Ethereal-dev: Re: [Ethereal-dev] Handling DOUBLES

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From: Frank Singleton <frank.singleton@xxxxxxxxxxxx>
Date: Fri, 06 Apr 2001 09:16:56 -0500
Jeff Parker wrote:
> 
> Frank -
>         The raw counts are important, but for
> floating point the position and meanings of
> the mantissa and exponent are also important.
> (Which base?  How does the exponent express
> positive numbers? and so on)
> 

Hi,

Hopefully his helps...

<snip from some old doc...>


eg:

For single-precision float values the exponent is 8 bits long, comprising e1 and e2 in 
the figure, where the 7 bits in e1 are most significant. The exponent is represented as 
excess 127. The fractional mantissa (f1 - f3) is a 23-bit value f where 1.0 <= f < 2.0, f1 
being most significant and f3 being least significant. The value of a normalized number 
is described by:

�1^sign x 2^(exponent � 127) x (1 + fraction)

And similar formulas for other float types...but with different
"exponent" offset values.

/ Frank


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