libcm is a C development framework with an emphasis on audio signal processing applications.
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cmRtSys.h 14KB

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  1. // cmRtSys.h
  2. // Implements a real-time audio processing engine.
  3. //
  4. // The audio system is composed a collection of independent sub-systems.
  5. // Each sub-system maintains a thread which runs asynchrounsly
  6. // from the application, the MIDI devices, and the audio devices.
  7. // To faciliate communication between these components each sub-system maintains
  8. // two thread-safe data buffers one for control information and a second
  9. // for audio data.
  10. //
  11. // The audio devices are the primary driver for the system.
  12. // Callbacks from the audio devices (See #cmApCallbackPtr_t)
  13. // inserts incoming audio samples into the audio
  14. // record buffers and extracts samples from the playback buffer.
  15. // When sufficient incoming samples and outgoing empty buffer space exists
  16. // a sub-system thread is waken up by the callback. This triggers a DSP audio
  17. // processing cycle which empties/fills the audio buffers. During a DSP
  18. // processing cycle control messages from the application and MIDI are blocked and
  19. // buffered. Upon completetion of the DSP cycle a control message
  20. // transfer cycles occurs - buffered incoming messages are passed to
  21. // the DSP system and messages originating in the DSP system are
  22. // buffered by the audio system for later pickup by the application
  23. // or MIDI system.
  24. //
  25. // Note that control messages that arrive when the DSP cycle is not
  26. // occurring can pass directly through to the DSP system.
  27. //
  28. // The DSP system sends messages back to the host by calling
  29. // cmRtDspToHostFunc_t provided by cmRtSysCtx_t. These
  30. // calls are always made from within an audio system call to
  31. // audio or control update within cmRtCallback_t. cmRtDspToHostFunc_t
  32. // simply stores the message in a message buffer. The host picks
  33. // up the message at some later time when it notices that messages
  34. // are waiting via polling cmRtSysIsMsgWaiting().
  35. //
  36. // Implementation: \n
  37. // The audio sub-systems work by maintaining an internal thread
  38. // which blocks on a mutex condition variable.
  39. // While the thread is blocked the mutex is unlocked allowing messages
  40. // to pass directly through to the DSP procedure via cmRtCallback().
  41. //
  42. // Periodic calls from running audio devices update the audio buffer.
  43. // When the audio buffer has input samples waiting and output space
  44. // available the condition variable is signaled, the mutex is
  45. // then automatically locked by the system, and the DSP execution
  46. // procedure is called via cmRtCallback().
  47. //
  48. // Messages arriving while the mutex is locked are queued and
  49. // delivered to the DSP procedure at the end of the DSP execution
  50. // procedure.
  51. //
  52. // Usage example and testing code:
  53. // See cmRtSysTest().
  54. // \snippet cmRtSys.c cmRtSysTest
  55. #ifndef cmRtSys_h
  56. #define cmRtSys_h
  57. #ifdef __cplusplus
  58. extern "C" {
  59. #endif
  60. // Audio system result codes
  61. enum
  62. {
  63. kOkRtRC = cmOkRC,
  64. kThreadErrRtRC,
  65. kMutexErrRtRC,
  66. kTsQueueErrRtRC,
  67. kMsgEnqueueFailRtRC,
  68. kAudioDevSetupErrRtRC,
  69. kAudioBufSetupErrRtRC,
  70. kAudioDevStartFailRtRC,
  71. kAudioDevStopFailRtRC,
  72. kBufTooSmallRtRC,
  73. kNoMsgWaitingRtRC,
  74. kMidiSysFailRtRC,
  75. kMsgSerializeFailRtRC,
  76. kStateBufFailRtRC,
  77. kInvalidArgRtRC,
  78. kNotInitRtRC,
  79. kTimeOutErrRtRC
  80. };
  81. enum
  82. {
  83. kAsDfltMsgQueueByteCnt = 0xffff,
  84. kAsDfltDevFramesPerCycle = 512,
  85. kAsDfltDspFramesPerCycle = 64,
  86. kAsDfltBufCnt = 3,
  87. kAsDfltSrate = 44100,
  88. kAsDfltSyncToInputFl = 1,
  89. kAsDfltMinMeterMs = 10,
  90. kAsDfltMeterMs = 50,
  91. kAsDfltMaxMeterMs = 1000
  92. };
  93. typedef cmHandle_t cmRtSysH_t; //< Audio system handle type
  94. typedef unsigned cmRtRC_t; //< Audio system result code
  95. struct cmRtSysCtx_str;
  96. //
  97. // DSP system callback function.
