/*

Copyright (C) 2016 Apple Inc. All Rights Reserved.

See LICENSE.txt for this sample’s licensing information

Abstract:

Tremolo Effect AU

*/

#include "AUEffectBase.h"

#include "TremoloUnitVersion.h"

#if AU_DEBUG_DISPATCHER

    #include "AUDebugDispatcher.h"

#endif

#ifndef __TremoloUnit_h__

#define __TremoloUnit_h__

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// Constants for parameters and  factory presets

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#pragma mark ____TremoloUnit Parameter Constants

// Provides the user interface name for the Frequency parameter.

static CFStringRef kParamName_Tremolo_Freq      = CFSTR ("Frequency");

// Defines a constant for the default value for the Frequency parameter, anticipating a 

//  unit of Hertz to be defined in the implementation file.

static const float kDefaultValue_Tremolo_Freq   = 2.0;

// Defines a constant for the minimum value for the Frequency parameter.

static const float kMinimumValue_Tremolo_Freq   = 0.5;

// Defines a constant for the maximum value for the Frequency parameter.

static const float kMaximumValue_Tremolo_Freq   = 20.0;

static CFStringRef kParamName_Tremolo_Depth     = CFSTR ("Depth");

static const float kDefaultValue_Tremolo_Depth  = 50.0;

static const float kMinimumValue_Tremolo_Depth  = 0.0;

static const float kMaximumValue_Tremolo_Depth  = 100.0;

static CFStringRef kParamName_Tremolo_Waveform  = CFSTR ("Waveform");

static const int kSineWave_Tremolo_Waveform     = 1;

static const int kSquareWave_Tremolo_Waveform   = 2;

static const int kDefaultValue_Tremolo_Waveform = kSineWave_Tremolo_Waveform;

// Defines menu item names for the waveform parameter

static CFStringRef kMenuItem_Tremolo_Sine       = CFSTR ("Sine");

static CFStringRef kMenuItem_Tremolo_Square     = CFSTR ("Square");

// Defines constants for identifying the parameters; defines the total number 

//  of parameters.

enum {

    kParameter_Frequency    = 0,

    kParameter_Depth        = 1,

    kParameter_Waveform     = 2,

    kNumberOfParameters     = 3

};

#pragma mark ____TremoloUnit Factory Preset Constants

// Defines a constant for the frequency value for the "Slow & Gentle" factory preset.

static const float kParameter_Preset_Frequency_Slow = 2.0;

// Defines a constant for the frequency value for the "Fast & Hard" factory preset.

static const float kParameter_Preset_Frequency_Fast = 20.0;

// Defines a constant for the depth value for the "Slow & Gentle" factory preset.

static const float kParameter_Preset_Depth_Slow     = 50.0;

// Defines a constant for the depth value for the "Fast & Hard" factory preset.

static const float kParameter_Preset_Depth_Fast     = 90.0;

// Defines a constant for the waveform value for the "Slow & Gentle" factory preset.

static const float kParameter_Preset_Waveform_Slow  = kSineWave_Tremolo_Waveform;

// Defines a constant for the waveform value for the "Fast & Hard" factory preset.

static const float kParameter_Preset_Waveform_Fast  = kSquareWave_Tremolo_Waveform;

enum {

    // Defines a constant for the "Slow & Gentle" factory preset.

    kPreset_Slow    = 0,

    // Defines a constant for the "Fast & Hard" factory preset.

    kPreset_Fast    = 1,

    // Defines a constant representing the total number of factory presets.

    kNumberPresets  = 2

};

// Defines an array containing two Core Foundation string objects. The objects contain 

//  values for the menu items in the user interface corresponding to the factory presets.

static AUPreset kPresets [kNumberPresets] = {

    {kPreset_Slow, CFSTR ("Slow & Gentle")},

    {kPreset_Fast, CFSTR ("Fast & Hard")}

};

