Parity

Hamming Distance 8-Bit — L1 Upgrade

Glitch-free registered Hamming distance calculator for 8-bit vectors using $countones.

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About this block

Simulate it in the Verilog IDE

Easyverilogsimsyn

Hamming Distance 8-Bit — L1 Upgrade is a Verilog reference block in the Parity catalog. Even/odd parity generators, checkers, and error-detection helpers. Marked Easy: a small block you can read, simulate, and synthesize in one sitting.

This IP provides a robust, registered population count (Hamming weight) calculator for 8-bit vectors.

It is ideal for L1 upgrade scenarios requiring glitch-free synchronous outputs.

The design uses SystemVerilog's $countones system function for efficient population counting and ensures clean timing by registering the output.

Glitch-Free Output: Registered output prevents metastability and glitches in downstream logic.
Efficient Implementation: Uses SystemVerilog $countones for optimal synthesis.
Synchronous Interface: Standard valid handshake using valid_in and valid_out.

Choose Open in IDE. RTL Studio loads the packaged workspace for Hamming Distance 8-Bit — L1 Upgrade.
Read the Verilog module in the editor. The catalog line for this block: Glitch-free registered Hamming distance calculator for 8-bit vectors using $countones.
Run the packaged testbench with the in-browser Verilator simulator, then open the VCD in the waveform viewer.
Run Yosys in the same IDE for a generic netlist. Sky130 liberty mapping is a separate Pro library option.

RTL Studio is the Verilog simulator and IDE around this block: Slang lint, Verilator, VCD waveforms, and Yosys, in the browser. Simulation guide · Yosys guide.

Architecture

The design consists of a single synchronous stage. Input data is sampled on the rising clock edge when valid_in is asserted. The result is registered to ensure clean timing and glitch-free behavior.

Ports

Port Name	Direction	Width	Description
clk	Input	1	Clock input
rst_n	Input	1	Active-low reset
data_in	Input	8	Input data vector
valid_in	Input	1	Data valid strobe
pop_count	Output	4	Calculated population count
valid_out	Output	1	Output valid strobe

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