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. kNetErrRtRC
  81. };
  82. enum
  83. {
  84. kAsDfltMsgQueueByteCnt = 0xffff,
  85. kAsDfltDevFramesPerCycle = 512,
  86. kAsDfltDspFramesPerCycle = 64,
  87. kAsDfltBufCnt = 3,
  88. kAsDfltSrate = 44100,
  89. kAsDfltSyncToInputFl = 1,
  90. kAsDfltMinMeterMs = 10,
  91. kAsDfltMeterMs = 50,
  92. kAsDfltMaxMeterMs = 1000
  93. };
  94. typedef cmHandle_t cmRtSysH_t; //< Audio system handle type
  95. typedef unsigned cmRtRC_t; //< Audio system result code
  96. struct cmRtSysCtx_str;
  97. //
  98. // DSP system callback function.
  99. //
  100. // This is the sole point of entry into the DSP system while the audio system is running.
  101. //
  102. // ctxPtr is pointer to a cmRtSysCtx_t record.
  103. //
  104. // This function is called under two circumstances:
  105. //
  106. // 1) To notify the DSP system that the audio input/output buffers need to be serviced.
  107. // This is a perioidic request which the DSP system uses as its execution trigger.
  108. // cmRtSysCtx_t.audioRateFl is set to true to indicate this type of callback.
  109. //
  110. // 2) To pass messages from the host application to the DSP system.
  111. // The DSP system is asyncronous with the host because it executes in the
  112. // audio system thread rather than the host thread. The cmRtSysDeliverMsg()
  113. // function synchronizes incoming messages with the internal audio system
  114. // thread to prevent thread collisions.
  115. //
  116. // Notes:
  117. // This callback is always made with the internal audio system mutex locked.
  118. //
  119. // The signal time covered by the callback is from
  120. // ctx->begSmpIdx to ctx->begSmpIdx+cfg->dspFramesPerCycle.
  121. //
  122. // The return value is currently not used.
  123. typedef cmRC_t (*cmRtCallback_t)(void* ctxPtr, unsigned msgByteCnt, const void* msgDataPtr );
  124. // Network nodes
  125. typedef struct
  126. {
  127. const cmChar_t* label; // Remote node label or NULL if this is the local node.
  128. const cmChar_t* ipAddr; // IP address in xxx.xxx.xxx.xxx form or NULL for 'localhost'.
  129. cmUdpPort_t ipPort; // IP port
  130. } cmRtSysNetNode_t;
  131. // Local endpoints.
  132. typedef struct
  133. {
  134. const cmChar_t* label; // Local endpoint label
  135. unsigned id; // Local endpoint id
  136. } cmRtSysNetEndpt_t;
  137. // Audio device sub-sytem configuration record
  138. typedef struct cmRtSysArgs_str
  139. {
  140. cmRpt_t* rpt; // system console object
  141. unsigned inDevIdx; // input audio device
  142. unsigned outDevIdx; // output audio device
  143. bool syncInputFl; // true/false sync the DSP update callbacks with audio input/output
  144. unsigned msgQueueByteCnt; // Size of the internal msg queue used to buffer msgs arriving via cmRtSysDeliverMsg().
  145. unsigned devFramesPerCycle; // (512) Audio device samples per channel per device update buffer.
  146. unsigned dspFramesPerCycle; // (64) Audio samples per channel per DSP cycle.
  147. unsigned audioBufCnt; // (3) Audio device buffers.
  148. double srate; // Audio sample rate.
  149. } cmRtSysArgs_t;
  150. // Audio sub-system configuration record.
  151. // This record is provided by the host to configure the audio system
  152. // via cmRtSystemAllocate() or cmRtSystemInitialize().
  153. typedef struct cmRtSysSubSys_str
  154. {
  155. cmRtSysArgs_t args; // Audio device configuration
  156. cmRtCallback_t cbFunc; // DSP system entry point function.
  157. void* cbDataPtr; // Host provided data for the DSP system callback.
  158. cmRtSysNetNode_t* netNodeArray; // One node must be the local node.
  159. unsigned netNodeCnt; // Count of network nodes or 0 to not use network
  160. cmRtSysNetEndpt_t* endptArray; // Local end points
  161. unsigned endptCnt; // Count of local endpoints.
