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// This is a simple test case of making an simple graph with a DLSSynth, Limiter and Ouput unit

// we're going to use a graph because its easier for it to just handle the setup and connections, etc...

#include <CoreServices/CoreServices.h> //for file stuff

#include <AudioUnit/AudioUnit.h>

#include <AudioToolbox/AudioToolbox.h> //for AUGraph

#include <unistd.h> // used for usleep...

// This call creates the Graph and the Synth unit...

OSStatus    CreateAUGraph (AUGraph &outGraph, AudioUnit &outSynth)

{

    OSStatus result;

    //create the nodes of the graph

    AUNode synthNode, limiterNode, outNode;

    AudioComponentDescription cd;

    cd.componentManufacturer = kAudioUnitManufacturer_Apple;

    cd.componentFlags = 0;

    cd.componentFlagsMask = 0;

    require_noerr (result = NewAUGraph (&outGraph), home);

    cd.componentType = kAudioUnitType_MusicDevice;

    cd.componentSubType = kAudioUnitSubType_DLSSynth;

    require_noerr (result = AUGraphAddNode (outGraph, &cd, &synthNode), home);

    cd.componentType = kAudioUnitType_Effect;

    cd.componentSubType = kAudioUnitSubType_PeakLimiter;  

    require_noerr (result = AUGraphAddNode (outGraph, &cd, &limiterNode), home);

    cd.componentType = kAudioUnitType_Output;

    cd.componentSubType = kAudioUnitSubType_DefaultOutput;  

    require_noerr (result = AUGraphAddNode (outGraph, &cd, &outNode), home);

    require_noerr (result = AUGraphOpen (outGraph), home);

    require_noerr (result = AUGraphConnectNodeInput (outGraph, synthNode, 0, limiterNode, 0), home);

    require_noerr (result = AUGraphConnectNodeInput (outGraph, limiterNode, 0, outNode, 0), home);

    // ok we're good to go - get the Synth Unit...

    require_noerr (result = AUGraphNodeInfo(outGraph, synthNode, 0, &outSynth), home);

home:

    return result;

}

// some MIDI constants:

enum {

    kMidiMessage_ControlChange      = 0xB,

    kMidiMessage_ProgramChange      = 0xC,

    kMidiMessage_BankMSBControl     = 0,

    kMidiMessage_BankLSBControl     = 32,

    kMidiMessage_NoteOn             = 0x9

};

int main (int argc, const char * argv[]) {

    AUGraph graph = 0;

    AudioUnit synthUnit;

    OSStatus result;

    char* bankPath = 0;

    UInt8 midiChannelInUse = 0; //we're using midi channel 1...

        // this is the only option to main that we have...

        // just the full path of the sample bank...

        // On OS X there are known places were sample banks can be stored

        // Library/Audio/Sounds/Banks - so you could scan this directory and give the user options

        // about which sample bank to use...

    if (argc > 1)

        bankPath = const_cast<char*>(argv[1]);

    require_noerr (result = CreateAUGraph (graph, synthUnit), home);

// if the user supplies a sound bank, we'll set that before we initialize and start playing

    if (bankPath) 

    {

        FSRef fsRef;

        require_noerr (result = FSPathMakeRef ((const UInt8*)bankPath, &fsRef, 0), home);

        printf ("Setting Sound Bank:%s\n", bankPath);

        require_noerr (result = AudioUnitSetProperty (synthUnit,

                                            kMusicDeviceProperty_SoundBankFSRef,

                                            kAudioUnitScope_Global, 0,

                                            &fsRef, sizeof(fsRef)), home);

    }

    // ok we're set up to go - initialize and start the graph

    require_noerr (result = AUGraphInitialize (graph), home);

        //set our bank

    require_noerr (result = MusicDeviceMIDIEvent(synthUnit, 

                                kMidiMessage_ControlChange << 4 | midiChannelInUse, 

                                kMidiMessage_BankMSBControl, 0,

                                0/*sample offset*/), home);

    require_noerr (result = MusicDeviceMIDIEvent(synthUnit, 

                                kMidiMessage_ProgramChange << 4 | midiChannelInUse, 

                                0/*prog change num*/, 0,

                                0/*sample offset*/), home);

    CAShow (graph); // prints out the graph so we can see what it looks like...

    require_noerr (result = AUGraphStart (graph), home);

    // we're going to play an octave of MIDI notes: one a second

    for (int i = 0; i < 13; i++) {

        UInt32 noteNum = i + 60;

        UInt32 onVelocity = 127;

        UInt32 noteOnCommand =  kMidiMessage_NoteOn << 4 | midiChannelInUse;

            printf ("Playing Note: Status: 0x%lX, Note: %ld, Vel: %ld\n", noteOnCommand, noteNum, onVelocity);

        require_noerr (result = MusicDeviceMIDIEvent(synthUnit, noteOnCommand, noteNum, onVelocity, 0), home);

            // sleep for a second

        usleep (1 * 1000 * 1000);

        require_noerr (result = MusicDeviceMIDIEvent(synthUnit, noteOnCommand, noteNum, 0, 0), home);

    }

    // ok we're done now

home:

    if (graph) {

        AUGraphStop (graph); // stop playback - AUGraphDispose will do that for us but just showing you what to do

        DisposeAUGraph (graph);

    }

    return result;

}