F$Icpt modified by Lothan

Lothan — Fri, 27 Jun 2014 23:20:53 -0000

Intercept
Sets a signal intercept trap

OS9 F$Icpt 103F 09

Entry Conditions

X address of the intercept routine

U starting address of the routine’s memory area

Exit Conditions

Signals sent to the process cause the intercept routine to be called instead of the process being killed.

Additional Information

Intercept tells NitrOS-9 to set a signal intercept trap. Then, whenever the process receives a signal, NitrOS-9 executes the process’s intercept routing.
Store the address of the signal handler routine in Register X and the base address of the routine’s storage area in Register U.
Once the signal trap is set, NitrOS-9 can execute the intercept routine at any time because a signal can occur at any time.
Terminate the intercept routine with an RTI instruction.
If a process has not used the Intercept system call to set a signal trap, the process terminates if it receives a signal.
This is the order in which F$Icpt operates:
When the process receives a signal, NitrOS-9 sets Registers U and B as follows:

U starting address of the intercept routine’s memory area

B signal code (process’s termination status)

Note: The value of Register DP cannot be the same as it was when the Intercept call was made.

After setting the registers, NitrOS-9 transfers execution to the intercept routine.

krnp2

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