  162. } cmRtSysSubSys_t;
  163. // Signature of a callback function provided by the audio system to receive messages
  164. // from the DSP system for later dispatch to the host application.
  165. // This declaration is used by the DSP system implementation and the audio system.
  166. // Note that this function is intended to convey one message broken into multiple parts.
  167. // See cmTsQueueEnqueueSegMsg() for the equivalent interface.
  168. typedef cmRtRC_t (*cmRtDspToHostFunc_t)(struct cmRtSysCtx_str* p, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt);
  169. // Record passed with each call to the DSP callback function cmRtCallback_t
  170. typedef struct cmRtSysCtx_str
  171. {
  172. void* reserved; // used internally by the audio system
  173. bool audioRateFl; // true if this is an audio update callback
  174. unsigned srcNetNodeId; // Source net node if this is a msg callback originating from a remote network node.
  175. unsigned rtSubIdx; // index of the sub-system this DSP process is serving
  176. cmRtSysSubSys_t* ss; // ptr to a copy of the cfg recd used to initialize the audio system
  177. unsigned begSmpIdx; // gives signal time as a sample count
  178. cmRtDspToHostFunc_t dspToHostFunc; // Callback used by the DSP process to send messages to the host
  179. // via the audio system. Returns a cmRtRC_t result code.
  180. // output (playback) buffers
  181. cmSample_t** oChArray; // each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
  182. unsigned oChCnt; // count of output channels (ele's in oChArray[])
  183. // input (recording) buffers
  184. cmSample_t** iChArray; // each ele is a ptr to buffer with cfg.dspFramesPerCycle samples
  185. unsigned iChCnt; // count of input channels (ele's in iChArray[])
  186. } cmRtSysCtx_t;
  187. extern cmRtSysH_t cmRtSysNullHandle;
  188. // Allocate and initialize an audio system as a collection of 'cfgCnt' sub-systems.
  189. // Prior to call this function the audio audio ports system must be initalized
  190. // (via cmApInitialize()) and the MIDI port system must be initialized
  191. // (via cmMpInitialize()). Note also that cmApFinalize() and cmMpFinalize()
  192. // cannot be called prior to cmRtSysFree().
  193. // See cmRtSystemTest() for a complete example.
  194. cmRtRC_t cmRtSysAllocate( cmRtSysH_t* hp, cmCtx_t* ctx );
  195. // Finalize and release any resources held by the audio system.
  196. cmRtRC_t cmRtSysFree( cmRtSysH_t* hp );
  197. // Returns true if 'h' is a handle which was successfully allocated by
  198. // cmRtSysAllocate().
  199. bool cmRtSysHandleIsValid( cmRtSysH_t h );
  200. // clientCbFunc is Called by cmRtSysReceiveMsg() to deliver internally generated msg's to the host.
  201. // Set to NULL if msg's will be directly returned by buffers passed to cmRtSysReceiveMsg().
  202. cmRtRC_t cmRtSysBeginCfg( cmRtSysH_t h, cmTsQueueCb_t clientCbFunc, void* clientCbArg, unsigned meterMs, unsigned ssCnt );
  203. // Reinitialize a previously allocated audio system. This function
  204. // begins with a call to cmRtSysFinalize().
  205. // Use cmRtSysEnable(h,true) to begin processing audio following this call.
  206. cmRtRC_t cmRtSysCfg( cmRtSysH_t h, const cmRtSysSubSys_t* ss, unsigned rtSubIdx );
  207. cmRtRC_t cmRtSysEndCfg( cmRtSysH_t h );
  208. // Complements cmRtSysInitialize(). In general there is no need to call this function
  209. // since calls to cmRtSysInitialize() and cmRtSysFree() automaticatically call it.
  210. cmRtRC_t cmRtSysFinalize( cmRtSysH_t h );
  211. // Returns true if the audio system has been successfully initialized.
  212. bool cmRtSysIsInitialized( cmRtSysH_t );
  213. // Returns true if the audio system is enabled.
  214. bool cmRtSysIsEnabled( cmRtSysH_t h );
  215. // Enable/disable the audio system. Enabling the starts audio stream
  216. // in/out of the system.
