listening for input with CLX

[janson@ATHENA.MIT.EDU]

hello:

does someone know how to perform the equivalent of a listen on the
file descriptor associated with the input stream for a given display?

i noticed that the r4 CLX code has support for this, but i can find neither
neither the equivalent R3 CLX functions, nor the base functions which the R4
code used.

the salient function appears to be:

(defun fd-char-avail-p (fd)
  (multiple-value-bind (available-p errcode)
      (comp::.primcall-sargs 'sys::filesys excl::fs-char-avail fd)
    (if* errcode
       then t
       else available-p)))

i am using allegro cl: "3.1.beta.28 [DEC 3100] (8/3;8/7/89)"

thanks.
james anderson.