libcm/cmAudioSys.h

/// \file cmAudioSys.h
/// \brief Implements a real-time audio processing engine.
///
/// The audio system is composed a collection of independent sub-systems.
/// Each sub-system maintains a thread which runs asynchrounsly
/// from the application, the MIDI devices, and the audio devices.
/// To faciliate communication between these components each sub-system maintains 
/// two thread-safe data buffers one for control information and a second 
/// for audio data.
///
/// The audio devices are the primary driver for the system. 
/// Callbacks from the audio devices (See #cmApCallbackPtr_t) 
/// inserts incoming audio samples into the audio
/// record buffers and extracts samples from the playback buffer.  
/// When sufficient incoming samples and outgoing empty buffer space exists
/// a sub-system thread is waken up by the callback. This triggers a DSP audio 
/// processing cycle which empties/fills the audio buffers. During a DSP
/// processing cycle control messages from the application and MIDI are blocked and
/// buffered. Upon completetion of the DSP cycle a control message
/// transfer cycles occurs - buffered incoming messages are passed to 
/// the DSP system and messages originating in the DSP system are
/// buffered by the audio system for later pickup by the application
/// or MIDI system.
/// 
/// Note that control messages that arrive when the DSP cycle is not
/// occurring can pass directly through to the DSP system.
///
/// The DSP system sends messages back to the host by calling
/// cmAsDspToHostFunc_t provided by cmAudioSysCtx_t. These
/// calls are always made from within an audio system call to 
/// audio or control update within cmAsCallback_t. cmAsDspToHostFunc_t
/// simply stores the message in a message buffer.  The host picks
/// up the message at some later time when it notices that messages
/// are waiting via polling cmAudioSysIsMsgWaiting().
///
/// Implementation: \n
/// The audio sub-systems work by maintaining an internal thread
/// which blocks on a mutex condition variable.
/// While the thread is blocked the mutex is unlocked allowing messages
/// to pass directly through to the DSP procedure via cmAsCallback().
///
/// Periodic calls from running audio devices update the audio buffer. 
/// When the audio buffer has input samples waiting and output space
/// available the condition variable is signaled, the mutex is 
/// then automatically locked by the system, and the DSP execution
/// procedure is called via cmAsCallback().
///
/// Messages arriving while the mutex is locked are queued and
/// delivered to the DSP procedure at the end of the DSP execution
/// procedure.
///
/// Usage example and testing code:
/// See  cmAudioSysTest().
/// \snippet cmAudioSys.c cmAudioSysTest

#ifndef cmAudioSys_h
#define cmAudioSys_h

#ifdef __cplusplus
extern "C" {
#endif

  /// Audio system result codes
  enum
  {
    kOkAsRC = cmOkRC,
    kThreadErrAsRC,
    kMutexErrAsRC,
    kTsQueueErrAsRC,
    kMsgEnqueueFailAsRC,
    kAudioDevSetupErrAsRC,
    kAudioBufSetupErrAsRC,
    kAudioDevStartFailAsRC,
    kAudioDevStopFailAsRC,
    kBufTooSmallAsRC,
    kNoMsgWaitingAsRC,
    kMidiSysFailAsRC,
    kMsgSerializeFailAsRC,
    kStateBufFailAsRC,
    kInvalidArgAsRC,
    kNotInitAsRC
  };

  typedef cmHandle_t cmAudioSysH_t;  ///< Audio system handle type
  typedef unsigned   cmAsRC_t;       ///< Audio system result code

  struct cmAudioSysCtx_str;

  ///
  /// DSP system callback function.
  ///
  /// This is the sole point of entry into the DSP system while the audio system is running.
  ///
  /// ctxPtr is pointer to a cmAudioSysCtx_t record.
  ///
  /// This function is called under two circumstances:
  ///
  /// 1) To notify the DSP system that the audio input/output buffers need to be serviced.
  /// This is a perioidic request which the DSP system uses as its execution trigger.
  /// The msgByteCnt argument is set to zero to indicate this type of call.  
  ///
  /// 2) To pass messages from the host application to the DSP system.
  /// The DSP system is asyncronous with the host because it executes in the audio system thread
  /// rather than the host thread.  The cmAudioSysDeliverMsg() function synchronizes incoming
  /// messages with the internal audio system thread to prevent thread collisions.
  ///
  /// Notes:
  /// This callback is always made with the internal audio system mutex locked.
  ///
  /// The signal time covered by the callback is from 
  /// ctx->begSmpIdx to ctx->begSmpIdx+cfg->dspFramesPerCycle.
  ///
  /// The return value is currently not used.
  typedef cmRC_t (*cmAsCallback_t)(void* ctxPtr, unsigned msgByteCnt, const void* msgDataPtr );

