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Version 4.4.0

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Gary Scavone
2013-09-29 23:11:39 +02:00
committed by Stephen Sinclair
parent d199342e86
commit eccd8c9981
287 changed files with 11712 additions and 7676 deletions
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87
include/BlitSaw.h
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@@ -1,3 +1,12 @@
#ifndef STK_BLITSAW_H
#define STK_BLITSAW_H
#include "Generator.h"
#include <cmath>
#include <limits>
namespace stk {
/***************************************************/
/*! \class BlitSaw
\brief STK band-limited sawtooth wave class.
@@ -19,11 +28,6 @@
*/
/***************************************************/
#ifndef STK_BLITSAW_H
#define STK_BLITSAW_H
#include "Generator.h"
class BlitSaw: public Generator
{
public:
@@ -54,10 +58,25 @@ class BlitSaw: public Generator
*/
void setHarmonics( unsigned int nHarmonics = 0 );
//! Return the last computed output value.
StkFloat lastOut( void ) const { return lastFrame_[0]; };
//! Compute and return one output sample.
StkFloat tick( void );
//! Fill a channel of the StkFrames object with computed outputs.
/*!
The \c channel argument must be less than the number of
channels in the StkFrames argument (the first channel is specified
by 0). However, range checking is only performed if _STK_DEBUG_
is defined during compilation, in which case an out-of-range value
will trigger an StkError exception.
*/
StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
protected:
void updateHarmonics( void );
StkFloat computeSample( void );
unsigned int nHarmonics_;
unsigned int m_;
@@ -70,4 +89,60 @@ class BlitSaw: public Generator
};
inline StkFloat BlitSaw :: tick( void )
{
// The code below implements the BLIT algorithm of Stilson and
// Smith, followed by a summation and filtering operation to produce
// a sawtooth waveform. After experimenting with various approaches
// to calculate the average value of the BLIT over one period, I
// found that an estimate of C2_ = 1.0 / period (in samples) worked
// most consistently. A "leaky integrator" is then applied to the
// difference of the BLIT output and C2_. (GPS - 1 October 2005)
// A fully optimized version of this code would replace the two sin
// calls with a pair of fast sin oscillators, for which stable fast
// two-multiply algorithms are well known. In the spirit of STK,
// which favors clarity over performance, the optimization has
// not been made here.
// Avoid a divide by zero, or use of a denormalized divisor
// at the sinc peak, which has a limiting value of m_ / p_.
StkFloat tmp, denominator = sin( phase_ );
if ( fabs(denominator) <= std::numeric_limits<StkFloat>::epsilon() )
tmp = a_;
else {
tmp = sin( m_ * phase_ );
tmp /= p_ * denominator;
}
tmp += state_ - C2_;
state_ = tmp * 0.995;
phase_ += rate_;
if ( phase_ >= PI ) phase_ -= PI;
lastFrame_[0] = tmp;
return lastFrame_[0];
}
inline StkFrames& BlitSaw :: tick( StkFrames& frames, unsigned int channel )
{
#if defined(_STK_DEBUG_)
if ( channel >= frames.channels() ) {
errorString_ << "BlitSaw::tick(): channel and StkFrames arguments are incompatible!";
handleError( StkError::FUNCTION_ARGUMENT );
}
#endif
StkFloat *samples = &frames[channel];
unsigned int hop = frames.channels();
for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
*samples = BlitSaw::tick();
return frames;
}
} // stk namespace
#endif