Subject:
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Re: NQC v. LegOS / size
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 9 Feb 1999 18:19:12 GMT
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Viewed:
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1373 times
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dave madden <dhm@paradigm.webvision.com> wrote:
> Yes, the H8 divide instruction can only do (16 bits)/(8 bits), so GCC
> calls a helper routine when you attempt to divide an integer by
> another integer. (Same thing with multiplication: the hardware can
> only do (8 bits) x (8 bits) -> (16 bits), so GCC often calls a helper
> function for that, too.) Powers of two (division & multiplication)
> can be converted to shifts, and multiplication/division by a constant
> can often be turned into a combination of shifts and adds; GCC will do
> that if it thinks the combination will be more efficient than a
> generalized routine.
>
> I haven't had need of any complicated math, so I haven't written the
> helper routines; maybe Markus has some. (Alternatively, I believe
> Kekoa identified some math routines in the RCX ROM...it might be
> possible to use those.)
Actually, I have the wrappers for GCC. I have been busy with other stuff,
but I have been meaning to release my RCX code for a while now. I spent
the morning packaging up my development environment, which now lives at:
http://graphics.stanford.edu/~kekoa/rcx/tools.html#Librcx
In particular, I provide the following files:
divhi3.c modhi3.c mulhi3.c udivhi3.c umodhi3.c
divsi3.c modsi3.c mulsi3.c udivsi3.c umodsi3.c
I also provide memcpy.c and memset.c, which are also used by GCC.
Have at it.
-Kekoa
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Message is in Reply To:
 | | Re: NQC v. LegOS / size
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| =>From: Ben Laurie <ben@algroup.co.uk> =>... =>Markus L. Noga wrote: =>> Apart from the limitations imposed by H8 architecture (an 8/16 bit =>> platform with the usual constraints on integer length, available memory =>> and library functions), (...) (25 years ago, 9-Feb-99, to lugnet.robotics)
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