Inside Macintosh: Networking With Open Transport / Part 2 - Open Transport Reference

Appendix C - Special Functions

Functions Callable at Hardware Interrupt Time

Table C-1 lists client functions that you can safely call at hardware interrupt time (from completion routines, VBL tasks, Time Manager tasks, and others), and specifies whether you must call the OTEnterInterrupt function before calling the function.

That these functions are safe to call, however, does not imply that they interact predictably with non-interrupt code. For instance, while it is safe to call the OTAddFirst function at interrupt time, the actual add operation is not atomic, so calling it at interrupt time could adversely affect non-interrupt code processing the same list. Thus, for each function listed in the table, information is also provided as to whether the operation is atomic.

Table C-1  Functions callable at hardware interrupt time, all ISAs

Function	Needs OTEnterInterrupt?	Atomic
OTAcquireLock	no	yes
OTAddFirst	no	no
OTAddLast	no	no
OTAllocMem	no	n/a
OTAtomicAdd16	no	yes
OTAtomicAdd32	no	yes
OTAtomicAdd8	no	yes
OTAtomicClearBit	no	yes
OTAtomicSetBit	no	yes
OTAtomicTestBit	no	yes
OTCancelSystemTask	no	n/a
OTCanLoadLibraries	yes	no
OTCanMakeSyncCall	yes	no
OTClearLock	no	yes
OTCompareAndSwap16	no	yes
OTCompareAndSwap32	no	yes
OTCompareAndSwap8	no	yes
OTCompareAndSwapPtr	no	yes
OTCreatePortRef	no	n/a
OTDequeue	no	yes
OTElapsedMicroseconds	no	n/a
OTElapsedMilliseconds	no	n/a
OTEnqueue	no	yes
OTFindAndRemoveLink	no	no
OTFindLink	no	no
OTFreeMem	no	n/a
OTGetBusTypeFromPortRef	no	n/a
OTGetClockTimeInSecs	no	n/a
OTGetDeviceTypeFromPortRef	no	n/a
OTGetFirst	no	no
OTGetIndexedLink	no	no
OTGetLast	no	no
OTGetSlotFromPortRef	no	n/a
OTGetTimeStamp	no	n/a
OTIsAtInterruptLevel	no	n/a
OTIsInList	no	no
OTLIFODequeue	no	yes
OTLIFOEnqueue	no	yes
OTLIFOStealAndReverseList	no	yes
OTLIFOStealList	no	yes
OTMemcmp	no	n/a
OTMemcpy	no	n/a
OTMemmove	no	n/a
OTMemset	no	n/a
OTMemzero	no	n/a
OTRemoveFirst	no	no
OTRemoveLast	noc	no
OTRemoveLink	no	no
OTReverseList	no	no
OTScheduleDeferredTask	yes	n/a
OTScheduleInterruptTask	no	n/a
OTScheduleSystemTask	yes	n/a
OTSetBusTypeInPortRef	no	n/a
OTSetDeviceTypeInPortRef	no	n/a
OTStrCat	no	n/a
OTStrCopy	no	n/a
OTStrEqual	no	n/a
OTStrLength	no	n/a
OTSubtractTimeStamps	no	n/a
OTTimeStampInMicroseconds	no	n/a
OTTimeStampInMilliseconds	no	n/a
OTWhoAmI	no	n/a