  
  /// Audio device sub-sytem configuration record 
  typedef struct
  {
    cmRpt_t*       rpt;               ///< system console object
    unsigned       inDevIdx;          ///< input audio device
    unsigned       outDevIdx;         ///< output audio device
    bool           syncInputFl;       ///< true/false sync the DSP update callbacks with audio input/output
    unsigned       msgQueueByteCnt;   ///< Size of the internal msg queue used to buffer msgs arriving via cmAudioSysDeliverMsg().
    unsigned       devFramesPerCycle; ///< (512) Audio device samples per channel per device update buffer.
    unsigned       dspFramesPerCycle; ///< (64)  Audio samples per channel per DSP cycle.
    unsigned       audioBufCnt;       ///< (3)   Audio device buffers.
    double         srate;             ///< Audio sample rate.
  } cmAudioSysArgs_t;

  /// Audio sub-system configuration record.
  /// This record is provided by the host to configure the audio system
  /// via cmAudioSystemAllocate() or cmAudioSystemInitialize().
  typedef struct cmAudioSysSubSys_str
  {
    cmAudioSysArgs_t args;              ///< Audio device configuration
    cmAsCallback_t   cbFunc;            ///< DSP system entry point function.
    void*            cbDataPtr;         ///< Host provided data for the DSP system callback.   
  } cmAudioSysSubSys_t;


  /// Signature of a callback function provided by the audio system to receive messages 
  /// from the DSP system for later dispatch to the host application.
  /// This declaration is used by the DSP system implementation and the audio system.
  /// Note that this function is intended to convey one message broken into multiple parts.
  /// See cmTsQueueEnqueueSegMsg() for the equivalent interface.
  typedef cmAsRC_t (*cmAsDspToHostFunc_t)(struct cmAudioSysCtx_str* p, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt);

  /// Informational record passed with each call to the DSP callback function cmAsCallback_t
  typedef struct cmAudioSysCtx_str
  {
    void*               reserved;      ///< used internally by the system

    bool                audioRateFl;

    unsigned            srcNetNodeId;  ///<
    unsigned            asSubIdx;      ///< index of the sub-system this DSP process is serving

    cmAudioSysSubSys_t* ss;            ///< ptr to a copy of the cfg recd used to initialize the audio system
    unsigned            begSmpIdx;     ///< gives signal time as a sample count

    cmAsDspToHostFunc_t dspToHostFunc; ///< Callback used by the DSP process to send messages to the host
                                       ///< via the audio system. Returns a cmAsRC_t result code.

                                       ///< output (playback) buffers
    cmSample_t**        oChArray;      ///< each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
    unsigned            oChCnt;        ///< count of output channels (ele's in oChArray[])

                                       ///< input (recording) buffers
    cmSample_t**        iChArray;      ///< each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
    unsigned            iChCnt;        ///< count of input channels (ele's in iChArray[])
    
  } cmAudioSysCtx_t;

  /*
  typedef struct
  {
    const cmChar_t* devLabel;
    const cmChar_t* inAudioFn;
    const cmChar_t* outAudioFn;
    unsigned        oBits;
    unsigned        oChCnt;
  } cmAudioSysFilePort_t;
  */

  /// Audio system configuration record used by cmAudioSysAllocate().
  typedef struct cmAudioSysCfg_str
  {
    cmAudioSysSubSys_t*   ssArray;      ///< sub-system cfg record array
    unsigned              ssCnt;        ///< count of sub-systems   
    //cmAudioSysFilePort_t* afpArray;     ///< audio port file cfg recd array
    //unsigned              afpCnt;       ///< audio port file cnt
    unsigned              meterMs;      ///< Meter sample period in milliseconds
    void*                 clientCbData; ///< User arg. for clientCbFunc().
    cmTsQueueCb_t         clientCbFunc; ///< Called by  cmAudioSysReceiveMsg() to deliver internally generated msg's to the host. 
                                        ///  Set to NULL if msg's will be directly returned by buffers passed to cmAudioSysReceiveMsg().
    cmUdpNetH_t           netH;
  } cmAudioSysCfg_t;

  extern cmAudioSysH_t cmAudioSysNullHandle;

  /// Allocate and initialize an audio system as a collection of 'cfgCnt' sub-systems.
  /// Notes:
  /// The audio ports system must be initalized (via cmApInitialize()) prior to calling cmAudioSysAllocate().
  /// The MIDI port system must be initialized (via cmMpInitialize()) prior to calling cmAudioSysAllocate().
  /// Furthermore cmApFinalize() and cmMpFinalize() cannot be called prior to cmAudioSysFree().
  /// See cmAudioSystemTest() for a complete example.
  cmAsRC_t  cmAudioSysAllocate( cmAudioSysH_t* hp, cmRpt_t* rpt, const cmAudioSysCfg_t* cfg  );

  /// Finalize and release any resources held by the audio system.
  cmAsRC_t  cmAudioSysFree( cmAudioSysH_t* hp );

