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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Minimum Record Size?  LONG
References: <vaj0t9m90a568d@corp.supernews.com>
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Date: 2003-04-25T21:51:35+00:00
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>Here is an approach that, while verbose, is written to be understandable
>by the reader.
  If the reader is careful and willing to study a shorter piece of code,
then, in the spirit of the OP's first try
>>       -- assemble them into one segment
>>       Segment := (Shift_Left(Part_1, 18) and 16#fc0000#) or
>>                  (Shift_Left(Part_2, 12) and 16#03f000#) or
>>                  (Shift_Left(Part_3,  6) and 16#000fc0#) or
>>                  (Shift_left(Part_4,  0) and 16#00003f#)   ;
>>
>>       -- split segment into three eight-bit hunks
>>       Val_1 := (Shift_Right(Segment and 16#ff0000#, 16));
>>       Val_2 := (Shift_Right(Segment and 16#00ff00#,  8));
>>       Val_3 := (Shift_Right(Segment and 16#0000ff#,  0));

we can modify the function to:
>  function Four_Sixes_To_Three_Eights (X : Four_Sixes)
>    return Three_Eights
>  is
>  begin
     return (1=>  Eight(x(1))*4          + Eight(x(2))/16,
             2=> (Eight(x(2)) mod 16)*16 + Eight(x(3))/4,
             3=> (Eight(x(3)) mod 4)*64  + Eight(x(4)));
>  end Four_Sixes_To_Three_Eights;