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From: brian@ut-sally.UUCP (Brian H. Powell)
Newsgroups: net.micro.mac
Subject: Event queue questions
Message-ID: <2010@ut-sally.UUCP>
Date: Sun, 26-May-85 16:03:42 EDT
Article-I.D.: ut-sally.2010
Posted: Sun May 26 16:03:42 1985
Date-Received: Mon, 27-May-85 07:27:55 EDT
Distribution: net
Organization: U. Texas CS Dept., Austin, Texas
Lines: 26


     I am considering writing a desk accessory that will have to post items
on the event queue.  I suspect there will be a problem in filling up the
event queue.  There seems to be no means of finding out if the event queue
is full.  (PostEvent just discards the oldest event and posts the new event.
This means there is a good chance events will be lost.)
     The only solution I envision is for the desk accessory to slow down and
only post events when there is room.  So how do I find the size of the queue?
The only solution to this seems to be to traverse the queue, counting the
events.  (Is there a better way?)
     In Pascal, there is a "function GetEvQHdr : QHdrPtr; [Pascal only]"
which returns a pointer to the event queue.  I am using assembly.
Inside Mac says:
  "To access the contents of the event queue from assembly language, you can
use offsets from the address of the global variable EventQueue."
Umm, offsets?  Apparently this isn't just a pointer to the event queue.  (or
is it?)  IM doesn't say what kind of structure it is.  Can anybody elucidate?


Brian H. Powell      brian@ut-sally.{ARPA,UUCP}

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