cannam@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@0: 
cannam@0: /*
cannam@0:     QM DSP library
cannam@0:     Centre for Digital Music, Queen Mary, University of London.
cannam@0:     This file Copyright 2006 Chris Cannam.
cannam@0:     All rights reserved.
cannam@0: */
cannam@0: 
cannam@0: #ifndef _WINDOW_H_
cannam@0: #define _WINDOW_H_
cannam@0: 
cannam@0: #include <cmath>
cannam@0: #include <iostream>
cannam@0: #include <map>
cannam@0: 
cannam@0: enum WindowType {
cannam@0:     RectangularWindow,
cannam@0:     BartlettWindow,
cannam@0:     HammingWindow,
cannam@0:     HanningWindow,
cannam@0:     BlackmanWindow,
cannam@0:     GaussianWindow,
cannam@0:     ParzenWindow
cannam@0: };
cannam@0: 
cannam@0: template <typename T>
cannam@0: class Window
cannam@0: {
cannam@0: public:
cannam@0:     /**
cannam@0:      * Construct a windower of the given type.
cannam@0:      */
cannam@0:     Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); }
cannam@0:     Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
cannam@0:     Window &operator=(const Window &w) {
cannam@0: 	if (&w == this) return *this;
cannam@0: 	m_type = w.m_type;
cannam@0: 	m_size = w.m_size;
cannam@0: 	encache();
cannam@0: 	return *this;
cannam@0:     }
cannam@26:     virtual ~Window() { delete[] m_cache; }
cannam@0:     
cannam@0:     void cut(T *src) const { cut(src, src); }
cannam@55:     void cut(const T *src, T *dst) const {
cannam@0: 	for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
cannam@0:     }
cannam@0: 
cannam@0:     WindowType getType() const { return m_type; }
cannam@0:     size_t getSize() const { return m_size; }
cannam@0: 
cannam@0: protected:
cannam@0:     WindowType m_type;
cannam@0:     size_t m_size;
cannam@0:     T *m_cache;
cannam@0:     
cannam@0:     void encache();
cannam@0: };
cannam@0: 
cannam@0: template <typename T>
cannam@0: void Window<T>::encache()
cannam@0: {
cannam@0:     size_t n = m_size;
cannam@0:     T *mult = new T[n];
cannam@0:     size_t i;
cannam@0:     for (i = 0; i < n; ++i) mult[i] = 1.0;
cannam@0: 
cannam@0:     switch (m_type) {
cannam@0: 		
cannam@0:     case RectangularWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * 0.5;
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case BartlettWindow:
cannam@0: 	for (i = 0; i < n/2; ++i) {
cannam@0: 	    mult[i] = mult[i] * (i / T(n/2));
cannam@0: 	    mult[i + n/2] = mult[i + n/2] * (1.0 - (i / T(n/2)));
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case HammingWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n));
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case HanningWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n));
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case BlackmanWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n)
cannam@0: 				 + 0.08 * cos(4 * M_PI * i / n));
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case GaussianWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * exp((-1.0 / (n*n)) * ((T(2*i) - n) *
cannam@0: 						      (T(2*i) - n)));
cannam@0: 	}
cannam@0: 	break;
cannam@0: 	    
cannam@0:     case ParzenWindow:
cannam@0: 	for (i = 0; i < n; ++i) {
cannam@0: 	    mult[i] = mult[i] * (1.0 - fabs((T(2*i) - n) / T(n + 1)));
cannam@0: 	}
cannam@0: 	break;
cannam@0:     }
cannam@0: 	
cannam@0:     m_cache = mult;
cannam@0: }
cannam@0: 
cannam@0: #endif