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From: carolyn@cbmvax.commodore.com (Carolyn Scheppner - CATS)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Question on AbortIO() and WaitIO()
Message-ID: <21757@cbmvax.commodore.com>
Date: 20 May 91 23:14:26 GMT
References: <28630@uflorida.cis.ufl.EDU>
Reply-To: carolyn@cbmvax.commodore.com (Carolyn Scheppner - CATS)
Organization: Commodore, West Chester, PA
Lines: 62

In article <28630@uflorida.cis.ufl.EDU> leh@otter.cis.ufl.edu (Les Hill) writes:
>I have run into a situation which is not clearly documented (to me anyways) in the
>RKM's (v1.2 ?).  Below I have included the relevant fragments of code:
>...
>   struct MsgPort *read_port, *write_port;
>   struct IOExtSer *read_req, *write_req;
>...
>   BYTE dev_error;
>   struct Message *read_msg;
>...
>   /* 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), the CMD_READ request is then aborted and
>a WaitIO() follows as recommended in the RKMs; the WaitIO() returns a -2
>(aborted request.)
>
>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?
>Additionally, do I need the GetMsg()?

   NAME
        WaitIO -- wait for completion of an I/O request

   SYNOPSIS
        error = WaitIO(iORequest)
        D0             A1

        BYTE WaitIO(struct IORequest *);

   FUNCTION
        This function waits for the specified I/O request to complete, then
        removes it from the replyport.  If the I/O has already completed,
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        this function will return immediately.


If you KNOW there is an outstanding request, I believe the best
action is:

if(!CheckIO(ioreq))	AbortIO(ioreq);
WaitIO(ioreq);

Then regardless of whether the request had already completed, it
any signal it generated will be cleared and it will be removed
from the port.

-- 
==========================================================================
 Carolyn Scheppner -- Tech. Mgr. CATS - Commodore Amiga Technical Support
 PHONE 215-431-9180 {uunet,rutgers}!cbmvax!carolyn  carolyn@commodore.com

 Spice up old code with a dazzling array of pointers to void functions.
==========================================================================