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From: peirce@outpost.UUCP (Michael Peirce)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Can I/O Completion routine call 'GetRequest'??
Message-ID: <0B010004.nn2ddd@outpost.UUCP>
Date: 20 Apr 91 17:27:25 GMT
Reply-To: peirce@outpost.UUCP
Organization: Peirce Software
Lines: 39
X-Mailer: uAccess - Mac Release: 1.0.3


In article <63618@bbn.BBN.COM>, rmitchel@bbn.com (Rob Mitchell) writes:
> 
> 
>     I've created a list of 20 parameter blocks and queued them into a 
>     pseudo "free" list (at the start of my program).  Each has a "state"
>     of FREE.  I call ATP's 'GetRequest' asynchronously once using a globally 
>     created param block (should it really be a global or one of the "free" 
>     ones?).
> 
>     When Mac receives a TReq, my I/O Completion routine assigns reg. A0
>     (which contains address of current param block) to local variable and
>     set param's "state" to INCOMING.  
> 
>     What I need to do now is queue another 'GetRequest' from my I/O
>     Completion routine.  Can I call I use a different "free" element
>     and make the 'GetRequest' call from my I/O Completion routine?
>     I'm not allocating/moving any memory, right?  GetRequest should
>     just assign a bunch of pointers, right?  It probably doesn't move
> 	or allocate any memory, right??
> 
>     How else can I have at least one 'GetRequest' always outstanding
>     at *any* given time?????
> 
>     Thanks in advance!!!!

Sounds like you have the right idea.  Calling PGetRequest from a completion
routine is fine and a common approach found in many programs.  And
it's the only way to implement programs that live only at interrupt
level.  Just be doubly sure that that your parameter blocks are really
free when you reuse them!

Good luck with your project.


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