Function PyArray_CopyAsFlat

numpy/core/src/multiarray/ctors.c:2565–2747

* Private implementation of PyArray_CopyAnyInto with an additional order * parameter. */

 * parameter.
 */
NPY_NO_EXPORT int
PyArray_CopyAsFlat(PyArrayObject *dst, PyArrayObject *src, NPY_ORDER order)
{
    NpyIter *dst_iter, *src_iter;

    NpyIter_IterNextFunc *dst_iternext, *src_iternext;
    char **dst_dataptr, **src_dataptr;
    npy_intp dst_stride, src_stride;
    npy_intp *dst_countptr, *src_countptr;
    npy_uint32 baseflags;

    npy_intp dst_count, src_count, count;
    npy_intp dst_size, src_size;
    int needs_api;

    NPY_BEGIN_THREADS_DEF;

    if (PyArray_FailUnlessWriteable(dst, "destination array") < 0) {
        return -1;
    }

    /*
     * If the shapes match and a particular order is forced
     * for both, use the more efficient CopyInto
     */
    if (order != NPY_ANYORDER && order != NPY_KEEPORDER &&
            PyArray_NDIM(dst) == PyArray_NDIM(src) &&
            PyArray_CompareLists(PyArray_DIMS(dst), PyArray_DIMS(src),
                                PyArray_NDIM(dst))) {
        return PyArray_CopyInto(dst, src);
    }

    dst_size = PyArray_SIZE(dst);
    src_size = PyArray_SIZE(src);
    if (dst_size != src_size) {
        PyErr_Format(PyExc_ValueError,
                "cannot copy from array of size %" NPY_INTP_FMT " into an array "
                "of size %" NPY_INTP_FMT, src_size, dst_size);
        return -1;
    }

    /* Zero-sized arrays require nothing be done */
    if (dst_size == 0) {
        return 0;
    }

    baseflags = NPY_ITER_EXTERNAL_LOOP |
                NPY_ITER_DONT_NEGATE_STRIDES |
                NPY_ITER_REFS_OK;

    /*
     * This copy is based on matching C-order traversals of src and dst.
     * By using two iterators, we can find maximal sub-chunks that
     * can be processed at once.
     */
    dst_iter = NpyIter_New(dst, NPY_ITER_WRITEONLY | baseflags,
                                order,
                                NPY_NO_CASTING,