Re: Novice Question on Record Representation

[zaphod.mps.ohio-state.edu!cis.ohio-state.edu!udecc.engr.udayton.edu!black bird.afit.af.mil!usafa.af.mil!kirk!cwarack@uunet.uu.net (Chris Warack <zaphod.]

Why do you say, "of course" there is an error in this?  You should be able
to layout a private type just as easily as any other -- of course, you need
knowledge of that private type which you otherwise might not need; but, you're
using a rep clause so you must need it.

However, you may be getting an error if your machine's storage unit is a byte
(like most machines).  In this case, you are laying out field A to take bytes
0 and 1; field B takes bytes 2 and 3; field C starts with byte 1 again, thus
takes bytes 1,2,3, and 4.  Bytes 1,2,3 are already allocated, however. 
That is an error.  If your storage unit is a long word (32 bits), this should
work...

-- Chris

In article <1992Dec16.225712.23791@saifr00.cfsat.honeywell.com>, lam@saifr00.cf
sat.honeywell.com (Josh Lam) writes:
|> There is a type in another package I need to use in a record in my package.
|> Unfortunately, that type is private and I need to use record representation
|> for my record.
|> 
|> package Some_Package is
|> 
|>  type Some_Int is new integer;
|>  for Some_Int'size use 16;
|> 
|>  type Some_Type is private
|> 
|>  -- etc etc
|> 
|>  private
|> 
|>   type Some_Type is new integer;
|>   for Some_Type'size use 32;
|> 
|> end Some_Package;
|> 
|> 
|> with Some_Package;
|> package My_Package is
|> 
|>  type My_Rec (Choice: Boolean := True) is record
|>    case Choice is
|>      when True =>
|>        A : Some_Package.Some_Int;
|>        B : Some_Package.Some_Int;
|>        C : Some_Package.Some_Type;
|>      when False =>
|>        D : Some_Package.Some_Int;
|>    end case;
|>  end record;
|>    
|>  for My_Rec use record
|>     A      at 0 range 0..15;
|>     B      at 0 range 16..31;
|>     C      at 1 range 0..31;     -- of course there is an error here!
|>     Choice at 2 range 0..31;
|>     D      at 0 range 0..15;
|>  end record;
|> 
|> -- etc etc
|> 
|> end My_Package;
|> 
|> 
|> I know that I cannot do the above cos C is of Some_Package.Some_Type which
|> is a private type.
|> 
|> So, other than yelling at the person and getting him to change his type
|> to public, what are my alternatives given that I need to use record
|> representation. Please also let me know some pros and cons (if any) to any
|> alternative.
|> 
|> Thanks in advance!
|> 
|> -- 
|> Josh Lam
|> Honeywell Inc
|> lam@saifr00.cfsat.honeywell.com
|>