Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!apple!portal!atari!kbad
From: kbad@atari.UUCP (Ken Badertscher)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: Floating Pt. Math with a 68881 not always faster
Message-ID: <2271@atari.UUCP>
Date: 2 Sep 90 23:56:44 GMT
References: <8379@ncar.ucar.edu>
Organization: Atari Corp., Sunnyvale, CA
Lines: 21

moses@hao.ucar.edu (Julie Moses) writes:


|     While more complex math functions, such as transcendentals and 
|square root really show a speed increase, adding or multiplying two
|floating point numbers do not show any speed increase over just
|doing it with the 68000 chip. Matter of fact some of my functions
|that do repetitive mulitply and additions with floats (without more
|complex functions) are significantly slower when using the math 
|copressor. 

Sounds to me like the libraries were not properly implemented to take
best advantage of the peripheral 68881.  In series of tests that I did
when working on a homemade set of bindings for Megamax Laser C some time
ago, I sometimes noticed that the speedups weren't all that
sensational... The timings I did were /never/ slower when using the
68881, though.  And the Megamax floating point routines are /fast/.
-- 
   |||   Ken Badertscher  (ames!atari!kbad)
   |||   Atari R&D System Software Engine
  / | \  #include <disclaimer>