https://invisible-island.net/xterm/xtoolkit/
XtAddInput, XtAddTimeOut, XtAddWorkProc - register input, timeout, and
workprocs
#include <X11/Intrinsic.h>
XtInputId XtAddInput(int source, XtPointer condition, XtInputCallback-
Proc proc, XtPointer client_data);
XtIntervalId XtAddTimeOut(unsigned long interval, XtTimerCallbackProc
proc, XtPointer client_data);
XtWorkProcId XtAddWorkProc(XtWorkProc proc, XtPointer client_data);
client_data
Specifies the argument that is to be passed to the specified
procedure when input is available
condition Specifies the mask that indicates a read, write, or exception
condition or some operating system dependent condition.
proc Specifies the procedure that is to be called when input is
available.
source Specifies the source file descriptor on a UNIX-based system
or other operating system dependent device specification.
XtAddInput has been replaced by XtAppAddInput.
XtAddTimeOut has been replaced by XtAppAddTimeOut.
XtAddWorkProc has been replaced by XtAppAddWorkProc.
XtAppAddInput(3), XtAppAddTimeOut(3), XtAppAddWorkProc(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.3.1 XtAddInput(3)