NAME
    SetICR -- Cause, clear, and sample ICR interrupts.

SYNOPSIS
    oldMask = SetICR( Resource, mask )
    D0                A6        D0

    WORD SetICR( struct Library *, WORD );

FUNCTION
    This function provides a means of reseting, causing, and
    sampling 8520 CIA interrupt control registers.

INPUTS
    mask            A bit mask indicating which interrupts to be
                        effected. If bit 7 is clear the mask
                        indicates interrupts to be reset.  If bit
                        7 is set, the mask indicates interrupts to
                        be caused. Bit positions are identical to
                        those in 8520 ICR.

RESULTS
    oldMask         The previous interrupt register status before
                        making the requested changes.  To sample
                        current status without making changes,
                        call the function with a null parameter.

EXAMPLES
    Get the interrupt mask:
        mask = SetICR(0)
    Clear serial port interrupt:
        SetICR(0x08)

NOTE
    The CIA resources are special in that there is more than one
    of them in the system. Because of this, the C language stubs
    in amiga.lib for the CIA resources require an extra parameter
    to specify which CIA resource to use. The synopsys for the
    amiga.lib stubs is as follows:

    oldMask = SetICR( Resource, mask )
    D0                A6        D0

    WORD SetICR( struct Library *, WORD );

    ***WARNING***

    Never read the contents of the CIA interrupt control registers
    directly.  Reading the contents of one of the CIA interrupt
    control registers clears the register.  This can result in
    interrupts being missed by critical operating system code, and
    other applications.

EXCEPTIONS
    Setting an interrupt bit for an enabled interrupt will cause
    an immediate interrupt.

SEE ALSO
    cia.resource/AbleICR()