FEAPIExamplePluginZeroCrossings/zplFFT_If.cpp

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//     /*! \file zplFFT_If.cpp: \brief interface of the CzplFFT_If class. */
//
//        Copyright (c) 2004-2007  
//        zplane.development
//        Flohrer Lerch Schwerdtfeger GbR
//        All rights reserved.
//
//        Redistribution and use in source and binary forms, with or without 
//        modification, are permitted provided that the following conditions 
//        are met:
//
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//            notice, this list of conditions and the following disclaimer. 
//        *   Redistributions in binary form must reproduce the above 
//            copyright notice, this list of conditions and the following 
//            disclaimer in the documentation and/or other materials 
//            provided with the distribution. 
//        *   Neither the name of the FEAPI development team nor the names 
//            of its contributors may be used to endorse or promote products 
//            derived from this software without specific prior written 
//            permission. 
//
//        THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
//        "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
//        LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
//        FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
//        COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
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//

#include <string.h>
#include <math.h>

#include "zplVecLib.h"

#if !defined(_2PI)
#define _2PI                    (float)(6.283185307179586476925286766559)    
#endif

void CzplfFFT_If::CalculateWindow (_Fft_Windows_ eWindowType)
{
    int i = 0;

    ZASSERT (!m_pfWindow);
    ZASSERT (m_iBlockLength < 4);

    switch (eWindowType)   
    {
    default:
    case _RECT:
        {
            for (i = 0; i < m_iBlockLength; i++)
                m_pfWindow[i]   = 1.0F;
            break;
        }
    case _HANNING:
        {
            // note that this is symmetric, not periodic!
            for (i = 0; i < m_iBlockLength; i++)
                m_pfWindow[i]   = .5F * (1.0F - cosf (_2PI * (i+1) / (m_iBlockLength+1)));
            break;
        }
    case _HAMMING:
        {
            // note that this is symmetric, not periodic!
            for (i = 0; i < m_iBlockLength; i++)
                m_pfWindow[i]   = .54F - .46F * cosf (_2PI * i / (m_iBlockLength-1));
            break;
        }
    case _BLACKMAN:
        {
            // note that this is symmetric, not periodic!
            for (i = 0; i < m_iBlockLength; i++)
                m_pfWindow[i]   = .42F - .5F * cosf (_2PI * i / (m_iBlockLength-1)) + .08F * cosf (2*_2PI * i / (m_iBlockLength-1));
            break;
        }
    case _BARTLETT:
        {
            // note that this is symmetric, not periodic!
            for (i = 0; i < (m_iBlockLength>>1); i++)
            {
                m_pfWindow[i]                       =  1 - (-i + (m_iBlockLength-1)*.5F) / (.5F*(m_iBlockLength-1));
                m_pfWindow[m_iBlockLength - 1 - i]  = m_pfWindow[i];
            }
            break;
        }
    case _WELCH:
        {
            // note that this is symmetric, not periodic!
            for (i = 0; i < (m_iBlockLength>>1); i++)
            {
                m_pfWindow[i]                       =  1 - (-i + (m_iBlockLength-1)*.5F) / (.5F*(m_iBlockLength-1));
                m_pfWindow[i]                      *= m_pfWindow[i];
                m_pfWindow[m_iBlockLength - 1 - i]  = m_pfWindow[i];
            }
            break;
        }
    }
}

unsigned int CzplfFFT_If::Log2 (int iValueAsPowOf2)
{
    unsigned int    iOrder = 0;

    while (iValueAsPowOf2>>iOrder)
        iOrder++;

    if (!(iValueAsPowOf2%(1<<(iOrder-1))))
        iOrder--;
    
    return iOrder;
}

int CzplfFFT_If::zplfGetWindow (float *pfWindow)
{
    if (!pfWindow)
        return m_iBlockLength;
    else
    {
        memcpy (pfWindow, m_pfWindow, sizeof(float) * m_iBlockLength);
        return m_iBlockLength;
    }
}

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