/* 
 * Fast Fourier transform
 * 
 * Copyright (c) 2021 Project Nayuki. (MIT License)
 * https://www.nayuki.io/page/fast-fourier-transform-in-x86-assembly
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 * - The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 * - The Software is provided "as is", without warranty of any kind, express or
 *   implied, including but not limited to the warranties of merchantability,
 *   fitness for a particular purpose and noninfringement. In no event shall the
 *   authors or copyright holders be liable for any claim, damages or other
 *   liability, whether in an action of contract, tort or otherwise, arising from,
 *   out of or in connection with the Software or the use or other dealings in the
 *   Software.
 */

#pragma once

#include <complex>
#include <cstddef>
#include <vector>


class Fft final {
	
	/*---- Fields ----*/
	
	private: int levels;
	
	private: std::vector<std::size_t> bitReversal;
	
	private: std::complex<double> *expTable;
	
	
	/*---- Constructor/destructor ----*/
	
	public: explicit Fft(std::size_t n);
	
	public: ~Fft();
	
	
	/*---- Method ----*/
	
	public: void transform(std::complex<double> *vec) const;
	
	
	/*---- Functions ----*/
	
	private: static std::size_t reverseBits(std::size_t val, int width);
	
	private: static int log2Exact(std::size_t val);
	
};