This API is a submodule of the jpegXL encoder. It is an optimized implementation of the Xilinx HLS design methodology. This API is able to construct tokens of the orders of the ac coefficients of jpegXL. The supported AC strategy includes 8x8, IDENTITY, 16x16 and 32x32 DCT. The input of this API is a set of orders of coefficients to be encoded under all the supported strategies. And the output is a number of tokens which can be encoded by the following ANS encoder.