  98. //
  99. // This is the sole point of entry into the DSP system while the audio system is running.
  100. //
  101. // ctxPtr is pointer to a cmRtSysCtx_t record.
  102. //
  103. // This function is called under two circumstances:
  104. //
  105. // 1) To notify the DSP system that the audio input/output buffers need to be serviced.
  106. // This is a perioidic request which the DSP system uses as its execution trigger.
  107. // cmRtSysCtx_t.audioRateFl is set to true to indicate this type of callback.
  108. //
  109. // 2) To pass messages from the host application to the DSP system.
  110. // The DSP system is asyncronous with the host because it executes in the
  111. // audio system thread rather than the host thread. The cmRtSysDeliverMsg()
  112. // function synchronizes incoming messages with the internal audio system
  113. // thread to prevent thread collisions.
  114. //
  115. // Notes:
  116. // This callback is always made with the internal audio system mutex locked.
  117. //
  118. // The signal time covered by the callback is from
  119. // ctx->begSmpIdx to ctx->begSmpIdx+cfg->dspFramesPerCycle.
  120. //
  121. // The return value is currently not used.
  122. typedef cmRC_t (*cmRtCallback_t)(void* ctxPtr, unsigned msgByteCnt, const void* msgDataPtr );
  123. // Audio device sub-sytem configuration record
  124. typedef struct cmRtSysArgs_str
  125. {
  126. cmRpt_t* rpt; // system console object
  127. unsigned inDevIdx; // input audio device
  128. unsigned outDevIdx; // output audio device
  129. bool syncInputFl; // true/false sync the DSP update callbacks with audio input/output
  130. unsigned msgQueueByteCnt; // Size of the internal msg queue used to buffer msgs arriving via cmRtSysDeliverMsg().
  131. unsigned devFramesPerCycle; // (512) Audio device samples per channel per device update buffer.
  132. unsigned dspFramesPerCycle; // (64) Audio samples per channel per DSP cycle.
  133. unsigned audioBufCnt; // (3) Audio device buffers.
  134. double srate; // Audio sample rate.
  135. } cmRtSysArgs_t;
  136. // Audio sub-system configuration record.
  137. // This record is provided by the host to configure the audio system
  138. // via cmRtSystemAllocate() or cmRtSystemInitialize().
  139. typedef struct cmRtSysSubSys_str
  140. {
  141. cmRtSysArgs_t args; // Audio device configuration
  142. cmRtCallback_t cbFunc; // DSP system entry point function.
  143. void* cbDataPtr; // Host provided data for the DSP system callback.
  144. } cmRtSysSubSys_t;
  145. // Signature of a callback function provided by the audio system to receive messages
  146. // from the DSP system for later dispatch to the host application.
  147. // This declaration is used by the DSP system implementation and the audio system.
  148. // Note that this function is intended to convey one message broken into multiple parts.
  149. // See cmTsQueueEnqueueSegMsg() for the equivalent interface.
  150. typedef cmRtRC_t (*cmRtDspToHostFunc_t)(struct cmRtSysCtx_str* p, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt);
  151. // Record passed with each call to the DSP callback function cmRtCallback_t
  152. typedef struct cmRtSysCtx_str
  153. {
  154. void* reserved; // used internally by the audio system
  155. bool audioRateFl; // true if this is an audio update callback
  156. unsigned srcNetNodeId; // Source net node if this is a msg callback originating from a remote network node.
