Article View: comp.sys.transputer
Article #685Re: Protocol query
From: Jan Vorbrueggen
Date: Mon, 07 Sep 1992 14:28
Date: Mon, 07 Sep 1992 14:28
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1798 bytes
What you're really trying to do is extracting a part of memory with nonunit stride. (Unit stride is of course handled just by using assignment in occam and translated into the MOVE instruction.) The T800 and followon (T425, T400, T805, T801) have MOVE2D exactly for this purpose. Unfortunately, the compiler's builtin function has a braindamaged interface (IMHO) requiring massive RETYPES, as well as some code generation bugs (if certain arguments aren't constant or VALs, space is allocated for their computation, but the computation is never done :)). So I defined my own routine(s) for the purpose. It is very efficient: For instance, if you're doing, say, a 2D FFT, for the column part it is better to extract each column into a 1D array, perform the FFT on it, and reinsert it with MOVE2D. This works because you save massively on address computations, need only a 1D FFT that is unaware it is working on a 2D array, and you can PLACE the temporary array into the WORKSPACE. So the solution is to extract your data from your 2D array into a buffer using MOVE2D, send that, and scatter it at the receiving end via MOVE2D, if required. Jan Vorbrueggen, Inst. f. Neuroinformatik, RuhrUniversitaet Bochum, FRG jan@neuroinformatik.ruhrunibochum.de
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Newsgroups: comp.sys.transputer Path: arc1-ca.pugleaf.net!sparky!uunet!haven.umd.edu!darwin.sura.net!Sirius.dfn.de!rz.ruhr-uni-bochum.de!jan From: jan@pallas.neuroinformatik.ruhr-uni-bochum.de (Jan Vorbrueggen) Subject: Re: Protocol query Message-ID: <JAN.92Sep7142820@pallas.neuroinformatik.ruhr-uni-bochum.de> In-reply-to: MJP@starlink.roe.ac.uk's message of 4 Sep 92 12:51:00 GMT Organization: Inst. f. Neuroinformatik, Ruhr-Universitaet Bochum, FRG References: <7271.9209041250@prg.ox.ac.uk> Date: 7 Sep 92 14:28:20 Lines: 22