stk::BlitSaw Class Reference

STK band-limited sawtooth wave class. More...

#include <BlitSaw.h>

Inheritance diagram for stk::BlitSaw:

Public Member Functions
	BlitSaw (StkFloat frequency=220.0)
	Class constructor.
	~BlitSaw ()
	Class destructor.
void	reset ()
	Resets the oscillator state and phase to 0.
void	setFrequency (StkFloat frequency)
	Set the sawtooth oscillator rate in terms of a frequency in Hz.
void	setHarmonics (unsigned int nHarmonics=0)
	Set the number of harmonics generated in the signal.
StkFloat	lastOut (void) const
	Return the last computed output value.
StkFloat	tick (void)
	Compute and return one output sample.
StkFrames &	tick (StkFrames &frames, unsigned int channel=0)
	Fill a channel of the StkFrames object with computed outputs.
Public Member Functions inherited from stk::Generator
	Generator (void)
	Class constructor.
unsigned int	channelsOut (void) const
	Return the number of output channels for the class.
const StkFrames &	lastFrame (void) const
	Return an StkFrames reference to the last output sample frame.
virtual StkFrames &	tick (StkFrames &frames, unsigned int channel=0)=0
	Fill the StkFrames object with computed sample frames, starting at the specified channel.
Public Member Functions inherited from stk::Stk
void	ignoreSampleRateChange (bool ignore=true)
	A function to enable/disable the automatic updating of class data when the STK sample rate changes.

Additional Inherited Members
Static Public Member Functions inherited from stk::Stk
static StkFloat	sampleRate (void)
	Static method that returns the current STK sample rate.
static void	setSampleRate (StkFloat rate)
	Static method that sets the STK sample rate.
static void	clear_alertList ()
	Static method that frees memory from alertList_.
static std::string	rawwavePath (void)
	Static method that returns the current rawwave path.
static void	setRawwavePath (std::string path)
	Static method that sets the STK rawwave path.
static void	swap16 (unsigned char *ptr)
	Static method that byte-swaps a 16-bit data type.
static void	swap32 (unsigned char *ptr)
	Static method that byte-swaps a 32-bit data type.
static void	swap64 (unsigned char *ptr)
	Static method that byte-swaps a 64-bit data type.
static void	sleep (unsigned long milliseconds)
	Static cross-platform method to sleep for a number of milliseconds.
static bool	inRange (StkFloat value, StkFloat min, StkFloat max)
	Static method to check whether a value is within a specified range.
static void	handleError (const char *message, StkError::Type type)
	Static function for error reporting and handling using c-strings.
static void	handleError (std::string message, StkError::Type type)
	Static function for error reporting and handling using c++ strings.
static void	showWarnings (bool status)
	Toggle display of WARNING and STATUS messages.
static void	printErrors (bool status)
	Toggle display of error messages before throwing exceptions.
Static Public Attributes inherited from stk::Stk
static const StkFormat	STK_SINT8
static const StkFormat	STK_SINT16
static const StkFormat	STK_SINT24
static const StkFormat	STK_SINT32
static const StkFormat	STK_FLOAT32
static const StkFormat	STK_FLOAT64
Protected Member Functions inherited from stk::Stk
	Stk (void)
	Default constructor.
virtual	~Stk (void)
	Class destructor.
virtual void	sampleRateChanged (StkFloat newRate, StkFloat oldRate)
	This function should be implemented in subclasses that depend on the sample rate.
void	addSampleRateAlert (Stk *ptr)
	Add class pointer to list for sample rate change notification.
void	removeSampleRateAlert (Stk *ptr)
	Remove class pointer from list for sample rate change notification.
void	handleError (StkError::Type type) const
	Internal function for error reporting that assumes message in oStream_ variable.

Detailed Description

STK band-limited sawtooth wave class.

This class generates a band-limited sawtooth waveform using a closed-form algorithm reported by Stilson and Smith in "Alias-Free Digital Synthesis of Classic Analog Waveforms", 1996. The user can specify both the fundamental frequency of the sawtooth and the number of harmonics contained in the resulting signal.

If nHarmonics is 0, then the signal will contain all harmonics up to half the sample rate. Note, however, that this setting may produce aliasing in the signal when the frequency is changing (no automatic modification of the number of harmonics is performed by the setFrequency() function).

Based on initial code of Robin Davies, 2005. Modified algorithm code by Gary Scavone, 2005.

Member Function Documentation

setHarmonics()

void stk::BlitSaw::setHarmonics

(

unsigned int

nHarmonics = 0

)

Set the number of harmonics generated in the signal.

This function sets the number of harmonics contained in the resulting signal. It is equivalent to (2 * M) + 1 in the BLIT algorithm. The default value of 0 sets the algorithm for maximum harmonic content (harmonics up to half the sample rate). This parameter is not checked against the current sample rate and fundamental frequency. Thus, aliasing can result if one or more harmonics for a given fundamental frequency exceeds fs / 2. This behavior was chosen over the potentially more problematic solution of automatically modifying the M parameter, which can produce audible clicks in the signal.

tick()

StkFrames & stk::BlitSaw::tick ( StkFrames &  frames, unsigned int  channel = 0  )

inlinevirtual

Fill a channel of the StkFrames object with computed outputs.

The 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.

Implements stk::Generator.

{
#if defined(_STK_DEBUG_)
  if ( channel >= frames.channels() ) {
    oStream_ << "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;
}

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The documentation for this class was generated from the following file:

• BlitSaw.h