AddTimerInt

adds an interrupt that is executed at regular intervals. (V40)

Calling this routine causes the system to allocate a CIA timer and set up 'intRoutine' to service any interrupts caused by the timer. Although the timer is allocated it is neither running, nor enabled. StartIntTimer() must be called to establish the time interval and start the timer.

The routine is called from within an interrupt, so normal restrictions apply. The routine must preserve the following registers: A2, A3, A4, A7, D2-D7. Other registers are scratch, except for D0, which MUST BE SET TO 0 upon exit. On entry to the routine, A1 holds 'intData' and A5 holds 'intRoutine'.

Only a single CIA timer will be allocated by this routine. So this routine may only be called once without an intervening call to RemTimerInt().

The CIA timer used by this routine is not guaranteed to always be the same. This routine utilizes the CIA resource and uses an unallocated CIA timer.

If your program is to exit without reboot, you MUST match all calls to this function with calls to RemTimerInt() before exiting.

Even if you only use the function once in your program; checking the return value will make your program more tolerant for mulititasking on the Amiga computer platforms.

intRoutine

the routine to invoke upon timer interrupts. This routine should be as short as possible to minimize its effect on overall system performance.

intData

data passed to the routine in register A1. If more than one long word of data is required this should be a pointer to a structure that contains the required data.

intHandle

a handle used to manipulate the interrupt, or NULL if it was not possible to attach the routine.

RemTimerInt(), StopTimerInt(), StartTimerInt()