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/*
* Copyright (c) 2008 MUSIC TECHNOLOGY GROUP (MTG)
* UNIVERSITAT POMPEU FABRA
*
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/*! \file tables.c
* \brief sin and sinc tables.
*
* contains functions for creating and indexing the tables
*/
#include "sms.h"
/*! \brief value to scale the sine-table-lookup phase */
static sfloat fSineScale;
/*! \brief inverse of fSineScale - turns a division into multiplication */
static sfloat fSineIncr;
/*! \brief value to scale the sinc-table-lookup phase */
static sfloat fSincScale;
/*! \brief global pointer to the sine table */
static sfloat *sms_tab_sine;
/*! \brief global pointer to the sinc table */
static sfloat *sms_tab_sinc;
/*! \brief prepares the sine table
* \param nTableSize size of table
* \return error code \see SMS_MALLOC in SMS_ERRORS
*/
int sms_prepSine(int nTableSize)
{
register int i;
sfloat fTheta;
sms_tab_sine = (sfloat *)malloc(nTableSize * sizeof(sfloat));
if(sms_tab_sine == NULL)
{
sms_error("Could not allocate memory for sine table");
return SMS_MALLOC;
}
fSineScale = (sfloat)(TWO_PI) / (sfloat)(nTableSize - 1);
fSineIncr = 1.0 / fSineScale;
fTheta = 0.0;
for(i = 0; i < nTableSize; i++)
{
fTheta = fSineScale * (sfloat)i;
sms_tab_sine[i] = sin(fTheta);
}
return SMS_OK;
}
/*! \brief clear sine table */
void sms_clearSine()
{
if(sms_tab_sine)
free(sms_tab_sine);
sms_tab_sine = NULL;
}
/*! \brief table-lookup sine method
* \param fTheta angle in radians
* \return approximately sin(fTheta)
*/
sfloat sms_sine(sfloat fTheta)
{
int i;
fTheta = fTheta - floor(fTheta * INV_TWO_PI) * TWO_PI;
if(fTheta < 0)
{
i = .5 - (fTheta * fSineIncr);
return -(sms_tab_sine[i]);
}
else
{
i = fTheta * fSineIncr + .5;
return sms_tab_sine[i];
}
}
/*! \brief Sinc method to generate the lookup table
*/
static sfloat Sinc(sfloat x, sfloat N)
{
return sinf((N/2) * x) / sinf(x/2);
}
/*! \brief prepare the Sinc table
*
* used for the main lobe of a frequency domain
* BlackmanHarris92 window
*
* \param nTableSize size of table
* \return error code \see SMS_MALLOC in SMS_ERRORS
*/
int sms_prepSinc(int nTableSize)
{
int i, m;
sfloat N = 512.0;
sfloat fA[4] = {.35875, .48829, .14128, .01168};
sfloat fMax = 0;
sfloat fTheta = -4.0 * TWO_PI / N;
sfloat fThetaIncr = (8.0 * TWO_PI / N) / (nTableSize);
sms_tab_sinc = (sfloat *)calloc(nTableSize, sizeof(sfloat));
if(sms_tab_sinc == NULL)
{
sms_error("Could not allocate memory for sinc table");
return (SMS_MALLOC);
}
for(i = 0; i < nTableSize; i++)
{
for (m = 0; m < 4; m++)
sms_tab_sinc[i] += -1 * (fA[m]/2) *
(Sinc (fTheta - m * TWO_PI/N, N) +
Sinc (fTheta + m * TWO_PI/N, N));
fTheta += fThetaIncr;
}
fMax = sms_tab_sinc[(int) nTableSize / 2];
for (i = 0; i < nTableSize; i++)
sms_tab_sinc[i] = sms_tab_sinc[i] / fMax;
fSincScale = (sfloat) nTableSize / 8.0;
return SMS_OK;
}
/*! \brief clear sine table */
void sms_clearSinc()
{
if(sms_tab_sinc)
free(sms_tab_sinc);
sms_tab_sinc = 0;
}
/*! \brief global sinc table-lookup method
*
* fTheta has to be from 0 to 8
*
* \param fTheta angle in radians
* \return approximately sinc(fTheta)
*/
sfloat sms_sinc(sfloat fTheta)
{
int index = (int) (.5 + fSincScale * fTheta);
return sms_tab_sinc[index];
}
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