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stk::OnePole Class Reference

STK one-pole filter class. More...

`#include <OnePole.h>`

Inheritance diagram for stk::OnePole:

## Public Member Functions

| OnePole (StkFloat thePole=0.9)
| The default constructor creates a low-pass filter (pole at z = 0.9).
| ~OnePole ()
| Class destructor.
void | setB0 (StkFloat b0)
| Set the b[0] coefficient value.
void | setA1 (StkFloat a1)
| Set the a[1] coefficient value.
void | setCoefficients (StkFloat b0, StkFloat a1, bool clearState=false)
| Set all filter coefficients.
void | setPole (StkFloat thePole)
| Set the pole position in the z-plane.
StkFloat | lastOut (void) const
| Return the last computed output value.
StkFloat | tick (StkFloat input)
| Input one sample to the filter and return one output.
StkFrames & | tick (StkFrames &frames, unsigned int channel=0)
| Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
StkFrames & | tick (StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)
| Take a channel of the `iFrames` object as inputs to the filter and write outputs to the `oFrames` object.
Public Member Functions inherited from stk::Filter
| Filter (void)
| Class constructor.
unsigned int | channelsIn (void) const
| Return the number of input channels for the class.
unsigned int | channelsOut (void) const
| Return the number of output channels for the class.
virtual void | clear (void)
| Clears all internal states of the filter.
void | setGain (StkFloat gain)
| Set the filter gain.
StkFloat | getGain (void) const
| Return the current filter gain.
StkFloat | phaseDelay (StkFloat frequency)
| Return the filter phase delay at the specified frequency.
const StkFrames & | lastFrame (void) const
| Return an StkFrames reference to the last output sample frame.
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 one-pole filter class.

This class implements a one-pole digital filter. A method is provided for setting the pole position along the real axis of the z-plane while maintaining a constant peak filter gain.

by Perry R. Cook and Gary P. Scavone, 1995–2023.

## Member Function Documentation

## ◆ setPole()

void stk::OnePole::setPole | ( | StkFloat | thePole | ) |

Set the pole position in the z-plane.

This method sets the pole position along the real-axis of the z-plane and normalizes the coefficients for a maximum gain of one. A positive pole value produces a low-pass filter, while a negative pole value produces a high-pass filter. This method does not affect the filter gain value. The argument magnitude should be less than one to maintain filter stability.

## ◆ tick() [1/2]

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

inline virtual

Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.

The StkFrames argument reference is returned. 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::Filter.

90{
91#if defined(_STK_DEBUG_)
92 if ( channel >= frames.channels() ) {
93 oStream_ << "OnePole::tick(): channel and StkFrames arguments are incompatible!";
94 handleError( StkError::FUNCTION_ARGUMENT );
95 }
96#endif
97
98 StkFloat *samples = &frames[channel];
99 unsigned int hop = frames.channels();
100 for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) {
101 inputs_[0] = gain_ * *samples;
102 *samples = b_[0] * inputs_[0] - a_[1] * outputs_[1];
103 outputs_[1] = *samples;
104 }
105
106 lastFrame_[0] = outputs_[1];
107 return frames;
108}
stk::Stk::handleError
static void handleError(const char *message, StkError::Type type)
Static function for error reporting and handling using c-strings.

## ◆ tick() [2/2]

StkFrames & stk::OnePole::tick | ( | StkFrames & | iFrames,
|  | StkFrames & | oFrames,
|  | unsigned int | iChannel = 0,
|  | unsigned int | oChannel = 0 )

inline

Take a channel of the `iFrames` object as inputs to the filter and write outputs to the `oFrames` object.

The `iFrames` object reference is returned. Each channel argument must be less than the number of channels in the corresponding 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.

111{
112#if defined(_STK_DEBUG_)
113 if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
114 oStream_ << "OnePole::tick(): channel and StkFrames arguments are incompatible!";
115 handleError( StkError::FUNCTION_ARGUMENT );
116 }
117#endif
118
119 StkFloat *iSamples = &iFrames[iChannel];
120 StkFloat *oSamples = &oFrames[oChannel];
121 unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
122 for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) {
123 inputs_[0] = gain_ * *iSamples;
124 *oSamples = b_[0] * inputs_[0] - a_[1] * outputs_[1];
125 outputs_[1] = *oSamples;
126 }
127
128 lastFrame_[0] = outputs_[1];
129 return iFrames;
130}

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

- OnePole.h

The Synthesis ToolKit in C++ (STK)
©1995--2023 Perry R. Cook and Gary P. Scavone. All Rights Reserved.