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# Extending via CFFI

    """
    Use cffi to access any of the underlying C functions from distributions.h
    """
    import os

    import cffi

    import numpy as np

    from .parse import parse_distributions_h

    ffi = cffi.FFI()

    inc_dir = os.path.join(np.get_include(), 'numpy')

    # Basic numpy types
    ffi.cdef('''
        typedef intptr_t npy_intp;
        typedef unsigned char npy_bool;

    ''')

    parse_distributions_h(ffi, inc_dir)

    lib = ffi.dlopen(np.random._generator.__file__)

    # Compare the distributions.h random_standard_normal_fill to
    # Generator.standard_random
    bit_gen = np.random.PCG64()
    rng = np.random.Generator(bit_gen)
    state = bit_gen.state

    interface = rng.bit_generator.cffi
    n = 100
    vals_cffi = ffi.new(f'double[{n}]')
    lib.random_standard_normal_fill(interface.bit_generator, n, vals_cffi)

    # reset the state
    bit_gen.state = state

    vals = rng.standard_normal(n)

    for i in range(n):
        assert vals[i] == vals_cffi[i]