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From: "Wiljan Derks" <Wiljan.Derks@gmail.com>
Newsgroups: comp.lang.ada
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Subject: Re: How to check a Float for NaN
Date: Tue, 6 May 2008 20:45:47 +0200
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Date: 2008-05-06T20:45:47+02:00
List-Id: <comp.lang.ada>

The following code works fine for us:

   type Ieee_Short_Real is
      record
         Mantisse_Sign : Integer range 0 .. 1;
         Exponent      : Integer range 0 .. 2 **  8 - 1;
         Mantisse      : Integer range 0 .. 2 ** 23 - 1;
      end record;

   for Ieee_Short_Real use
      record
         Mantisse_Sign at 0 range 31 .. 31;
         Exponent      at 0 range 23 .. 30;
         Mantisse      at 0 range  0 .. 22;
      end record;

   function Valid_Real (Number : Float) return Boolean is
      function To_Ieee_Short_Real is
         new Ada.Unchecked_Conversion (Float, Ieee_Short_Real);
   begin
      return To_Ieee_Short_Real (Number).Exponent /= 255;
   end Valid_Real;

Wiljan