Date:	Wed, 15 Mar 2000 17:22:16 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
cc:	djgpp-workers AT delorie DOT com
Subject:	Re: Unnormals???
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On Wed, 15 Mar 2000, Hans-Bernhard Broeker wrote:

> > Perhaps, it would be preferable, to print "nan(unnormal)" for the 
> > unnormal case, to be std conform. 
> 
> *If* an unnormal is a NaN, yes.

How can one tell?  If the standard doesn't define what is a NaN (as I 
think it doesn't), then the answer is platform-dependent, and we are 
back to the Intel manuals which define this.

> The question still hovering in my head
> would then be what the difference is between a subnormal (supposed to be
> detectable by C99 functions) and an unnormal (mentioned nowhere in the
> whole draft). I remember having discussed this before, on this list, but
> not the details...

Let me remind you.  Unnormal (a name I picked up from Robert Hummel's 
superb "The Processor and Coprocessor" book) is a denormal with a biased 
exponent greater than zero.  In other words, it's a long double number 
whose mantissa's MSB is zero, but whose unbiased exponent is greater than 
the minimum supported exponent.

> Subnormals as defined by C99 are fp numbers with smallest possible
> exponent, and a mantissa smaller than 0.5 (i.e. no leading one-bit). These
> can only happen for 'long double', indeed, as the other formats use a
> hidden leading one-bit for the mantissa.

Likewise for the unnormal: it can only happen for a long double.

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