CC2541之回调函数代码解析

转自：香瓜博客

回调函数，解析代码：一 、定义一个 “ 成员为函数指针 ” 的结构体1 ）定义一个函数指针/*** Central Event Callback Function*/typedef void (*pfnGapCentralRoleEventCB_t)(gapCentralRoleEvent_t *pEvent //!< Pointer to event structure.);它的参数是一个 gapCentralRoleEvent_t 类型的消息指针 *pEvent 。其中， gapCentralRoleEvent_t 的类型如下/*** Central Event Structure*/typedef union{gapEventHdr_t gap; //!< GAP_MSG_EVENT and status.gapDeviceInitDoneEvent_t initDone; //!< GAP initialization done.gapDeviceInfoEvent_t deviceInfo; //!< Discovery device information event structure.gapDevDiscEvent_t discCmpl; //!< Discovery complete event structure.gapEstLinkReqEvent_t linkCmpl; //!< Link complete event structure.gapLinkUpdateEvent_t linkUpdate; //!< Link update event structure.gapTerminateLinkEvent_t linkTerminate; //!< Link terminated event structure.} gapCentralRoleEvent_t;2 ）定义一个结构体/*** Central Callback Structure*/typedef struct{pfnGapCentralRoleRssiCB_t rssiCB; //!< RSSI callback.pfnGapCentralRoleEventCB_t eventCB; //!< Event callback.} gapCentralRoleCB_t;gapCentralRoleCB_t 结构体有两个成员，一个是 pfnGapCentralRoleRssiCB_t 类型的成员，一个是 pfnGapCentralRoleEventCB_t 类型的成员。二 、写一个回调函数，并完成注册1 ）定义一个函数 simpleBLECentralEventCB/********************************************************************** @fn simpleBLECentralEventCB** @brief Central event callback function.** @param pEvent - pointer to event structure** @return none*/static void simpleBLECentralEventCB( gapCentralRoleEvent_t *pEvent ){switch ( pEvent->gap.opcode ){case GAP_DEVICE_INIT_DONE_EVENT:{LCD_WRITE_STRING( "BLE Central", HAL_LCD_LINE_1 );LCD_WRITE_STRING( bdAddr2Str( pEvent->initDone.devAddr ), HAL_LCD_LINE_2 );}break;case GAP_DEVICE_INFO_EVENT:{// if filtering device discovery results based on service UUIDif ( DEFAULT_DEV_DISC_BY_SVC_UUID == TRUE ){if ( simpleBLEFindSvcUuid( SIMPLEPROFILE_SERV_UUID,pEvent->deviceInfo.pEvtData,pEvent->deviceInfo.dataLen ) ){simpleBLEAddDeviceInfo( pEvent->deviceInfo.addr, pEvent->deviceInfo.addrType );}}}break;case GAP_DEVICE_DISCOVERY_EVENT:{// discovery completesimpleBLEScanning = FALSE;// if not filtering device discovery results based on service UUIDif ( DEFAULT_DEV_DISC_BY_SVC_UUID == FALSE ){// Copy resultssimpleBLEScanRes = pEvent->discCmpl.numDevs;osal_memcpy( simpleBLEDevList, pEvent->discCmpl.pDevList,(sizeof( gapDevRec_t ) * pEvent->discCmpl.numDevs) );}LCD_WRITE_STRING_VALUE( "Devices Found", simpleBLEScanRes,10, HAL_LCD_LINE_1 );if ( simpleBLEScanRes > 0 ){LCD_WRITE_STRING( "<- To Select", HAL_LCD_LINE_2 );}// initialize scan index to last devicesimpleBLEScanIdx = simpleBLEScanRes;}break;case GAP_LINK_ESTABLISHED_EVENT:{if ( pEvent->gap.hdr.status == SUCCESS ){simpleBLEState = BLE_STATE_CONNECTED;simpleBLEConnHandle = pEvent->linkCmpl.connectionHandle;simpleBLEProcedureInProgress = TRUE;// If service discovery not performed initiate service discoveryif ( simpleBLECharHdl == 0 ){osal_start_timerEx( simpleBLETaskId, START_DISCOVERY_EVT, DEFAULT_SVC_DISCOVERY_DELAY );}LCD_WRITE_STRING( "Connected", HAL_LCD_LINE_1 );LCD_WRITE_STRING( bdAddr2Str( pEvent->linkCmpl.devAddr ), HAL_LCD_LINE_2 );}else{simpleBLEState = BLE_STATE_IDLE;simpleBLEConnHandle = GAP_CONNHANDLE_INIT;simpleBLERssi = FALSE;simpleBLEDiscState = BLE_DISC_STATE_IDLE;LCD_WRITE_STRING( "Connect Failed", HAL_LCD_LINE_1 );LCD_WRITE_STRING_VALUE( "Reason:", pEvent->gap.hdr.status, 10, HAL_LCD_LINE_2 );}}break;case GAP_LINK_TERMINATED_EVENT:{simpleBLEState = BLE_STATE_IDLE;simpleBLEConnHandle = GAP_CONNHANDLE_INIT;simpleBLERssi = FALSE;simpleBLEDiscState = BLE_DISC_STATE_IDLE;simpleBLECharHdl = 0;simpleBLEProcedureInProgress = FALSE;LCD_WRITE_STRING( "Disconnected", HAL_LCD_LINE_1 );LCD_WRITE_STRING_VALUE( "Reason:", pEvent->linkTerminate.reason,10, HAL_LCD_LINE_2 );}break;case GAP_LINK_PARAM_UPDATE_EVENT:{LCD_WRITE_STRING( "Param Update", HAL_LCD_LINE_1 );}break;default:break;}}2 ）声明函数static void simpleBLECentralEventCB( gapCentralRoleEvent_t *pEvent );3 ）使 simpleBLECentralEventCB 成为回调函数// GAP Role Callbacksstatic const gapCentralRoleCB_t simpleBLERoleCB ={simpleBLECentralRssiCB, // RSSI callbacksimpleBLECentralEventCB // Event callback};三 、调用回调函数1 ）定义一个新的函数指针变量 pGapCentralRoleCB （ central.c ）// App callbacksstatic gapCentralRoleCB_t *pGapCentralRoleCB;2 ）将 pGapCentralRoleCB 指向回调函数 simpleBLECentralEventCB ，也就是注册回调函数。/*** @brief Start the device in Central role. This function is typically* called once during system startup.** Public function defined in central.h.*/bStatus_t GAPCentralRole_StartDevice( gapCentralRoleCB_t *pAppCallbacks ){if ( pAppCallbacks ){pGapCentralRoleCB = pAppCallbacks;}return GAP_DeviceInit( gapCentralRoleTaskId, GAP_PROFILE_CENTRAL,gapCentralRoleMaxScanRes, gapCentralRoleIRK,gapCentralRoleSRK, &gapCentralRoleSignCounter );}3 ）调用回调函数// Pass event to appif ( pGapCentralRoleCB && pGapCentralRoleCB->eventCB ){pGapCentralRoleCB->eventCB( (gapCentralRoleEvent_t *) pMsg );}}注：实际上此时 simpleBLECentralEventCB 在第二步结束时，即可直接通过操作结构体来调用这个回调函数了。但是之所以要将结构体中的 simpleBLECentralEventCB 函数首地址再传给 simpleBLECentralEventCB （即第三点的 1 、 2 两个步骤），我认为是出于底层的 profiles——central 分层的考虑。