Dave Rahardja

Possible to atomically disable interrupts during initial ISR handling?

Discussion created by Dave Rahardja on Feb 24, 2007
Latest reply on Mar 9, 2007 by Dave Rahardja
I've seen the following code at the entry point of several 52xx ISRs:


_isr:
    MOVE.W #0x2700,SR ; Disable interrupts
    ...


My question is: is it possible for another interrupt to "sneak in" right after the exception frame is pushed on the stack, but just before that first instruction is executed?

The V2 Core documentation says that exception handling terminates when the first instruction in the interrupt handler is FETCHED, so I'm assuming that the first instruction will ALWAYS be executed before another exception can be handled. I just want to make sure this is so.

Message Edited by Dave Rahardja on 2007-02-2410:22 PM

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