Add Numba void* -> typed-pointer intrinsics and tests #804
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create_voidptr_to_dtype_ptr_caster to bitcast void* to typed pointer. Provide convenience casters for common primitives: float64, float32, int32, int64. Add unit tests in test_numba_custom_data.py exercising the new casters: Tests cover basic float/double and int pointer casting and multi-parameter usage.
jhale
reviewed
Dec 5, 2025
jhale
reviewed
Dec 5, 2025
| b = numba.carray(b_, (1,), dtype=np.float64) | ||
| fptr = voidptr_to_float64_ptr(custom_data) | ||
| iptr = voidptr_to_int32_ptr(custom_data) | ||
| scale = fptr[0] |
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Bit hairy, in the future we should look and see if we can reinterpret the struct with its fields and let numba/llvm handle the offsets for us.
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I made some attempts but have not been able to find a nice and robust way yet. I tried with record caster.
…FCx utils ffcx: annotate create_voidptr_to_dtype_ptr_caster with type hints and clarify when void* casts are required. - Add docstring explaining use cases for voidptr cast (custom_data in UFCx kernels). - Validate input types early and raise clear TypingError on invalid source types.
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This PR adds a small, reliable Numba intrinsic factory for casting void* (FFCx custom_data) to typed C pointers and provides convenience casters for common primitive types, plus unit tests exercising those casters. This PR is relevant for custom_data functionality in dolfinx https://github.com/FEniCS/dolfinx/pull/4013.