Question

write the code for 16-bit ALU using vivado.

Approach : A hierarchical design approach for 16-bit ALU using a Full Adders (16-bit), Multiplier (16-bit), Full Subtractor (16-bit), and shift left A register. include test bench.

S0 S1 Alu-operation

0 0 addition

0 1 subtraction

1 0 multiplication

1 1 shift right

Answer 1

//Top file

module alu(

input [15:0] A, B,

input S1, S0,

input cin, //cin for adder or borrow in for subtractor

output reg cout, //cout for adder or borrow out for subtractor

output reg [15:0] alu_out   

);

wire [15:0] add16, sub16, shift;

reg [15:0] result;

wire carry, borrow;

wire [31:0] mult;

adder16 uut0 (A, B, cin, add16, carry);

subtractor16 uut1 (A, B, cin, sub16, borrow);

multiplier16 uut2 (A, B, mult);

shiftA uut3 (A, shift);

always @ (S1, S0, add16, sub16, mult, shift)

begin

case ({S1, S0})

2'b00: begin alu_out <= add16; cout <= carry; end

2'b01: begin alu_out <= sub16; cout <= borrow; end

2'b10: alu_out <= mult[15:0];

2'b11: alu_out <= shift;

default : alu_out <= 4'h0000;

endcase

end

endmodule

//adder 16 bit

module adder16 (A, B, cin, SUM, Cout);

input [15:0] A, B;
input cin;
output [15:0] SUM;
output Cout;

assign {Cout, SUM} = cin + A + B;

endmodule

//

module subtractor16 (A, B, bin, difference, bout);

input [15:0] A, B;
input bin;
output [15:0] difference;
output bout;

assign {bout, difference} = A - B - bin;

endmodule

//multiplier

module multiplier16 (A, B, PRODUCT);

input [15:0] A, B;

output [31:0] PRODUCT;

assign PRODUCT = A * B;

endmodule

//Shift

module shiftA (A, RESULT);

input [15:0] A;

output [15:0] RESULT;

assign RESULT = A >> 1;

endmodule

//testbench

module tb_alu;

// Inputs

reg [15:0] A;

reg [15:0] B;

reg S1;

reg S0;

reg cin;

// Outputs

wire cout;

wire [15:0] alu_out;

// Instantiate the Unit Under Test (UUT)

alu uut (

.A(A),

.B(B),

.S1(S1),

.S0(S0),

.cin(cin),

.cout(cout),

.alu_out(alu_out)

);

initial begin

// Initialize Inputs

A = 0;

B = 0;

S1 = 0;

S0 = 0;

cin = 0;

// Wait 100 ns for global reset to finish

#100;

  

// Add stimulus here

A = 16'b0000000000001000; //8

B = 16'b0000000000000100; //4

S1 = 1'b0;

S0 = 1'b0;

#20;

S1 = 1'b0;

S0 = 1'b1;

#20;

S1 = 1'b1;

S0 = 1'b0;

#20;

S1 = 1'b1;

S0 = 1'b1;

#50 $finish;

end

  

endmodule

//Simulation