  157. unsigned rtSubIdx; // index of the sub-system this DSP process is serving
  158. cmRtSysSubSys_t* ss; // ptr to a copy of the cfg recd used to initialize the audio system
  159. unsigned begSmpIdx; // gives signal time as a sample count
  160. cmRtDspToHostFunc_t dspToHostFunc; // Callback used by the DSP process to send messages to the host
  161. // via the audio system. Returns a cmRtRC_t result code.
  162. // output (playback) buffers
  163. cmSample_t** oChArray; // each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
  164. unsigned oChCnt; // count of output channels (ele's in oChArray[])
  165. // input (recording) buffers
  166. cmSample_t** iChArray; // each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
  167. unsigned iChCnt; // count of input channels (ele's in iChArray[])
  168. } cmRtSysCtx_t;
  169. // Audio system configuration record used by cmRtSysAllocate().
  170. typedef struct cmRtSysCfg_str
  171. {
  172. cmRtSysSubSys_t* ssArray; // sub-system cfg record array
  173. unsigned ssCnt; // count of sub-systems
  174. unsigned meterMs; // Meter sample period in milliseconds
  175. void* clientCbData; // User arg. for clientCbFunc().
  176. cmTsQueueCb_t clientCbFunc; // Called by cmRtSysReceiveMsg() to deliver internally generated msg's to the host.
  177. // Set to NULL if msg's will be directly returned by buffers passed to cmRtSysReceiveMsg().
  178. cmUdpH_t udpH;
  179. } cmRtSysCfg_t;
  180. extern cmRtSysH_t cmRtSysNullHandle;
  181. // Allocate and initialize an audio system as a collection of 'cfgCnt' sub-systems.
  182. // Prior to call this function the audio audio ports system must be initalized
  183. // (via cmApInitialize()) and the MIDI port system must be initialized
  184. // (via cmMpInitialize()). Note also that cmApFinalize() and cmMpFinalize()
  185. // cannot be called prior to cmRtSysFree().
  186. // See cmRtSystemTest() for a complete example.
  187. cmRtRC_t cmRtSysAllocate( cmRtSysH_t* hp, cmRpt_t* rpt, const cmRtSysCfg_t* cfg );
  188. // Finalize and release any resources held by the audio system.
  189. cmRtRC_t cmRtSysFree( cmRtSysH_t* hp );
  190. // Returns true if 'h' is a handle which was successfully allocated by
  191. // cmRtSysAllocate().
  192. bool cmRtSysHandleIsValid( cmRtSysH_t h );
  193. // Reinitialize a previously allocated audio system. This function
  194. // begins with a call to cmRtSysFinalize().
  195. // Use cmRtSysEnable(h,true) to begin processing audio following this call.
  196. cmRtRC_t cmRtSysInitialize( cmRtSysH_t h, const cmRtSysCfg_t* cfg );
  197. // Complements cmRtSysInitialize(). In general there is no need to call this function
  198. // since calls to cmRtSysInitialize() and cmRtSysFree() automaticatically call it.
  199. cmRtRC_t cmRtSysFinalize( cmRtSysH_t h );
  200. // Returns true if the audio system has been successfully initialized.
  201. bool cmRtSysIsInitialized( cmRtSysH_t );
  202. // Returns true if the audio system is enabled.
  203. bool cmRtSysIsEnabled( cmRtSysH_t h );
  204. // Enable/disable the audio system. Enabling the starts audio stream
  205. // in/out of the system.
  206. cmRtRC_t cmRtSysEnable( cmRtSysH_t h, bool enableFl );
  207. //
  208. // DSP to Host delivery function
  209. //
  210. // This function is used to pass messages from a DSP process to the HOST it
  211. // is always called from within the real-time thread.
