Where is the real implementation of cv_hal_dft2D?

Dear all,

I am reading OpenCV 4 source code related to template matching. I found internally it will call cv_hal_dft2D. But it points to a fake implementation in modules/core/src/hal_replacement.hpp.

inline int hal_ni_dft2D(cvhalDFT *context, const uchar *src_data, size_t src_step, uchar *dst_data, size_t dst_step) { return CV_HAL_ERROR_NOT_IMPLEMENTED; }
#define cv_hal_dft2D hal_ni_dft2D

Could anyone help to find where the real implementation is? Or for now, there has no HAL version for dft2D?

Thanks a lot!