Commodore Amiga A500 Technical Reference Manual page 138

Each jintnum may be individually enabled or disabled (this is in addi-
tion to the control of setting the interrupt handler t o NULI.). If the
interrupt is disabled then requests that are received will not generate
interrupts. These requests may be detected via SetJanusRequest.
If newvalue is
0
then the interrupt is disabled. If
it
is
1
then the inter-
rupt is enabled.
All
other values are reserved.
This routine will generate an interrupt if it an interrupt is enabled
that has a pending request. This does not currently happen until the
next hardware interrupt occurs.
oldRequest = SetJanusRequest( jintnum, newvalue
)
DO D1
This routine sets or clears an interrupt request forjintnum. If new-
value is zero then the request is cleared. If newvalue is one then the
request is set. In either case the old value of the request is returned.
Setting a request will generate an interrupt
(if
it is enabled). This
does not currently happen.
SendJanuslnt( jintnum
)
DO
This call is useful for "system" requests
-
e.g. those requests not di-
rectly defined by the hardware. The call marks the request in the sys-
tem interrupt area and then posts a hardware interrupt to the pc.
CheckJanuslnt( jintnum
)
DO
This call returns the status byte from the interrupt area. It can be
used to tell if the pc has noticed the interrupt yet. A value of JNOINT
($m
means no interrupt is pending (which probably means that the
pc has already processed it). JSENDINT ($70 means that the inter-
rupt is pending. Anything else should be treated with suspicion.
ptr = AllocJanusMem( size, type
)
DO D1
This routine allocates memory from the parameter or buffer mem-
ory free pools, and returns a
68000
addressable pointer to the
memory. It allocates "size" bytes, or returns NULL if there was not
enough memory.
The type field is used to determine which pool of memory is desired.
It
should be either MEMF-PARAMETER or MEMF-BUFFER. In addi-
tion, you may specify what sort of memory access the pointer should
refer to. The four choices are MEM-BYTEACCESS, MEM-WORD-