  212. cmRtRC_t cmRtSysDspToHostSegMsg( cmRtSysH_t h, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt);
  213. cmRtRC_t cmRtSysDspToHost( cmRtSysH_t h, const void* msgDataPtr, unsigned msgByteCnt);
  214. //
  215. // Host to DSP delivery functions
  216. //
  217. // Deliver a message from the host application to the DSP process. (host -> DSP);
  218. // The message is formed as a concatenation of the bytes in each of the segments
  219. // pointed to by 'msgDataPtrArrary[segCnt][msgByteCntArray[segCnt]'.
  220. // This is the canonical msg delivery function in so far as the other host->DSP
  221. // msg delivery function are written in terms of this function.
  222. // The first 4 bytes in the first segment must contain the index of the audio sub-system
  223. // which is to receive the message.
  224. cmRtRC_t cmRtSysDeliverSegMsg( cmRtSysH_t h, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt, unsigned srcNetNodeId );
  225. // Deliver a single message from the host to the DSP system.
  226. cmRtRC_t cmRtSysDeliverMsg( cmRtSysH_t h, const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );
  227. // Deliver a single message from the host to the DSP system.
  228. // Prior to delivery the 'id' is prepended to the message.
  229. cmRtRC_t cmRtSysDeliverIdMsg( cmRtSysH_t h, unsigned rtSubIdx, unsigned id, const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );
  230. //
  231. // DSP to Host message functions
  232. //
  233. // Is a msg from the DSP waiting to be picked up by the host? (host <- DSP)
  234. // 0 = no msgs are waiting or the msg queue is locked by the DSP process.
  235. // >0 = the size of the buffer required to hold the next msg returned via
  236. // cmRtSysReceiveMsg().
  237. unsigned cmRtSysIsMsgWaiting( cmRtSysH_t h );
  238. // Copy the next available msg sent from the DSP process to the host into the host supplied msg buffer
  239. // pointed to by 'msgBufPtr'. Set 'msgDataPtr' to NULL to receive msg by callback from cmRtSysCfg_t.clientCbFunc.
  240. // Returns kBufTooSmallRtRC if msgDataPtr[msgByteCnt] is too small to hold the msg.
  241. // Returns kNoMsgWaitingRtRC if no messages are waiting for delivery or the msg queue is locked by the DSP process.
  242. // Returns kOkRtRC if a msg was delivered.
  243. // Call cmRtSysIsMsgWaiting() prior to calling this function to get
  244. // the size of the data buffer required to hold the next message.
  245. cmRtRC_t cmRtSysReceiveMsg( cmRtSysH_t h, void* msgDataPtr, unsigned msgByteCnt );
  246. // Fill an audio system status record.
  247. void cmRtSysStatus( cmRtSysH_t h, unsigned rtSubIdx, cmRtSysStatus_t* statusPtr );
  248. // Enable cmRtSysStatus_t notifications to be sent periodically to the host.
  249. // Set rtSubIdx to cmInvalidIdx to enable/disable all sub-systems.
  250. // The notifications occur approximately every cmRtSysCfg_t.meterMs milliseconds.
  251. void cmRtSysStatusNotifyEnable( cmRtSysH_t, unsigned rtSubIdx, bool enableFl );
  252. // Return a pointer the context record associated with a sub-system
  253. cmRtSysCtx_t* cmRtSysContext( cmRtSysH_t h, unsigned rtSubIdx );
  254. // Return the count of audio sub-systems.
  255. // This is the same as the count of cfg recds passed to cmRtSystemInitialize().
  256. unsigned cmRtSysSubSystemCount( cmRtSysH_t h );
  257. // Audio system test and example function.
  258. void cmRtSysTest( cmRpt_t* rpt, int argc, const char* argv[] );
  259. #ifdef __cplusplus
  260. }
  261. #endif
  262. #endif