* Initial import

src/Window.h

@@ -0,0 +1,161 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Rubber Band
+    An audio time-stretching and pitch-shifting library.
+    Copyright 2007 Chris Cannam.
+    
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef _RUBBERBAND_WINDOW_H_
+#define _RUBBERBAND_WINDOW_H_
+
+#include <cmath>
+#include <iostream>
+#include <map>
+
+enum WindowType {
+    RectangularWindow,
+    BartlettWindow,
+    HammingWindow,
+    HanningWindow,
+    BlackmanWindow,
+    GaussianWindow,
+    ParzenWindow,
+    NuttallWindow,
+    BlackmanHarrisWindow
+};
+
+template <typename T>
+class Window
+{
+public:
+    /**
+     * Construct a windower of the given type.
+     */
+    Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); }
+    Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
+    Window &operator=(const Window &w) {
+	if (&w == this) return *this;
+	m_type = w.m_type;
+	m_size = w.m_size;
+	encache();
+	return *this;
+    }
+    virtual ~Window() { delete[] m_cache; }
+    
+    void cut(T *src) const { cut(src, src); }
+    void cut(T *src, T *dst) const {
+	for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
+    }
+
+    T getArea() { return m_area; }
+    T getValue(size_t i) { return m_cache[i]; }
+
+    WindowType getType() const { return m_type; }
+    size_t getSize() const { return m_size; }
+
+protected:
+    WindowType m_type;
+    size_t m_size;
+    T *m_cache;
+    T m_area;
+    
+    void encache();
+    void cosinewin(T *, T, T, T, T);
+};
+
+template <typename T>
+void Window<T>::encache()
+{
+    int n = int(m_size);
+    T *mult = new T[n];
+    int i;
+    for (i = 0; i < n; ++i) mult[i] = 1.0;
+
+    switch (m_type) {
+		
+    case RectangularWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] *= 0.5;
+	}
+	break;
+	    
+    case BartlettWindow:
+	for (i = 0; i < n/2; ++i) {
+	    mult[i] *= (i / T(n/2));
+	    mult[i + n/2] *= (1.0 - (i / T(n/2)));
+	}
+	break;
+	    
+    case HammingWindow:
+        cosinewin(mult, 0.54, 0.46, 0.0, 0.0);
+	break;
+	    
+    case HanningWindow:
+        cosinewin(mult, 0.50, 0.50, 0.0, 0.0);
+	break;
+	    
+    case BlackmanWindow:
+        cosinewin(mult, 0.42, 0.50, 0.08, 0.0);
+	break;
+	    
+    case GaussianWindow:
+	for (i = 0; i < n; ++i) {
+            mult[i] *= pow(2, - pow((i - (n-1)/2.0) / ((n-1)/2.0 / 3), 2));
+	}
+	break;
+	    
+    case ParzenWindow:
+    {
+        int N = n-1;
+        for (i = 0; i < N/4; ++i) {
+            T m = 2 * pow(1.0 - (T(N)/2 - i) / (T(N)/2), 3);
+            mult[i] *= m;
+            mult[N-i] *= m;
+        }
+        for (i = N/4; i <= N/2; ++i) {
+            int wn = i - N/2;
+            T m = 1.0 - 6 * pow(wn / (T(N)/2), 2) * (1.0 - abs(wn) / (T(N)/2));
+            mult[i] *= m;
+            mult[N-i] *= m;
+        }            
+        break;
+    }
+
+    case NuttallWindow:
+        cosinewin(mult, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
+	break;
+
+    case BlackmanHarrisWindow:
+        cosinewin(mult, 0.35875, 0.48829, 0.14128, 0.01168);
+        break;
+    }
+	
+    m_cache = mult;
+
+    m_area = 0;
+    for (int i = 0; i < n; ++i) {
+        m_area += m_cache[i];
+    }
+    m_area /= n;
+}
+
+template <typename T>
+void Window<T>::cosinewin(T *mult, T a0, T a1, T a2, T a3)
+{
+    int n = int(m_size);
+    for (int i = 0; i < n; ++i) {
+        mult[i] *= (a0
+                    - a1 * cos(2 * M_PI * i / n)
+                    + a2 * cos(4 * M_PI * i / n)
+                    - a3 * cos(6 * M_PI * i / n));
+    }
+}
+
+#endif