Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!decwrl!ucbvax!research2.computer-science.manchester.ac.uk!aek
From: aek@research2.computer-science.manchester.ac.uk (Alan Knowles)
Newsgroups: comp.sys.transputer
Subject: Re:Semantics of In and Out instructions for memory channels?
Message-ID: <9002261503.AA12187@prg.ox.ac.uk>
Date: 26 Feb 90 15:03:55 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 17

Dan McCabe asks:

>       Does anyone out in Netland know details about the semantics of the
>       In and Out instructions when a memory channel is specified?
>       .......
>       Is the channel a linked list of waiting processes?  It seems to me
>       that this would have to be the case, since several processes may
>       Out to the same channel before another process does an In.
WRONG.  Only one pair of processes may access a channel: one sending and one
receiving. The workspace pointer of the first process to "arrive" is put in
the channel word and message transfer takes place on the "arrival" of the
second process. It is assumed that rigourous checking has taken place. The
direction and size of message transfer is performed according to the implied
direction of the second "arrival". Only the workspace pointer of the first
"arrival is kept".

Alan Knowles