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

Chapter 23 - Programming With Open Transport Reference / Functions

Entering and Leaving Hardware Interrupt Time /

OTEnterInterrupt

Notifies Open Transport that you are about to call an Open Transport function from a hardware interrupt.

C INTERFACE

void OTEnterInterrupt(void)

C++ INTERFACE

None. C++ applications use the C interface to this function.

DISCUSSION

The OTEnterInterrupt function informs Open Transport it is at hardware interrupt time. This allows Open Transport to schedule network activity more intelligently. You must use this function before calling many of the Open Transport functions from hardware interrupt time, for example, from a VBL or Time Manager task, or from a File Manager or Device Manager I/O completion routine. There are only a limited number of Open Transport functions that you can actually call at hardware interrupt time; these are listed in Appendix C.

You must call the OTLeaveInterrupt function before you leave interrupt time.

Note

The OTEnterInterrupt function was provided to enable callers of the OTScheduleDeferredTask function a means to let Open Transport know that the scheduling was occurring at interrupt time. With the addition of the OTScheduleInterruptTask function (which calls OTEnterInterrupt internally), it is no longer necessary to call the OTEnterInterrupt function. There are cases, however, when it might be advisable to call the OTEnterInterrupt and OTScheduleDeferredTask functions in sequence; for example, when you want to schedule two deferred tasks consecutively, or when you are calling a common function which uses OTScheduleDeferredTask and which is sometimes called at interrupt time and sometimes not.

SPECIAL CONSIDERATIONS

If you are running 680x0-based code, you must be sure that your A5 world is set correctly before making this call (that is, that it has the same value it had when you called the InitOpenTransport or the InitOpenTransportUtilities function).

SEE ALSO

The OTLeaveInterrupt function.

"Hardware Interrupt Level".