/// Reserved DSP message selector id's (second field of all host&lt-&gtaudio system messages)
enum
{
  kMidiMsgArraySelAsId = 1000,
  kMidiSysExSelAsId,
  kUiSelAsId,       // indicates a cmDspUiHdr_t msg
  kUiMstrSelAsId,   // indicates a cmDspUiHdr_t msg containing master control information for the audio system
  kSsInitSelAsId,   // indicates the msg is of type cmAudioSysSsInitMsg_t
  kStatusSelAsId,   // indicates the msg is of type cmAudioSysStatus_t
  kNetSyncSelAsId,    // sent with a cmDspNetMsg_t object 
};

typedef struct
{
  unsigned asSubIdx;
  unsigned selAsId;   // Message selector id See kXXXSelAsId above
  unsigned selId;     // Message specific selector
} cmAudioSysMsg_t;

// All of the UI messages that create a UI control contain an array of integers
// as in the 'value' field. The array contains the id's associated with
// the different programmable paramters which are part of the control.
// For example a slider control has minimum,maximum, step size, and value 
// parameters. The location in the array is hard coded according to the
// parameters meaning but the actual value of the id is left up to the 
// engine. This allows the engine to use whatever values work best for
// it on a per instance basis. 


// Header record for all messages between the host and the DSP controllers.
typedef struct
{
  unsigned     asSubIdx;   // the audio sub-system this UI belongs to
  unsigned     uiId;       // msg type kXXXAsId 
  unsigned     selId;      // action to perform see above
  unsigned     flags;      
  unsigned     instId;     // DSP instance id
  unsigned     instVarId;  // DSP instance var id
  unsigned     rsrvd;
  double       value;
} cmAudioSysMstr_t;


/// The cmDspUiHdr_t.instId of UI control messages associated with master
/// control encode the device,channel,in/out, and control type. These macros
/// should be used for encoding and decoding.
#define cmAudioSysFormUiInstId(dev,ch,ifl,ctl) (((dev)<<16) + ((ch)<<4) + ((ifl)<<3) + (ctl))
#define cmAudioSysUiInstIdToDevIndex(instId)  ( (instId) >> 16)
#define cmAudioSysUiInstIdToChIndex(instId)   (((instId) &  0x0000ffff) >> 4)
#define cmAudioSysUiInstIdToInFlag(instId)    ( (instId) &  0x08)
#define cmAudioSysUiInstIdToCtlId(instId)     ( (instId) &  0x07)

/// Control id's used to identify the control type of master contols.
enum
{
  kSliderUiAsId = 0,
  kMeterUiAsId  = 1,
  kMuteUiAsId   = 2,
  kToneUiAsId   = 3,
  kPassUiAsId   = 4
};


/// This message is transmitted to the host application just prior to returning
/// from cmAudioSysInitialize().
/// When transmitted to the host this record acts as a message header.
/// This header is followed by two zero terminated char arrays containing the device
/// labels associated with the input and output devices.
/// Message Layout: [ cmAudioSysInitMsg_t &quotIn Device Label&quot &quotOut Device Label&quot]
typedef struct
{
  unsigned asSubIdx;   // /&lt asSubIdx of this sub-system
  unsigned selId;      // /&lt always kSsInitAsId
  unsigned asSubCnt;   // /&lt count of sub-systems
  unsigned inDevIdx;   // /&lt input device index
  unsigned outDevIdx;  // /&lt output device index
  unsigned dspFramesPerCycle;
  double   srate;
  unsigned inChCnt;    // /&lt input device channel count
  unsigned outChCnt;   // /&lt outut device channel count
} cmAudioSysSsInitMsg_t;

/// Audio sub-system status record - this message can be transmitted to the host at
/// periodic intervals.  See cmAudioSysStatusNotifyEnable().
/// When transmitted to the host this record acts as the message header.
/// This header is followed by two arrays of doubles containing the input and output meter values
/// associated with the input and output audio devices.
/// Message Layout: [ asSubIdx kStatusSelId cmAudioSysStatus_t iMeterArray[iMeterCnt] oMeterArray[oMeterCnt] ]
typedef struct
{
  unsigned asSubIdx;      // /&lt originating audio sub-system
  
  unsigned updateCnt;     // /&lt count of callbacks from the audio devices.
  unsigned wakeupCnt;     // /&lt count of times the audio system thread has woken up after the cond. var has been signaled by the audio update thread.
  unsigned msgCbCnt;      // /&lt count of msgs delivered via cmAsCallback() .
  unsigned audioCbCnt;    // /&lt count of times the DSP execution was requested via cmAsCallback(). 
  
  unsigned iDevIdx;       // /&lt Input device index
  unsigned oDevIdx;       // /&lt Output device index
  
  unsigned overflowCnt;   // /&lt count of times the audio input buffers overflowed
  unsigned underflowCnt;  // /&lt count of times the audio output buffers underflowed
  unsigned iMeterCnt;     // /&lt count of input meter channels
  unsigned oMeterCnt;     // /&lt count of output meter channels
  
} cmAudioSysStatus_t;