cyphal-reassemble 0.1.0

Fast Cyphal/CAN transfer reassembly (Python wrapper over libcanard binary)

cyphal-reassemble

Standalone reassembler of Cyphal/CAN v1.0 transfers, built on libcanard. Reads an Arrow IPC stream of pre-filtered Cyphal frames from stdin and writes an Arrow IPC stream of reassembled transfers to stdout.

Designed as a fast, compiled replacement for the pycyphal-based reassembly step of the frame-decoding pipeline. It is deliberately channel/logger/session agnostic: all such semantics stay in the calling pipeline.

Build

sudo dnf install -y libarrow-devel cmake gcc-c++ git make   # Fedora
git clone --recurse-submodules <repo-url>
cd cyphal-reassemble
make

make configures and builds into build/ (Release by default). Other targets:

make clean                 # remove build/
make help                  # list targets and variables
make BUILD_TYPE=Debug      # debug build

Usage

build/cyphal-reassemble < frames.arrows > transfers.arrows
build/cyphal-reassemble --help

Input schema (Arrow IPC stream)

Column	Type	Required
timestamp	timestamp[us, UTC]	yes
id	uint32 (29-bit CAN ID)	yes
data	binary (incl. tail)	yes
rti	uint8	no (default 0)

Extra columns are ignored. One invocation handles one reassembly domain (typically one CAN channel).

Output schema (Arrow IPC stream)

Column	Type	Required
timestamp	timestamp[us, UTC]	yes
type	utf8 (Message|Request|Response)	yes
id	int16 (subject-id or service-id)	yes
source	uint8 (null if anonymous)	no
dest	uint8 (null for messages)	no
priority	uint8	no
transfer_id	uint8	no
payload	binary (raw reassembled bytes)	no
length	int32 (payload byte count)	no

Matches sc_schema.TransferSchema minus channel, which the pipeline re-attaches.

Diagnostics and a summary line (frames_in / transfers_out / errors / oom) go to stderr. Exit code is non-zero only on fatal I/O or schema errors.

Test

make test

Other test targets:

make test-unit             # unit tests only
make test-golden           # golden parity tests (tests/data/)

Golden fixtures under tests/data/ are vendored from the frame-decoding pipeline.

License

MIT

Python package

Requires uv. Build the C++ binary first (see Build above), then:

uv sync

Usage:

import pyarrow.ipc as ipc
from cyphal_reassemble import reassemble

with open("tests/data/frames_CAN1.arrows", "rb") as f:
    frames = ipc.open_stream(f).read_all()

transfers = reassemble(frames)

Environment:

• CYPHAL_REASSEMBLE_BIN — override path to the executable (optional)

Install from PyPI (Linux x86_64)

pip install cyphal-reassemble
# or: uv add cyphal-reassemble

Requires Linux x86_64 with glibc ≥ manylinux_2_28. The wheel bundles the cyphal-reassemble binary and libarrow; no local C++ build needed.

Other platforms: clone this repo, run make, then uv sync (editable install).

Run Python tests:

uv run pytest python_tests/ -v

Lint:

uv run ruff check .