Function npyiter_undo_iter_axis_perm

numpy/core/src/multiarray/nditer_impl.h:335–352

* Undo the axis permutation of the iterator. When the operand has fewer * dimensions then the iterator, this can return negative values for * inserted (broadcast) dimensions. * * @param axis Axis for which to undo the iterator axis permutation. * @param ndim If `op_axes` is being used, this is the iterator dimension, * otherwise this is the operand dimension. * @param perm The i

 *         `op_axes` this indexes into `op_axes` (unpermuted iterator axis)
 */
static inline int
npyiter_undo_iter_axis_perm(
        int axis, int ndim, const npy_int8 *perm, npy_bool *axis_flipped)
{
    npy_int8 p = perm[axis];
    /* The iterator treats axis reversed, thus adjust by ndim */
    npy_bool flipped = p < 0;
    if (axis_flipped != NULL) {
        *axis_flipped = flipped;
    }
    if (flipped) {
        axis = ndim + p;
    }
    else {
        axis = ndim - p - 1;
    }
    return axis;
}

NPY_NO_EXPORT void
npyiter_coalesce_axes(NpyIter *iter);