// Defines a constant representing the default factory preset, in this case the 

//  "Slow & Gentle" preset.

static const int kPreset_Default = kPreset_Slow;

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// TremoloUnit class

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#pragma mark ____TremoloUnit

class TremoloUnit : public AUEffectBase {

public:

    TremoloUnit (AudioUnit component);

#if AU_DEBUG_DISPATCHER

    virtual ~TremoloUnit () {delete mDebugDispatcher;}

#endif

    virtual AUKernelBase *NewKernel () {return new TremoloUnitKernel(this);}

    virtual ComponentResult GetParameterValueStrings (

        AudioUnitScope          inScope,

        AudioUnitParameterID    inParameterID,

        CFArrayRef              *outStrings

    );

    virtual ComponentResult GetParameterInfo (

        AudioUnitScope          inScope,

        AudioUnitParameterID    inParameterID,

        AudioUnitParameterInfo  &outParameterInfo

    );

    virtual ComponentResult GetPropertyInfo (

        AudioUnitPropertyID     inID,

        AudioUnitScope          inScope,

        AudioUnitElement        inElement,

        UInt32                  &outDataSize,

        Boolean                 &outWritable

    );

    virtual ComponentResult GetProperty (

        AudioUnitPropertyID     inID,

        AudioUnitScope          inScope,

        AudioUnitElement        inElement,

        void                    *outData

    );

    // report that the audio unit supports the 

    //  kAudioUnitProperty_TailTime property

    virtual bool SupportsTail () {return true;}

    // provide the audio unit version information

    virtual ComponentResult Version () {return kTremoloUnitVersion;}

    // Declaration for the GetPresets method (for setting up the factory presets), 

    //  overriding the method from the AUBase superclass.

    virtual ComponentResult GetPresets (

        CFArrayRef  *outData

    ) const;

    // Declaration for the NewFactoryPresetSet method (for setting a factory preset 

    //  when requested by the host application), overriding the method from the 

    //  AUBase superclass.

    virtual OSStatus NewFactoryPresetSet (

        const AUPreset  &inNewFactoryPreset

    );

protected:

    class TremoloUnitKernel : public AUKernelBase {

        public:

            TremoloUnitKernel (AUEffectBase *inAudioUnit);

            // *Required* overides for the process method for this effect

            // processes one channel of interleaved samples

            virtual void Process (

                const Float32   *inSourceP,

                Float32         *inDestP,

                UInt32          inFramesToProcess,

                UInt32          inNumChannels, // equal to 1

                bool            &ioSilence

        );

        virtual void Reset ();

        private:

            enum    {kWaveArraySize = 2000};    // The number of points in the wave table.

            float   mSine [kWaveArraySize];     // The wave table for the tremolo sine wave.

            float   mSquare [kWaveArraySize];   // The wave table for the tremolo square wave.

            float   *waveArrayPointer;          // Points to the wave table to use for the current audio input buffer.

            Float32 mSampleFrequency;           // The "sample rate" of the audio signal being processed

            long    mSamplesProcessed;          // The number of samples processed since the audio unit

                                                //   started rendering or since this variable was last

                                                //   reset to 0. We have to keep track of this because

                                                //   we vary the tremolo continuously and independently

                                                //   of the input buffer size.

            enum    {sampleLimit = (int) 10E6}; // To keep the value of mSamplesProcessed within a 

                                                //   reasonable limit. 10E6 is equivalent to the number   

                                                //   of samples in 100 seconds of 96 kHz audio.

            float   mCurrentScale;              // There are two scaling factors to allow the audio unit

                                                //   to switch to a new scaling factor at the beginning

                                                //   of the tremolo waveform, no matter when the user

                                                //   changes the tremolo frequency. mCurrentScale is 

                                                //   the scaling factor in use.

            float   mNextScale;                 // The scaling factor that the user most recently requested

                                                //   by moving the tremolo frequency slider

    };

};

#endif