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/* GSL - Generic Sound Layer
* Copyright (C) 2001-2002 Tim Janik and Stefan Westerfeld
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This library 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 Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "gslsignal.h"
#include "gslcommon.h"
/* --- frequency modulation --- */
void
gsl_frequency_modulator (const GslFrequencyModulator *fm,
guint n_values,
const gfloat *ifreq,
const gfloat *ifmod,
gfloat *fm_buffer)
{
gfloat *bound, fine_tune, fm_strength;
gboolean with_fine_tune;
fine_tune = gsl_cent_factor (fm->fine_tune);
with_fine_tune = fm->fine_tune != 0;
fm_strength = fm->fm_strength;
bound = fm_buffer + n_values;
if (ifreq && ifmod)
{
if (fm->exponential_fm)
{
if (with_fine_tune)
do {
*fm_buffer++ = *ifreq++ * gsl_approx_exp2 (fm_strength * *ifmod++) * fine_tune;
} while (fm_buffer < bound);
else
do {
*fm_buffer++ = *ifreq++ * gsl_approx_exp2 (fm_strength * *ifmod++);
} while (fm_buffer < bound);
}
else
{
if (with_fine_tune)
do {
*fm_buffer++ = *ifreq++ * (1 + fm_strength * *ifmod++) * fine_tune;
} while (fm_buffer < bound);
else
do {
*fm_buffer++ = *ifreq++ * (1 + fm_strength * *ifmod++);
} while (fm_buffer < bound);
}
}
else if (ifmod)
{
gfloat signal_freq = fm->signal_freq * fine_tune;
if (fm->exponential_fm)
do {
*fm_buffer++ = signal_freq * gsl_approx_exp2 (fm_strength * *ifmod++);
} while (fm_buffer < bound);
else
do {
*fm_buffer++ = signal_freq * (1 + fm_strength * *ifmod++);
} while (fm_buffer < bound);
}
else if (ifreq)
{
if (with_fine_tune)
do {
*fm_buffer++ = *ifreq++ * fine_tune;
} while (fm_buffer < bound);
else
do {
*fm_buffer++ = *ifreq++;
} while (fm_buffer < bound);
}
else
{
gfloat signal_freq = fm->signal_freq * fine_tune;
do {
*fm_buffer++ = signal_freq;
} while (fm_buffer < bound);
}
}
/* --- windows --- */
double
gsl_window_bartlett (double x) /* triangle */
{
if (fabs (x) > 1)
return 0;
return 1.0 - fabs (x);
}
double
gsl_window_blackman (double x)
{
if (fabs (x) > 1)
return 0;
return 0.42 + 0.5 * cos (GSL_PI * x) + 0.08 * cos (2.0 * GSL_PI * x);
}
double
gsl_window_cos (double x) /* von Hann window */
{
if (fabs (x) > 1)
return 0;
return 0.5 * cos (x * GSL_PI) + 0.5;
}
double
gsl_window_hamming (double x) /* sharp (rectangle) cutoffs at boundaries */
{
if (fabs (x) > 1)
return 0;
return 0.54 + 0.46 * cos (GSL_PI * x);
}
double
gsl_window_sinc (double x) /* noramlied C. Lanczos window */
{
if (fabs (x) > 1)
return 0;
x = x * GSL_PI;
if (fabs (x) < 1e-12)
return 1.0;
else
return sin (x) / x;
}
double
gsl_window_rect (double x) /* a square */
{
if (fabs (x) > 1)
return 0;
return 1.0;
}
/*
cos_roll_off(x)= x>fh?0:x<fl?1:cos(pi/2.*((fl-x)/(fh-fl)))
*/
/* --- cents & init --- */
const gdouble *gsl_cent_table = NULL;
#define GSL_2_RAISED_TO_1_OVER_1200_d ( /* 2^(1/1200) */ \
1.0005777895065548488418016859213821589946746826171875)
void
_gsl_init_signal (void)
{
static gdouble cent_table_space[201];
gint i;
/* cent table initialization,
* allow negative indexing within [-100..+100]
*/
gsl_cent_table = cent_table_space + 100;
for (i = -100; i <= 100; i++)
cent_table_space[100 + i] = pow (GSL_2_RAISED_TO_1_OVER_1200_d, i);
}
/* --- gsl_approx_atan1() --- */
double
gsl_approx_atan1_prescale (double boost_amount)
{
double max_boost_factor = 100; /* atan1(x*100) gets pretty close to 1 for x=1 */
double recip_tan_1_div_0_75 = 0.24202942695518667705824990442766; /* 1/tan(1/0.75) */
double scale;
g_return_val_if_fail (boost_amount >= 0 && boost_amount <= 1.0, 1.0);
/* scale boost_amount from [0..1] to -1..1 */
boost_amount = boost_amount * 2 - 1.0;
/* prescale factor for atan1(x*prescale), ranges from 1/max_boost_factor..max_boost_factor */
scale = pow (max_boost_factor, tan (boost_amount / 0.75) * recip_tan_1_div_0_75);
return scale;
}
/* --- exp2f() approximation taylor coefficients finder --- */
#if 0
#include <stdio.h>
double
exp2coeff (int n)
{
double r = 1;
int i;
for (i = 1; i <= n; i++)
{
r *= GSL_LN2;
r /= i;
}
return r;
}
/* generate taylor coefficients */
int
main (int argc,
char *argv[])
{
int i;
for (i = 0; i < 20; i++)
printf ("#define EXP2_TAYLOR_COEFF_%u\t(%.40f)\n", i, exp2coeff (i));
return 0;
}
/* test/bench program */
#define _GNU_SOURCE
#include <math.h>
int
main (int argc,
char *argv[])
{
double x, dummy = 0, l = 4;
if (1) /* print errors */
for (x = -3; x < 3.01; x += 0.1)
{
g_print ("%+f %+1.20f \t (%.20f - %.20f)\n",
x, exp (x * GSL_LN2) - gsl_signal_exp2 (x),
exp (x * GSL_LN2), gsl_signal_exp2 (x));
}
if (0) /* bench test */
for (x = -l; x < l; x += 0.000001)
{
dummy += gsl_signal_exp2 (x);
// dummy += exp2f (x);
}
g_print ("%f\r \n", dummy);
return 0;
}
#endif /* coeff generation */
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