6=(b[5]==1'b1) ? {3'b000 , a , 5'b00000} : 16'b0000000000000000;

assign a7=(b[6]==1'b1) ? {2'b00 , a , 6'b000000} : 16'b0000000000000000;

assign a8=(b[7]==1'b1) ? {1'b0 , a , 7'b0000000} : 16'b0000000000000000;

assign result = a1+a2+a3+a4+a5+a6+a7+a8;

endmodule