AddIntServer

add an interrupt server to a system server chain

This function adds a new interrupt server to a given server chain. The node is located on the chain in a priority dependent position. If this is the first server on a particular chain, interrupts will be enabled for that chain.

Each link in the chain will be called in priority order until the chain ends or one of the servers returns with the 68000's Z condition code clear (indicating non-zero). Servers on the chain should return with the Z flag clear if the interrupt was specifically for that server, and no one else. VERTB servers should always return Z set. (Take care with High Level Language servers, the language may not have a mechanism for reliably setting the Z flag on exit).

Servers are called with the following register conventions:

intNum

the Paula interrupt bit number (0 through 14). Processor level seven interrupts (NMI) are encoded as intNum 15. The PORTS, COPER, VERTB, EXTER and NMI interrupts are set up as server chains.

interrupt

pointer to an Interrupt structure. By convention, the LN_NAME of the interrupt structure must point a descriptive string so that other users may identify who currently has control of the interrupt.

Some compilers or assemblers may optimize code in unexpected ways, affecting the conditions codes returned from the function. Watch out for a "MOVEM" instruction (which does not affect the condition codes) turning into "MOVE" (which does).

The graphics library's VBLANK server, and some user code, currently assume that address register A0 will contain a pointer to the custom chips. If you add a server at a priority of 10 or greater, you must compensate for this by providing the expected value ($DFF000).

RemIntServer(), SetIntVector(), "hardware/intbits.i", "exec/interrupts.i"