C extensions

The ordec package contains four C extensions, all defined in setup.py:

ordec.core.ordb._ordb: the ORDB core (see ORDB native core), sources in src/ordec/core/ordb/native/. It is required; there is no pure-Python fallback.
ordec.layout._gdsrecords: GDS record scanning, source src/ordec/layout/_gdsrecords.c. It is optional: if it cannot be built, ordec.layout.gdsrecords falls back to an equivalent, but much slower pure-Python implementation.
ordec.schematic._auto_wire and ordec.schematic._annotate: inner loops of the schematic router (A* search, blocked move updates) and of the annotation placement (empty region scan), sources in src/ordec/schematic/. They are required like the ORDB core.

Building

Building requires a C compiler and the Python headers (on Debian: sudo apt-get install build-essential python3-dev).

pip3 install -e .[test] builds the extensions into the source tree (src/ordec/core/ordb/_ordb.abi3.so, src/ordec/layout/_gdsrecords.abi3.so, src/ordec/schematic/_auto_wire.abi3.so, src/ordec/schematic/_annotate.abi3.so). After changing the C sources, or after pulling changes to them, run the same command again. For a quick rebuild during development, python3 setup.py build_ext --inplace does the same if setuptools is installed.

A missing or failed build of the ORDB core shows up on import as:

ImportError: cannot import name '_ordb' from partially initialized module 'ordec.core.ordb'

Limited API

All extensions use only the limited API of Python 3.11 (Py_LIMITED_API in the sources), so one abi3 build serves all Python versions from 3.11. The limited API has no static types, no access to type object fields and no macros like PyTuple_GET_ITEM: the types are heap types created with PyType_FromSpec, and the function forms of the macros cost 2 to 3% on the ORDB benchmarks. A version-specific build left in the source tree (_ordb.cpython-313-*.so) is imported in preference to the abi3 one; delete it after switching.