`timescale 1ns / 1ps
: The most basic hardware approach, which performs multiplication over multiple clock cycles. It is modular and resource-efficient for low-speed applications. A multi-cycle sequential version is hosted by OmarMongy on GitHub . Example: Simple 8-bit Behavioral Multiplier
clk : Pin E3 (100 MHz onboard clock) rst_n : Pin C2 (Button center) A[7:0] : Pin J15, J14, J13, J12, H15, H14, H13, H12 (Switches) B[7:0] : Pin K15, K14, K13, K12, L15, L14, L13, L12 (Switches) P[15:0]: Pin R11, R10, R9, R8, T11, T10, T9, T8, U11, U10, U9, U8, V11, V10, V9, V8 (LEDs) done : Pin R12 (LED)
$display("All Tests Passed!"); $finish; end
If you are interested in a specific optimization, please let me know: Do you need for higher clock speeds? Are you targeting FPGA (Xilinx/Intel) or ASIC ? 8bit multiplier verilog code github
// Calculate partial products generate for (i = 0; i < 8; i = i + 1) begin : gen_pp_rows for (j = 0; j < 8; j = j + 1) begin : gen_pp_cols // Partial product is A[j] AND B[i] // We place it in the correct "shifted" column position // Column index = i + j assign pp[i][i+j] = A[j] & B[i]; end end endgenerate
module multiplier_8bit( input [7:0] A, input [7:0] B, output [15:0] Product );
module tb_multiplier_8bit;
If you prefer to write your own Verilog code rather than using an existing repository, here are some best practices: `timescale 1ns / 1ps : The most basic
// File: multiplier_8bit_structural.v module multiplier_8bit_structural ( input wire [7:0] A, input wire [7:0] B, output wire [15:0] P ); wire [7:0] p_prod [7:0]; // Matrix to hold 64 partial products // Generate partial products genvar i, j; generate for (i = 0; i < 8; i = i + 1) begin : gen_p_prod_row for (j = 0; j < 8; j = j + 1) begin : gen_p_prod_col assign p_prod[i][j] = A[j] & B[i]; end end endgenerate // Internal wires for adder tree connections wire [7:0] sum [6:0]; wire [7:0] carry [6:0]; // Row 0 Initialization assign P[0] = p_prod[0][0]; // Manual/Loop assignment of the adder array for reduction // (For a highly optimized structural repository, explicitly instantiate // full_adder and half_adder modules here to demonstrate gate-level routing) // Simple dataflow equivalent of the structural addition chain: assign carry[0], sum[0] = p_prod[0][7:1] + p_prod[1][6:0]; assign P[1] = sum[0][0]; assign carry[1], sum[1] = carry[0], p_prod[1][7] + sum[0][7:1] + p_prod[2][6:0]; assign P[2] = sum[1][0]; assign carry[2], sum[2] = carry[1], p_prod[2][7] + sum[1][7:1] + p_prod[3][6:0]; assign P[3] = sum[2][0]; assign carry[3], sum[3] = carry[2], p_prod[3][7] + sum[2][7:1] + p_prod[4][6:0]; assign P[4] = sum[3][0]; assign carry[4], sum[4] = carry[3], p_prod[4][7] + sum[3][7:1] + p_prod[5][6:0]; assign P[5] = sum[4][0]; assign carry[5], sum[5] = carry[4], p_prod[5][7] + sum[4][7:1] + p_prod[6][6:0]; assign P[6] = sum[5][0]; assign carry[6], sum[6] = carry[5], p_prod[6][7] + sum[5][7:1] + p_prod[7][6:0]; assign P[7] = sum[6][0]; // Final upper bits computation assign P[15:8] = carry[6], p_prod[7][7] + sum[6][7:1]; endmodule Use code with caution. 3. Writing the Testbench (Simulation File)
# Compile and simulate iverilog -o multiplier_tb tb/testbench.v src/*.v vvp multiplier_tb
// --------------------------------------------------------- // Step 1: Generate Partial Products (The AND gate grid) // --------------------------------------------------------- genvar i, j;
endmodule
// Generate Partial Products genvar r, c; generate for (r = 0; r < 8; r=r+1) begin : ROW for (c = 0; c < 8; c=c+1) begin : COL assign pp[r][c] = A[c] & B[r]; end end endgenerate
This design is ideal for most FPGA projects because tools like AMD Vivado or Intel Quartus automatically map this code to dedicated, high-speed DSP blocks inside the chip.
A Wallace Tree multiplier optimizes the addition phase. It uses Full Adders as 3:2 compressors to reduce partial products in parallel layers. This changes the addition delay from linear to logarithmic , making it ideal for high-speed designs. 2. Synthesizable 8-Bit Verilog Implementations