Software Interrupt Intrinsics

Three intrinsics are specific to software interrupts: FCONTROL with a controlcode of 48, FINTSTATE, and FINTEXIT.

FCONTROL with a controlcode of 48 arms software interrupts for a particular file. It is also used by the application to tell MPE/iX the address of the application's interrupt handler.

	NOTE: The param parameter of FCONTROL is used to pass the interrupt handler's procedure label (plabel). Native Mode plabels are 32 bits long, while Compatibility Mode plabels are 16 bits. Therefore, the interrupt handler and the FCONTROL call to it must be compiled in the same mode. Arming software interrupts in cross-mode programming can be unpredictable, and you should avoid this whenever possible.

FINTSTATE is used by the application to enable or disable software interrupts for all files with interrupts armed by this process. FINTSTATE also returns a code which shows the status of the interrupts prior to the time it was invoked; it returns a 0 if software interrupts were disabled and a 1 if software interrupts were enabled.

FINTEXIT is used to return from the interrupt handler and leave software interrupts enabled or disabled.

The following section explains how to set up and use software interrupts.