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From: "Stuart" <stuart@0.0>
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Subject: Re: How to put 200 into an integer sub-type of 16 bits (code
 included)
Date: Thu, 15 Jan 2009 12:40:38 -0000
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Date: 2009-01-15T12:40:38+00:00
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"ChristopherL" <clusardi2k@aol.com> wrote in message 
news:1a2b31ac-cf6b-44e3-85b7-04594460db87@d36g2000prf.googlegroups.com...
<snip>
> So, what is the proper way to store a number (never being greater
> than 200.5) in a 8 bit short number as outlined above?

then

"Stuart" <stuart@0.0> wrote in message 
news:496f03e2$1_1@glkas0286.greenlnk.net...
> OK - there is no 'proper' way, there are several ways, each of which has
> advantages and disadvantages.
<snip>

To add to what I wrote before, and depending on what you are trying to 
achieve, you might find the following Ada code of interest:

with Ada.Unchecked_Conversion;
procedure ada_main is
   type Flt is digits 7 range -1000.0 .. 1000.0;  -- !!! or whatever!

   -- The condition we need to allow the range 0.0..200.0 to be stored with
   -- most precision in 8 bits is:
   --      255 * small > 200.0 - small/2
   --   => 255.5 * small > 200.0
   --   => small > 200.0 / 255.5
   Fxd_Small : constant := 0.782778865;
      -- !!! There seem to be some issues with GNAT debugger using an 
expression here!

   type Fxd is delta Fxd_Small range 0.0 .. 200.0;
   for  Fxd'small use Fxd_Small;
   for  Fxd'size use 8;

   type Int is mod 256;  -- In case you really want the underlying 'integer' 
representation
   for  Int'size use 8;

   function to_Int is new Ada.Unchecked_Conversion(Source => Fxd, Target => 
Int);

   -- Create some volatile variables to force code to be generated.
   X : Flt;
   pragma volatile(X);
   Y : Fxd;
   for Y'size use 8;
   pragma volatile(Y);

   Z : Int;
   for Z'size use 8;
   pragma volatile(Z);

begin
   X := 200.0;
   Y := Fxd(X);    -- 199.6086
   -- Note: Read up about model numbers !!!
   -- This is the closest model number to 200.0 for Fxd.
   Z := to_Int(Y);  -- 255
end ada_main;

Regards
   Stuart