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 20:40:08 GMT
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Original-From:
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John A. Tamplin <jat@traveller^Spamless^.com>
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Viewed:
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1404 times
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On Tue, 9 Feb 1999, dave madden 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.)
Are you linking libgcc.a? I believe it has all the math helper functions
that are required.
John A. Tamplin Traveller Information Services
jat@Traveller.COM 2104 West Ferry Way
256/705-7007 - FAX 256/705-7100 Huntsville, AL 35801
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: NQC v. LegOS / size
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| =>From: "John A. Tamplin" <jat@Traveller.COM> =>... =>On Tue, 9 Feb 1999, dave madden wrote: => =>> Yes, the H8 divide instruction can only do (16 bits)/(8 bits), so GCC =>> calls a helper routine [...] => =>Are you linking libgcc.a? I believe it (...) (25 years ago, 9-Feb-99, to lugnet.robotics)
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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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