Message-ID:	<39F0EBB3.375FEFCE@email.com>
From:	Derek Chew <sdchew AT email DOT com>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Runtime Speed Optimization
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Date:	Sat, 21 Oct 2000 09:04:51 +0800
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

 over the past few weeks, I have been trying to develop a GUI for a
  DC Servo Motor system for my undergraduate project using DJGCC and
  Allgero... thanks to the excellent help of people like Laurence
  Withers, George Foot and the very helpful people in the Allegro
  mailing list, the project is nearing completion with some
  minor bugs still waiting to be stamped out.. but I currently have
  hit a major problem...

  The target system which I am running the GUI on is a 486DX4-100 with
  8 Meg of RAM... the system is kind of slow and the control algorithm
  (linear/non-linear/Feed-Forward) are quite mathematically complex
  and the program makes a lot of outportb called to output the control
  signals to the external control circuitry... the development of the
  control algorithm took place concurrently using a text-based
  software and the control algorithm was done in a modular fashion in
  order to allow for easy interfacing with the Allegro based GUI
  later... Currently some of the problems faced are:

  1) System's response time is way way too slow. Tried to speed things
  up by updating the display only every 1000 or even 10000 cycles but
  it is not helping

  2) I'm not very sure how to provide options to optimize the
  compiling of the software for my target platform. Going to try -O3
  but dunno what else can I do. Basically what I want to do is to
  optimize the program to run as fast as possible. Compiling time and
  program size is not an issue.

  3) Sometimes the compiling of the source is done on an old 486SX
  Laptop which if I am not mistaken does not have an FPU. Does this
  mean the code generated will always use an FPU emulator even if I
  run the code later on a 486DX4-100? and is there a way to force the
  compiler to generate code which will always use an FPU?

  thanks a lot guys!

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