DOS/32 Advanced DOS Extender - Programmer's Reference

2.46 - DPMI function 0901h - Get and Enable Virtual Interrupt State

Enables the virtual interrupt flag and returns the previous state of the virtual interrupt flag.


In: AX = 0901h
Out: CF clear
Virtual interrupts enabled
AL = 0 if virtual interrupts were previously disabled
AL = 1 if virtual interrupts were previously enabled


a) AH is not changed by this function. Therefore, the previous state can be restored by simply executing another INT 31h. See DPMI function 0900h.

b) A client that does not need to know the prior interrupt state can execute the STI instruction rather than calling this function. The instruction may be trapped by the host and should be assumed to be very slow.


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