Implementation Notes
The following implementation notes are useful when programming or modifying the API.
Big and Little Endian Functions
The following API functions have separate implementations for little endian architectures, and are used when the CIGI_LITTLE_ENDIAN
preprocessor definition is defined. For more information on the CIGI_LITTLE_ENDIAN preprocessor definition, please refer to the topic on
preprocessor definitions.
Note that the little endian function versions are named the same as the big endian functions, but with the LE suffix, as
shown in the following table. The little endian functions are not called directly, but are defined in the cigi_api.h header file to take the
place of calls to the big endian functions. These include the CigiSyncFrameCounter, CigiProcessIncomingMsgBuffer,
CigiGetFirstPacket, and all of the CigiAddPacketXXX methods.
Table : Big and Little Endian Function Versions
| Big Endian Version |
Little Endian Version |
| CigiSyncFrameCounter |
CigiSyncFrameCounterLE |
| CigiProcessIncomingMsgBuffer |
CigiProcessIncomingMsgBufferLE |
| CigiGetFirstPacket |
CigiGetFirstPacketLE |
| CigiAddPacketIGCtrl |
CigiAddPacketIGCtrlLE |
| CigiAddPacketEntityCtrl |
CigiAddPacketEntityCtrlLE |
| CigiAddPacketComponentCtrl |
CigiAddPacketComponentCtrlLE |
| CigiAddPacketArtPartCtrl |
CigiAddPacketArtPartCtrlLE |
| CigiAddPacketRateCtrl |
CigiAddPacketRateCtrlLE |
| CigiAddPacketEnvCtrl |
CigiAddPacketEnvCtrlLE |
| CigiAddPacketWeatherCtrl |
CigiAddPacketWeatherCtrlLE |
| CigiAddPacketViewCtrl |
CigiAddPacketViewCtrlLE |
| CigiAddPacketSensorCtrl |
CigiAddPacketSensorCtrlLE |
| CigiAddPacketTrajectoryDef |
CigiAddPacketTrajectoryDefLE |
| CigiAddPacketEffectDef |
CigiAddPacketEffectDefLE |
| CigiAddPacketViewDef |
CigiAddPacketViewDefLE |
| CigiAddPacketCollisionDetDef |
CigiAddPacketCollisionDetDefLE |
| CigiAddPacketVolumeCollDetDef |
CigiAddPacketVolumeCollDetDefLE |
| CigiAddPacketHatReq |
CigiAddPacketHatReqLE |
| CigiAddPacketLosOccultReq |
CigiAddPacketLosOccultReqLE |
| CigiAddPacketLosRangeReq |
CigiAddPacketLosRangeReqLE |
| CigiAddPacketHotReq |
CigiAddPacketHotReqLE |
| CigiAddPacketSof |
CigiAddPacketSofLE |
| CigiAddPacketHatResp |
CigiAddPacketHatRespLE |
| CigiAddPacketLosResp |
CigiAddPacketLosRespLE |
| CigiAddPacketColResp |
CigiAddPacketColRespLE |
| CigiAddPacketSensorResp |
CigiAddPacketSensorRespLE |
| CigiAddPacketHotResp |
CigiAddPacketHotRespLE |
| CigiAddPacketVolumeCollDetResp |
CigiAddPacketVolumeCollDetRespLE |
| CigiAddPacketIGResponseMessage |
CigiAddPacketIGResponseMessageLE |
|
Memory Allocation
In general, dynamic memory allocation, using the malloc() function, should be avoided during the communication between the
host and IG. Thus the API allocates the memory needed to manage sessions during the CigiInit() initialization function, and
the memory needed by a particular session is allocated when the session is created, through a call to the CigiCreateSession()
function.
Multiple Threaded Applications
The API is not thread-safe, and thus the responsibility is on the user of the API to access it in a thread-safe way. Notice also, the use of
static variables in the function definitions, meaning that functions should not entered and completed one at a time.
Static variables have been used in functions, so that they would not be created on the stack each time a function is called, making the API
faster, but harder to synchronize from multiple threads. The API also uses static memory, which is global to the API in all threads.
Sessions
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