Jungfraujoch/image_analysis/indexing/FFTIndexerCPU.h

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only


#pragma once

#include <vector>
#include <fftw3.h>

#include "FFTIndexer.h"

#include "../../common/Coord.h"

// CPU/FFTW-based FFT indexer (drop-in replacement for the CUDA version).
class FFTIndexerCPU : public FFTIndexer {
    // Host-side buffers for batched FFTW
    // Input: [nDirections][histogram_size]
    // Output (R2C): [nDirections][(histogram_size/2)+1]
    std::vector<float> h_input_fft;
    std::vector<std::array<float,2>> h_output_fft; // fftw_complex-compatible layout

    fftwf_plan plan;

    void ExecuteFFT(const std::vector<Coord> &coord, size_t nspots) override;

public:
    explicit FFTIndexerCPU(const IndexingSettings& settings);
    FFTIndexerCPU(const FFTIndexerCPU&) = delete;
    FFTIndexerCPU& operator=(const FFTIndexerCPU&) = delete;
    ~FFTIndexerCPU() override;
};