Activate FFT related OPs for C++

Hi, I’m new to the TensorFlow world and I’m trying to enable the spectral OP which includes FFT-related OP kernels for C++. I found both FFT OPkernels and OPs are registered but they are not available for C++ APIs. I spent several days trying to figure out the dependency of the BUILD files but it did not go very well.
What should I do if I want to use these registered OPs and construct the header files for C++? Does anyone have some experience with this? Please give me some ideas or hints. Thanks a lot.

I suppose it could be accessed as SIG jvm is exposing it.

You are interested to look at how an alternative FFT is plugged take a look at:

Thanks for replying. It is a good start for me.

Meanwhile, I’m still thinking if I can do the C++ building by adjusting the Bazel BUILD files to activate the FFT OPs since they are available in Python tf.signal. I tried to mimic source code from to user_ops for duplicating the FFT functions but I have trouble with including the third party Eigen headers and dependencies. I also tried to use some name tricks by switching these registered OP names to see if I can make a short cut but none of them work. For now, the only way I can imagine is to go through these BUILD and workplace files in detail to see if I can find the correct path for building but it may take a long time for me.
I hope if there is someone did this before and can point me the correct way. Thanks.