Message-ID: <c=GB%a=_%p=Indigo_Active_Vi%l=CRIANLARICH-970304101819Z-27@crianlarich.Indigo>
From: Robert Humphris <r DOT humphris AT indigo-avs DOT com>
To: "'djGpp list'" <djgpp AT delorie DOT com>
Subject: MMX
Date: Tue, 4 Mar 1997 10:18:19 -0000
Encoding: 49 TEXT

I know that this is not related to the topic, but it may be something
that should be
thought about...

MMX whatever is stands for ( I have heard several versions ) is the
addition to the Pentium
of some rather natty hardware, in the form of a SIMD parallel processing
module.
Single Instruction Multiple Data is basically the cheapest form of
parallel processing to do,
it means that multiple values can be processed at the same time, for
instance:

for( i=0; i<7; i++ )
{
  array[i] = array[i] ^ 20;
}

this would take eight iterations in a von Neuman architecture machine
but only one in a SIMD
machine ( as long as their is provision to take 8 values as there is in
the MMX ).  The result is huge speed 
up factors when performing tasks such as de/compressing, image
processing, 3d image manipulation, etc.

The question is, will DJGPP need to support this in the future?  I think
that it will, as the Parallel capability
of future chips is going to be expanded upon MMX2 is already being
tested, although what form this will take
I do not know.

Personal I think that it should be an extra set of C functions that
provide the support, parallel scheduling, 
and optimization is still the stuff of Doctatorial reseach so I don't
imagine that we will be seeing '-03SIMD'
switches on the command line just yet, but I believe that we need to
address the issue of how a set of
parallel commands would be indicated ( is there any news from MS,
Borland, or Watcom as to how they plan
to do this? they will have had access to the chip for much longer than
us ).  We could go for something
akin to that of Occam2 where the function : PAR( i=0; i<20; i++ )
indicates that the next 20 instructions
are to be performed in parallel.

Your thoughts/comments please

Rob Humphris