F$Icpt
From NitrOS-9
| Intercept | Sets a signal intercept trap |
| OS9 F$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
