Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: HS/Forth
Message-ID: <693.UUL1.3#5129@willett.UUCP>
Date: 22 Mar 90 02:43:08 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 37


 Date: 03-20-90 (21:48)              Number: 56 (Echo)
   To: BILL MCCARTHY                 Refer#: 55
 From: JULIAN NOBLE                    Read: NO
 Subj: FORTE                         Status: PUBLIC MESSAGE

 Dear Mr. McCarthy,

 I have checked your timings and of course you are correct.  The code
 produced by the FORTRAN module of FORTE is slow compared with working
 directly with the co-processor.  There are several reasons for this:

 1.  In order to optimize FORTRAN, you need to know the types of
 variables at compile time.
 2.  The IFSTACK module, that manages the software floating stack, has
 not been optimized.  All the memory transfers are bytewise, e.g. And a
 lot of memory thrashing is needed.  Think of the IFSTACK (which is the
 main bottleneck -- the generic operators produce relatively little 
 speed penalty) as a pedagogic tool and/or a convenience.  The proper
 way to do it would be to extend the hardware stack on the 80x87 chip
 into memory.  Unfortunately, as Palmer and Morse note in The 8087
 Primer, the instruction set gives no hooks for easily extending the
 80x87 stack.  All the approaches I have tried so far have been pretty
 cumbersome.

 So FORTE is not intended to produce optimized code.  If you need speed,
 you hand-code the inner loops.  FORTE lets you do quick-and-dirty cal-
 culations easily, a la interpreted BASIC. 

 I am rewriting FORTE to reduce its code size and workspace.  I will put 
 some effort into the generic data stack manager to reduce the speed
 penalty, if people are interested. 

 Best regards,   Julian V. Noble  (bitnet JVN@VIRGINIA)
-----
This message came from GEnie via willett through a semi-automated process.
Report problems to: 'uunet!willett!dwp' or 'willett!dwp@gateway.sei.cmu.edu'