System configuration

.. sectionauthor:: Travis E. Oliphant

When NumPy is built, information about system configuration is recorded, and is made available for extension modules using NumPy's C API. These are mostly defined in numpyconfig.h (included in ndarrayobject.h). The public symbols are prefixed by NPY_*. NumPy also offers some functions for querying information about the platform in use.

For private use, NumPy also constructs a config.h in the NumPy include directory, which is not exported by NumPy (that is a python extension which use the numpy C API will not see those symbols), to avoid namespace pollution.

Data type sizes

The NPY_SIZEOF_{CTYPE} constants are defined so that sizeof information is available to the pre-processor.

.. c:macro:: NPY_SIZEOF_SHORT

sizeof(short)

.. c:macro:: NPY_SIZEOF_INT

sizeof(int)

.. c:macro:: NPY_SIZEOF_LONG

sizeof(long)

.. c:macro:: NPY_SIZEOF_LONGLONG

sizeof(longlong) where longlong is defined appropriately on the
platform.

.. c:macro:: NPY_SIZEOF_PY_LONG_LONG

.. c:macro:: NPY_SIZEOF_FLOAT

sizeof(float)

.. c:macro:: NPY_SIZEOF_DOUBLE

sizeof(double)

.. c:macro:: NPY_SIZEOF_LONG_DOUBLE

.. c:macro:: NPY_SIZEOF_LONGDOUBLE

sizeof(longdouble)

.. c:macro:: NPY_SIZEOF_PY_INTPTR_T

Size of a pointer ``void *`` and ``intptr_t``/``Py_intptr_t``.

.. c:macro:: NPY_SIZEOF_INTP

Size of a ``size_t`` on this platform (``sizeof(size_t)``)

Platform information

.. c:macro:: NPY_CPU_X86 .. c:macro:: NPY_CPU_AMD64 .. c:macro:: NPY_CPU_IA64 .. c:macro:: NPY_CPU_PPC .. c:macro:: NPY_CPU_PPC64 .. c:macro:: NPY_CPU_SPARC .. c:macro:: NPY_CPU_SPARC64 .. c:macro:: NPY_CPU_S390 .. c:macro:: NPY_CPU_PARISC

CPU architecture of the platform; only one of the above is
defined.

Defined in ``numpy/npy_cpu.h``

.. c:macro:: NPY_LITTLE_ENDIAN

.. c:macro:: NPY_BIG_ENDIAN

.. c:macro:: NPY_BYTE_ORDER

Portable alternatives to the ``endian.h`` macros of GNU Libc.
If big endian, :c:data:`NPY_BYTE_ORDER` == :c:data:`NPY_BIG_ENDIAN`, and
similarly for little endian architectures.

Defined in ``numpy/npy_endian.h``.

.. c:function:: int PyArray_GetEndianness()

Returns the endianness of the current platform.
One of :c:data:`NPY_CPU_BIG`, :c:data:`NPY_CPU_LITTLE`,
or :c:data:`NPY_CPU_UNKNOWN_ENDIAN`.

.. c:macro:: NPY_CPU_BIG

.. c:macro:: NPY_CPU_LITTLE

.. c:macro:: NPY_CPU_UNKNOWN_ENDIAN

Compiler directives

.. c:macro:: NPY_LIKELY .. c:macro:: NPY_UNLIKELY .. c:macro:: NPY_UNUSED