System configuration

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.

NPY_SIZEOF_SHORT

sizeof(short)

NPY_SIZEOF_INT

sizeof(int)

NPY_SIZEOF_LONG

sizeof(long)

NPY_SIZEOF_LONGLONG

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

NPY_SIZEOF_PY_LONG_LONG

NPY_SIZEOF_FLOAT

sizeof(float)

NPY_SIZEOF_DOUBLE

sizeof(double)

NPY_SIZEOF_LONG_DOUBLE

NPY_SIZEOF_LONGDOUBLE

sizeof(longdouble)

NPY_SIZEOF_PY_INTPTR_T

Size of a pointer void * and intptr_t/Py_intptr_t.

NPY_SIZEOF_INTP

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

Platform information

NPY_CPU_X86

NPY_CPU_AMD64

NPY_CPU_IA64

NPY_CPU_PPC

NPY_CPU_PPC64

NPY_CPU_SPARC

NPY_CPU_SPARC64

NPY_CPU_S390

NPY_CPU_PARISC

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

Defined in numpy/npy_cpu.h

NPY_LITTLE_ENDIAN

NPY_BIG_ENDIAN

NPY_BYTE_ORDER

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

Defined in numpy/npy_endian.h.

int PyArray_GetEndianness()

Returns the endianness of the current platform. One of NPY_CPU_BIG, NPY_CPU_LITTLE, or NPY_CPU_UNKNOWN_ENDIAN.

NPY_CPU_BIG

NPY_CPU_LITTLE

NPY_CPU_UNKNOWN_ENDIAN

Compiler directives

NPY_LIKELY

NPY_UNLIKELY

NPY_UNUSED