module booth_wallace_8x8 ( input clk, rst, input [7:0] a, b, output reg [15:0] prod ); // Radix-4 booth encoding, 4:2 compressor tree, // final CPA with pipelining at exact right stages. // Exactly 200 MHz on Artix-7.
// Instantiate the multiplier eight_bit_multiplier uut ( .a(a), .b(b), .product(product) );
assign cout = carry[WIDTH];
With so many implementations available, how do you decide which one to use? The answer depends on your design constraints:
Consider multiplying two binary numbers $A[7:0]$ and $B[7:0]$. 8bit multiplier verilog code github
assign sum = a ^ b ^ cin; assign cout = (a & b) | (b & cin) | (a & cin);
-bit numbers, the maximum possible size of the resulting product is bits. Therefore, our output requires a 16-bit register. module booth_wallace_8x8 ( input clk, rst, input [7:0]
There are three primary ways to implement this in hardware:
A great hands-on resource is the Booths_Multiplier_8bit repository by SarthakChor . This project provides a clean, behavioral Verilog implementation of an 8-bit Booth's multiplier. It iterates through eight cycles, checking the least significant bits of the accumulator to decide whether to add, subtract, or shift, and then performs arithmetic right shifts. The Booths_Multiplier_8bit.v module implements the core algorithm, and it also includes a Clk_divider.v module, which is a thoughtful addition for physical FPGA implementation where the clock speed might be too high to visually observe the iterative process. The answer depends on your design constraints: Consider
| | Choose… | | --- | --- | | Maximum speed and have plenty of logic resources | Wallace tree or Radix‑4 Booth + CLA (combinational) | | Minimal resource usage and low speed is acceptable | Sequential shift‑and‑add multiplier | | Balanced area‑speed trade‑off | Vedic multiplier or multi‑cycle Radix‑4 Booth | | Signed multiplication only | Booth’s algorithm or a dedicated signed two’s complement multiplier | | Ultra‑low power and error tolerance | Approximate multiplier | | An FPGA‑specific implementation | theashix’s SystemVerilog multiplier (Spartan‑7) or OmarMongy’s sequential design (with 7‑segment display) | | To learn from a well‑commented, modular design | Vedic multiplier by kk‑abhishek or the parameterised Booth multiplier by MorrisMA |