[Main]
Name=DUMMY_HANDLER
Type=Function
Subtype=tigcc.a
Header Files=intr.h
Definition=INT_HANDLER DUMMY_HANDLER;
Real Definition=#define DUMMY_HANDLER ((INT_HANDLER) (&__dummy_handler__))

[Description]
A dummy interrupt handler doing nothing.

[Explanation]
DUMMY_HANDLER is an interrupt handler of type <A HREF="$$LINK(intr.h/INT_HANDLER)">INT_HANDLER</A>
which consists only of <CODE>'rte'</CODE>. The purpose of this handler is
to redirect an interrupt vector to "nothing", in cases when disabling interrupts is not
possible. For example, you can not disable auto-int 1 in grayscale programs, because grayscale
support is based on it. Grayscale support installs its own auto-int 1 handler, which executes
the previously installed handler at the end. Suppose that you don't want it to call the default auto-int 1
handler, which trashes the status line by displaying keyboard status indicators. You can
redirect auto-int 1 to the dummy handler <I>before</I> enabling grayscale, so
after the grayscale interrupt, the dummy handler (i.e. nothing) will be called instead of the
default auto-int 1 handler:
<PRE>INT_HANDLER save_int_1;
...
save_int_1 = GetIntVec (AUTO_INT_1);
SetIntVec (AUTO_INT_1, DUMMY_HANDLER);   // <I>redirect auto-int 1 to "nothing"</I>
// <I>enable grayscale</I>
// <I>do whatever you want in grayscale</I>
// <I>disable grayscale</I>
SetIntVec (AUTO_INT_1, save_int_1);
</PRE>
