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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Any examples of Byte Ordering Functions
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You can also do
  type source is record
    a,b,c,d : bytes;
  end record;
  for source use record
    a at 0 range 0 .. 7;
    b at 1 range 0 .. 7;
    c at 2 range 0 .. 7;
    d at 3 range 0 .. 7;
  end record;
  type target is record
    d,c,b,a : bytes;
  end record;
  for target use record
    d at 0 range 0 .. 7;
    c at 1 range 0 .. 7;
    b at 2 range 0 .. 7;
    a at 3 range 0 .. 7;
  end record;

  type dword is new interfaces.integer_32;
  type swapped_dword is new interfaces.integer_32;

  function split_dword is new ada.unchecked_conversion(dword, source);
  function make_swapped is new ada.unchecked_conversion(target, swapped_dword);

  function byte_swap(input : dword) return swapped_dword is
    s : constant source := split_dword(input);
  begin
    return make_swapped(target'(a=>s.d, b=>s.c, c=>s.b, d=>s.a));
  end byte_swap;