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From: valentin@public.BTR.COM (Valentin Pepelea)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Question on AbortIO() and WaitIO()
Message-ID: <2865@public.BTR.COM>
Date: 23 May 91 07:45:32 GMT
References: <28630@uflorida.cis.ufl.EDU>
Organization: BTR Communications, Mtn. View, CA
Lines: 47

In article <28630@uflorida.cis.ufl.EDU> leh@otter.cis.ufl.edu (Les Hill)
writes:
>
>   /* Clean up */
>   if (!CheckIO(read_req)) {
>      AbortIO(read_req);
>      if (dev_error = WaitIO(read_req)) {
>         printf("Error waiting for aborted read -- %d\n", dev_error);
>         goto cleanup_8;
>      }
>      read_msg = GetMsg(read_port); // not necessary?
>   }
>...
>
>The situation is this: a CMD_READ request *should* be queued at the device
>(the CheckIO() should confirm this),

Not really. The IO request could have been processed between the time ChechIO
was called and AbortIO is about to be.

>The question that comes to mind is: does WaitIO() dequeue the reply at
>read_port (read_port is the reply port for read_req) regardless of the error?

Yes, WaitIO() makes sure the message is dequeued.

>Additionally, do I need the GetMsg()?

No you don't. This is a bug. The line:

>      read_msg = GetMsg(read_port); // not necessary?

should have read	> else read_msg = GetMsg(read_port)

However, you should note the the best method to perform the given operation
is simply:

	AbortIO(IORequest);
	WaitIO(IORequest);

If the IORequest had already completed, then AbortIO does nothing.

Valentin
-- 
"An operating system without virtual memory      Name:      Valentin Pepelea
 is an operating system without virtue."         Phone:     (408) 985-1700
                                                 Usenet:    mips!btr!valentin
                     - Ancient Inca Proverb      Internet:  valentin@btr.com