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Re: [MiNT] fpu40/60 instructions

To: mikro <mikro@hysteria.sk>
Subject: Re: [MiNT] fpu40/60 instructions
From: Andreas Schwab <schwab@suse.de>
Date: Tue, 20 Jul 2004 15:29:43 +0200
Cc: mint@fishpool.com
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mikro <mikro@hysteria.sk> writes:

> does anybody know what is the difference between instructions like fsglmul,
> fsgldiv (68881/2) and fsmul, fsdiv(68040/60) ?

fsglmul/fsgldiv calculate with single float rounding mode but extended
precision exponent (i.e. more range than single float), whereas fsmul and
fsdiv calculate completely in single float format.  The difference between
the two methods is visible in the overflow handling: with fsglmul you can
multiply two values of FLT_MAX without overflow, whereas with fsmul you
would get Infinity.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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References:
- [MiNT] fpu40/60 instructions
  - From: mikro <mikro@hysteria.sk>

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