From 26293db40f8ac62f3971e0e9dbbc0bf3439e61c0 Mon Sep 17 00:00:00 2001
From: Vasile Vilvoiu <vasi.vilvoiu@gmail.com>
Date: Tue, 29 Dec 2020 19:33:03 +0200
Subject: Initial commit

---
 src/fft.hpp | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 src/fft.hpp

(limited to 'src/fft.hpp')

diff --git a/src/fft.hpp b/src/fft.hpp
new file mode 100644
index 0000000..9eac372
--- /dev/null
+++ b/src/fft.hpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2020-2021 Vasile Vilvoiu <vasi.vilvoiu@gmail.com>
+ *
+ * specgram is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef _FFT_HPP_
+#define _FFT_HPP_
+
+#include "window-function.hpp"
+
+#include <fftw3.h>
+
+class FFT {
+private:
+    /* FFT window width */
+    const std::size_t window_width_;
+
+    /* fftw buffers */
+    fftw_complex *in_;
+    fftw_complex *out_;
+
+    /* fftw plan */
+    fftw_plan plan_;
+
+    /* window function */
+    std::unique_ptr<WindowFunction> window_function_;
+
+public:
+    FFT() = delete;
+    FFT(const FFT &c) = delete;
+    FFT(FFT &&) = delete;
+    FFT & operator=(const FFT&) = delete;
+
+    FFT(std::size_t win_width, std::unique_ptr<WindowFunction>& win_func);
+    virtual ~FFT();
+
+    ComplexWindow Compute(const ComplexWindow& input);
+
+    static RealWindow GetMagnitude(const ComplexWindow& input, bool alias);
+    static std::tuple<double, double> GetFrequencyLimits(double rate, std::size_t width);
+    static double GetFrequencyIndex(double rate, std::size_t width, double f);
+    static RealWindow Resample(const RealWindow& input, double rate, std::size_t width, double fmin, double fmax);
+    static RealWindow Crop(const RealWindow& input, double rate, double fmin, double fmax);
+};
+
+#endif
\ No newline at end of file
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