Function unpack_bits

numpy/core/src/multiarray/compiled_base.c:1753–1973

}

static PyObject *
unpack_bits(PyObject *input, int axis, PyObject *count_obj, char order)
{
    static int unpack_init = 0;
    /*
     * lookuptable for bitorder big as it has been around longer
     * bitorder little is handled via byteswapping in the loop
     */
    static union {
        npy_uint8  bytes[8];
        npy_uint64 uint64;
    } unpack_lookup_big[256];
    PyArrayObject *inp;
    PyArrayObject *new = NULL;
    PyArrayObject *out = NULL;
    npy_intp outdims[NPY_MAXDIMS];
    int i;
    PyArrayIterObject *it, *ot;
    npy_intp count, in_n, in_tail, out_pad, in_stride, out_stride;
    NPY_BEGIN_THREADS_DEF;

    inp = (PyArrayObject *)PyArray_FROM_O(input);

    if (inp == NULL) {
        return NULL;
    }
    if (PyArray_TYPE(inp) != NPY_UBYTE) {
        PyErr_SetString(PyExc_TypeError,
                "Expected an input array of unsigned byte data type");
        Py_DECREF(inp);
        goto fail;
    }

    new = (PyArrayObject *)PyArray_CheckAxis(inp, &axis, 0);
    Py_DECREF(inp);
    if (new == NULL) {
        return NULL;
    }

    if (PyArray_NDIM(new) == 0) {
        /* Handle 0-d array by converting it to a 1-d array */
        PyArrayObject *temp;
        PyArray_Dims newdim = {NULL, 1};
        npy_intp shape = 1;

        newdim.ptr = &shape;
        temp = (PyArrayObject *)PyArray_Newshape(new, &newdim, NPY_CORDER);
        Py_DECREF(new);
        if (temp == NULL) {
            return NULL;
        }
        new = temp;
    }

    /* Setup output shape */
    for (i = 0; i < PyArray_NDIM(new); i++) {
        outdims[i] = PyArray_DIM(new, i);
    }