At 03:37 PM 11/2/2005 -0800, you wrote:
>I need to improve on the speed of some
>arbitrary-precision division and multiplication
>routines written for the CCS (CCSinfo.com) compiler in
>C code for the PIC18F8722.

FWIW, last time I looked (<mumble> months ago), I was
not able to find a C compiler for an 8-bit class micro
with 64 bit floating point numbers.

At the time I did have an application where 32 bits was
pretty marginal (easily verified in simulations using
C double variables) because of numerical issues.

>I would like to find a 64/64 bit or 64/48 bit fixed or
>floating point division routine in assembly for the
>PIC.  I also require 48 bit multiplication.  So far I
>have not had much luck in my search.  Does anybody
>know if such a routine has been written?  I require a
>great deal of precision in my application.  I am a
>hardware engineer, assembly language is not my
>specialty, so I would prefer not to reinvent the wheel
>if possible.  The Matlab equations I must perform on
>the PIC are attached.

I have not tried to analyze what you are doing.. but if
you want to sit down and write such routines, it will
probably be fairly easy. Try to avoid division as much
as possible (entirely if you can), as it's invariably quite
a bit slower than multiplication, especially if the 8x8
multiplier in the 18F is used to speed the multiplication
routines.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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