  217. cmRtRC_t cmRtSysEnable( cmRtSysH_t h, bool enableFl );
  218. //
  219. // DSP to Host delivery function
  220. //
  221. // This function is used to pass messages from a DSP process to the HOST it
  222. // is always called from within the real-time thread.
  223. cmRtRC_t cmRtSysDspToHostSegMsg( cmRtSysH_t h, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt);
  224. cmRtRC_t cmRtSysDspToHost( cmRtSysH_t h, const void* msgDataPtr, unsigned msgByteCnt);
  225. //
  226. // Host to DSP delivery functions
  227. //
  228. // Deliver a message from the host application to the DSP process. (host -> DSP);
  229. // The message is formed as a concatenation of the bytes in each of the segments
  230. // pointed to by 'msgDataPtrArrary[segCnt][msgByteCntArray[segCnt]'.
  231. // This is the canonical msg delivery function in so far as the other host->DSP
  232. // msg delivery function are written in terms of this function.
  233. // The first 4 bytes in the first segment must contain the index of the audio sub-system
  234. // which is to receive the message.
  235. cmRtRC_t cmRtSysDeliverSegMsg( cmRtSysH_t h, const void* msgDataPtrArray[], unsigned msgByteCntArray[], unsigned msgSegCnt, unsigned srcNetNodeId );
  236. // Deliver a single message from the host to the DSP system.
  237. cmRtRC_t cmRtSysDeliverMsg( cmRtSysH_t h, const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );
  238. // Deliver a single message from the host to the DSP system.
  239. // Prior to delivery the 'id' is prepended to the message.
  240. cmRtRC_t cmRtSysDeliverIdMsg( cmRtSysH_t h, unsigned rtSubIdx, unsigned id, const void* msgPtr, unsigned msgByteCnt, unsigned srcNetNodeId );
  241. //
  242. // DSP to Host message functions
  243. //
  244. // Is a msg from the DSP waiting to be picked up by the host? (host <- DSP)
  245. // 0 = no msgs are waiting or the msg queue is locked by the DSP process.
  246. // >0 = the size of the buffer required to hold the next msg returned via
  247. // cmRtSysReceiveMsg().
  248. unsigned cmRtSysIsMsgWaiting( cmRtSysH_t h );
  249. // Copy the next available msg sent from the DSP process to the host into the host supplied msg buffer
  250. // pointed to by 'msgBufPtr'. Set 'msgDataPtr' to NULL to receive msg by callback from cmRtSysCfg_t.clientCbFunc.
  251. // Returns kBufTooSmallRtRC if msgDataPtr[msgByteCnt] is too small to hold the msg.
  252. // Returns kNoMsgWaitingRtRC if no messages are waiting for delivery or the msg queue is locked by the DSP process.
  253. // Returns kOkRtRC if a msg was delivered.
  254. // Call cmRtSysIsMsgWaiting() prior to calling this function to get
  255. // the size of the data buffer required to hold the next message.
  256. cmRtRC_t cmRtSysReceiveMsg( cmRtSysH_t h, void* msgDataPtr, unsigned msgByteCnt );
  257. // Fill an audio system status record.
  258. void cmRtSysStatus( cmRtSysH_t h, unsigned rtSubIdx, cmRtSysStatus_t* statusPtr );
  259. // Enable cmRtSysStatus_t notifications to be sent periodically to the host.
  260. // Set rtSubIdx to cmInvalidIdx to enable/disable all sub-systems.
  261. // The notifications occur approximately every cmRtSysCfg_t.meterMs milliseconds.
  262. void cmRtSysStatusNotifyEnable( cmRtSysH_t, unsigned rtSubIdx, bool enableFl );
  263. // Return a pointer the context record associated with a sub-system
  264. cmRtSysCtx_t* cmRtSysContext( cmRtSysH_t h, unsigned rtSubIdx );
  265. // Return the count of audio sub-systems.
  266. // This is the same as the count of cfg recds passed to cmRtSystemInitialize().
  267. unsigned cmRtSysSubSystemCount( cmRtSysH_t h );
  268. // Audio system test and example function.
  269. void cmRtSysTest( cmCtx_t* ctx, int argc, const char* argv[] );
  270. #ifdef __cplusplus
  271. }
  272. #endif
  273. #endif