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/* logistic.cpp
A sample-and-hold logistic map control generator
(c) 2002 Nathaniel Virgo
Part of the Computer Music Toolkit - a library of LADSPA plugins.
The Computer Music Toolkit is Copyright (C) 2000-2002
Richard W.E. Furse. The author may be contacted at
richard@muse.demon.co.uk.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public Licence as
published by the Free Software Foundation; either version 2 of the
Licence, 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 General Public License
along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA. */
/*****************************************************************************/
#include <stdlib.h>
/*****************************************************************************/
#include "cmt.h"
#include "pinknoise.h"
#include "utils.h"
/*****************************************************************************/
namespace logistic {
enum {
port_r = 0,
port_frequency = 1,
port_output = 2,
n_ports = 3
};
/** This plugin uses the logistic map to generate periodic or
chaotic control signals. */
class Plugin : public CMT_PluginInstance {
private:
LADSPA_Data sample_rate;
LADSPA_Data x;
unsigned counter;
public:
Plugin(const LADSPA_Descriptor *,
unsigned long s_rate) :
CMT_PluginInstance(n_ports),
sample_rate(s_rate) {
}
~Plugin() {
}
friend void activate(LADSPA_Handle instance);
friend void run(LADSPA_Handle instance,
unsigned long sample_count);
};
void activate(LADSPA_Handle instance) {
Plugin *pp = (Plugin *) instance;
Plugin &p = *pp;
p.x = 0.3; // arbitrary non-zero value.
}
void run(LADSPA_Handle instance,
unsigned long sample_count) {
Plugin *pp = (Plugin *) instance;
Plugin &p = *pp;
LADSPA_Data r = *pp->m_ppfPorts[port_r];
LADSPA_Data frequency = *pp->m_ppfPorts[port_frequency];
LADSPA_Data * out = pp->m_ppfPorts[port_output];
frequency = BOUNDED_ABOVE(frequency,p.sample_rate);
r = BOUNDED_ABOVE(r,4);
unsigned remain = sample_count;
if (frequency > 0) {
while (remain) {
unsigned jump_samples = (remain<p.counter) ? remain : p.counter;
for (unsigned j=0; j<jump_samples; ++j) {
*(out++) = p.x*2-1;
}
p.counter -= jump_samples;
remain -= jump_samples;
if (p.counter==0) {
p.x = r*p.x*(1.0f - p.x);
p.counter = (unsigned)(p.sample_rate/frequency);
}
}
}
else
{
for (unsigned long i=0; i<sample_count; ++i)
*(out++) = p.x;
}
}
void initialise() {
CMT_Descriptor * d = new CMT_Descriptor
(1849,
"logistic",
0,
"Logistic Map Control Generator",
CMT_MAKER("Nathaniel Virgo"),
CMT_COPYRIGHT("2002", "Nathaniel Virgo"),
NULL,
CMT_Instantiate<Plugin>,
activate,
run,
NULL,
NULL,
NULL);
d->addPort
(LADSPA_PORT_INPUT | LADSPA_PORT_CONTROL,
"\"r\" parameter",
(LADSPA_HINT_BOUNDED_BELOW
| LADSPA_HINT_BOUNDED_ABOVE
| LADSPA_HINT_DEFAULT_MAXIMUM),
2.9, 3.9999);
d->addPort
(LADSPA_PORT_INPUT | LADSPA_PORT_CONTROL,
"Step frequency",
(LADSPA_HINT_BOUNDED_BELOW
| LADSPA_HINT_BOUNDED_ABOVE
| LADSPA_HINT_SAMPLE_RATE
| LADSPA_HINT_DEFAULT_MIDDLE),
0, 0.001);
d->addPort
(LADSPA_PORT_OUTPUT | LADSPA_PORT_AUDIO,
"Output");
registerNewPluginDescriptor(d);
}
} // end of namespace
/*****************************************************************************/
/* EOF */
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