Xref: utzoo comp.lang.c++:2169 comp.lang.c:14460 comp.lang.forth:706 comp.lang.fortran:1573 comp.lang.misc:2255 comp.arch:7412 Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!chiba!khb From: khb%chiba@Sun.COM (Keith Bierman - Sun Tactical Engineering) Newsgroups: comp.lang.c++,comp.lang.c,comp.lang.forth,comp.lang.fortran,comp.lang.misc,comp.arch Subject: Re: Assembly or .... Message-ID: <79744@sun.uucp> Date: 1 Dec 88 22:37:43 GMT References: <1388@aucs.UUCP| <729@convex.UUCP> <1961@crete.cs.glasgow.ac.uk> <7740@boring.cwi.nl> <1039@l.cc.purdue.edu> Sender: news@sun.uucp Reply-To: khb@sun.UUCP (Keith Bierman - Sun Tactical Engineering) Organization: Sun Microsystems, Mountain View Lines: 29 In article <1039@l.cc.purdue.edu> cik@l.cc.purdue.edu (Herman Rubin) writes: > >Can division be pipelined? In scalar mode on the CYBER 205, division is not >subject for pipelining. I believe that this is the case because too much of >the dividend must be retained throughout. The cydra 5 had it pipelined, but the pipe was interlocked during operation. This was said to be due to a lack of real estate (viz could have been fully pipelined if (a) not for gradual underflow (the cydra 5 was a fully ieee compliant machine), (b) there was more space it could have been done anyway. > >Even if CORDIC is not used, returning the sine and cosine would be faster in >software than two function calls. The corresponding function is in some of >the libraries I know, but I have not seen any other implementation than the >two calls. DEC's famous math$sincos does this. SunFORTRAN takes two calls (in the user code) and turns them into one call to the sun sincos routine. Unless I am mistaken this is a very old and well known optimization (which is typically invisible to the user). On many machines the cost of both is only a couple of % more than the cost of one. Keith H. Bierman It's Not My Fault ---- I Voted for Bill & Opus