CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is a MicroPython native module implementing the FNV-1a 32-bit hash function. It provides a high-performance C implementation that runs ~1000x faster than pure Python on embedded devices like the RP2040.

Build Commands

Building requires MicroPython source and uses the native module build system:

# Set the MicroPython source directory
export MPY_DIR=../micropython

# Build for default architecture (x64)
make

# Build for specific architecture (e.g., armv6m for RP2040)
ARCH=armv6m make

# Clean build artifacts
make clean

Supported architectures: x64, x86, armv6m, armv7m, armv7emsp, armv7emdp, xtensa, xtensawin, rv32imc

Running Tests

Tests require Belay to run on MicroPython:

make clean && make
belay run micropython -m unittest tests/test_fnv1a32.py

Running Benchmarks

Benchmarks run on actual hardware (e.g., RP2040):

ARCH=armv6m make
belay install /dev/ttyUSB0 --with=dev
belay sync /dev/ttyUSB0 fnv1a32.mpy
belay run /dev/ttyUSB0 benchmark/fnv1a32_benchmark.py

Architecture

• src/fnv1a32.c - C implementation of the FNV-1a hash loop with 16-byte unrolling for performance. Handles both buffer objects and file-like objects via readinto.
• src/fnv1a32.py - Python wrapper exposing the fnv1a32() function that calls the C _fnv1a32() implementation.
• Makefile - Uses MicroPython's dynruntime.mk to build the .mpy native module.

The module exports a single function fnv1a32(obj, state=0x811C9DC5, *, buffer=4096) that accepts bytes/bytearray/str or file-like objects.