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+/*
+
+ Copyright (C) 2000 Jeff Tranter
+ tranter@pobox.com
+ Stefan Westerfeld
+ stefan@space.twc.de
+ Jens Hahn
+ Jens.Hahn@t-online.de
+ 2001 Matthias Kretz
+ kretz@kde.org
+
+ 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public License
+ along with this library; see the file COPYING.LIB. If not, write to
+ the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+
+ */
+
+#include "artsmodulessynth.h"
+#include "stdsynthmodule.h"
+
+#include <math.h>
+
+using namespace Arts;
+
+// This delays the input signal for an amount of time. The time
+// specification must be between 0 and 1 for a delay between 0 seconds
+// and 1 second.
+//
+// This kind of delay may not be used in feedback structures. This is
+// because it's a variable delay. You can modify it's length while it
+// is running, and even set it down to zero. But since in a feedback
+// structure the own output is needed to calculate the next samples, a
+// delay whose value could drop to zero during synthesis could lead to
+// a stall situation.
+//
+// Use CDELAYs in that setup, perhaps combine a small constant delay
+// (of 0.001 seconds) with a flexible delay.
+//
+// You can also combine a CDELAY and a DELAY to achieve a variable
+// length delay with a minimum value in a feedback loop. Just make
+// sure that you have a CDELAY involved.
+
+class Synth_DELAY_impl : virtual public Synth_DELAY_skel,
+ virtual public StdSynthModule
+{
+protected:
+ unsigned long _buffersize;
+ unsigned long _bitmask;
+ float * _buffer;
+ float _maxdelay;
+ unsigned int _writepos;
+
+public:
+ Synth_DELAY_impl() : _buffersize( 0 ), _bitmask( 0 ), _buffer( 0 ), _maxdelay( 0 ), _writepos( 0 )
+ {
+ maxdelay( 1 ); // take a one second buffer if nothing else is specified
+ }
+
+ ~Synth_DELAY_impl()
+ {
+ delete[] _buffer;
+ }
+
+ void streamInit()
+ {
+ // initialize buffer to all zeroes
+ for ( unsigned long i = 0; i < _buffersize; i++ )
+ _buffer[i] = 0.0;
+ }
+
+ void calculateBlock(unsigned long samples)
+ {
+ for( unsigned long i = 0; i <samples; i++ )
+ {
+ double int_pos;
+ double error = modf( time[i] * samplingRateFloat, &int_pos );
+ unsigned long readpos1 = ( _writepos - (unsigned long)(int_pos) ) & _bitmask;
+ unsigned long readpos2 = ( readpos1 - 1 ) & _bitmask; // Shouldn't this be +1? (mkretz)
+ // No, it's right this way:
+ // ( 1 - error ) needs to be multiplied with the second
+ // sample; error with the first
+ _buffer[_writepos] = invalue[i];
+ outvalue[i] = _buffer[readpos1] * ( 1 - error ) + _buffer[readpos2] * error;
+ _writepos++;
+ _writepos &= _bitmask;
+ }
+ }
+
+ float maxdelay() { return _maxdelay; }
+
+ void maxdelay(float newmaxdelay)
+ {
+ if( newmaxdelay <= 0 )
+ return;
+ _maxdelay = newmaxdelay;
+ double n = ceil( log( double(_maxdelay * samplingRateFloat) ) / log( 2. ) );
+ unsigned long newbuffersize = (unsigned long)( pow( 2, n ) );
+ unsigned long newbitmask = newbuffersize - 1;
+ if( newbuffersize != _buffersize )
+ {
+ float *newbuffer = new float[newbuffersize];
+ if( newbuffersize > _buffersize ) {
+ for( unsigned long i = 0; i < _buffersize; i++ ) {
+ newbuffer[i] = _buffer[_writepos];
+ _writepos++;
+ _writepos &= newbitmask;
+ }
+ for( unsigned long i = _buffersize; i < newbuffersize; i++ )
+ newbuffer[i] = 0;
+ } else {
+ _writepos -= newbuffersize;
+ _writepos &= newbitmask;
+ for( unsigned long i = 0; i < newbuffersize; i++ ) {
+ newbuffer[i] = _buffer[_writepos];
+ _writepos++;
+ _writepos &= newbitmask;
+ }
+ }
+ _buffer = newbuffer;
+ _buffersize = newbuffersize;
+ _bitmask = newbitmask;
+ }
+ maxdelay_changed( _maxdelay );
+ }
+};
+
+REGISTER_IMPLEMENTATION(Synth_DELAY_impl);