NAME
AddIntServer -- add an interrupt server to a system server chain
SYNOPSIS
AddIntServer(intNum, interrupt)
D0-0:4 A1
void AddIntServer(ULONG, struct Interrupt *);
FUNCTION
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:
D0 - scratch
D1 - scratch
A0 - scratch
A1 - server is_Data pointer (scratch)
A5 - jump vector register (scratch)
A6 - scratch
all other registers must be preserved
INPUTS
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.
WARNING
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).
BUGS
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).
SEE ALSO
RemIntServer, SetIntVector, hardware/intbits.i,exec/interrupts.i