  /// Returns true if 'h' is a handle which was successfully allocated by cmAudioSysAllocate().
  bool      cmAudioSysHandleIsValid( cmAudioSysH_t h );

  /// Reinitialize a previously allocated audio system.  This function
  /// begins with a call to cmAudioSysFinalize().   
  /// Use cmAudioSysEnable(h,true) to begin processing audio following this call.
  cmAsRC_t  cmAudioSysInitialize( cmAudioSysH_t h, const cmAudioSysCfg_t* cfg );

  /// Complements cmAudioSysInitialize(). In general there is no need to call this function
  /// since calls to cmAudioSysInitialize() and cmAudioSysFree() automaticatically call it.
  cmAsRC_t  cmAudioSysFinalize( cmAudioSysH_t h );

  /// Returns true if the audio system has been successfully initialized.
  bool     cmAudioSysIsInitialized( cmAudioSysH_t );

  /// Returns true if the audio system is enabled.
  bool      cmAudioSysIsEnabled( cmAudioSysH_t h );

  /// Enable/disable the audio system.  Enabling the starts audio stream
  /// in/out of the system.
  cmAsRC_t  cmAudioSysEnable( cmAudioSysH_t h, bool enableFl );

  /// \name Host to DSP delivery functions
  /// @{

  /// Deliver a message from the host application to the DSP process. (host -> DSP);
  /// The message is formed as a concatenation of the bytes in each of the segments
  /// pointed to by 'msgDataPtrArrary[segCnt][msgByteCntArray[segCnt]'.
  /// This is the canonical msg delivery function in so far as the other host->DSP
  /// msg delivery function are written in terms of this function.
  /// The first 4 bytes in the first segment must contain the index of the audio sub-system
  /// which is to receive the message.
  cmAsRC_t  cmAudioSysDeliverSegMsg(  cmAudioSysH_t h, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt, unsigned srcNetNodeId );

  /// Deliver a single message from the host to the DSP system.
  cmAsRC_t  cmAudioSysDeliverMsg(   cmAudioSysH_t h,  const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );

  /// Deliver a single message from the host to the DSP system.
  /// Prior to delivery the 'id' is prepended to the message.
  cmAsRC_t  cmAudioSysDeliverIdMsg(  cmAudioSysH_t h, unsigned asSubIdx, unsigned id, const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );
  ///@}

  /// \name DSP to Host message functions
  /// @{

  /// Is a msg from the DSP waiting to be picked up by the host?  (host <- DSP)
  /// 0  = no msgs are waiting or the msg queue is locked by the DSP process.
  /// >0 = the size of the buffer required to hold the next msg returned via 
  /// cmAudioSysReceiveMsg().
  unsigned  cmAudioSysIsMsgWaiting(  cmAudioSysH_t h );

  /// Copy the next available msg sent from the DSP process to the host into the host supplied msg buffer
  /// pointed to by 'msgBufPtr'.  Set 'msgDataPtr' to NULL to receive msg by callback from cmAudioSysCfg_t.clientCbFunc.
  /// Returns kBufTooSmallAsRC if msgDataPtr[msgByteCnt] is too small to hold the msg.
  /// Returns kNoMsgWaitingAsRC if no messages are waiting for delivery or the msg queue is locked by the DSP process.
  /// Returns kOkAsRC if a msg was delivered.
  /// Call cmAudioSysIsMsgWaiting() prior to calling this function to get
  /// the size of the data buffer required to hold the next message.
  cmAsRC_t  cmAudioSysReceiveMsg(    cmAudioSysH_t h,  void* msgDataPtr, unsigned msgByteCnt );
  /// @}


  /// Fill an audio system status record.
  void      cmAudioSysStatus(  cmAudioSysH_t h, unsigned asSubIdx, cmAudioSysStatus_t* statusPtr );

  /// Enable cmAudioSysStatus_t notifications to be sent periodically to the host.
  /// Set asSubIdx to cmInvalidIdx to enable/disable all sub-systems.
  /// The notifications occur approximately every cmAudioSysCfg_t.meterMs milliseconds.
  void cmAudioSysStatusNotifyEnable( cmAudioSysH_t, unsigned asSubIdx, bool enableFl );

  /// Return a pointer the context record associated with a sub-system
  cmAudioSysCtx_t* cmAudioSysContext( cmAudioSysH_t h, unsigned asSubIdx );

  /// Return the count of audio sub-systems.
  /// This is the same as the count of cfg recds passed to cmAudioSystemInitialize().
  unsigned cmAudioSysSubSystemCount( cmAudioSysH_t h );

  /// Audio system test and example function.
  void      cmAudioSysTest( cmRpt_t* rpt, int argc, const char* argv[] );



#ifdef __cplusplus
}
#endif

#endif