Re: using 'storage_size ?

["Alex Xela" <xela2@free.fr>]

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Yes, but the gnat strategy should not matter with the fact that when I
define a pool of 8 Mo, I should be able to allocate at least 5Mo.
Alex.

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"Robert I. Eachus" <rieachus@comcast.net> a �crit dans le message de news:
3F89E26E.40705@comcast.net...
> Alex Xela wrote:
> >
> > with ada.text_io,Unchecked_Deallocation,Ada.Exceptions;
> > procedure garbage is
> >    ko : constant := 1024;
> >    Mo : constant := ko*ko;
> ...
> >    declare
> >       type local_ptr is access tab_byte;
> >       for local_ptr'storage_size use Mo*8;--[line 20]GNAT 3.15p raised
> > STORAGE_ERROR : EXCEPTION_STACK_OVERFLOW
>
> Read the fine manual.  In this case the gnat_rm will point you to
> System.Pool_Size in s-poosiz.ads which says:
>
> --------------------------------------------------------------------------
---
>     ------------------------
>     -- Stack_Bounded_Pool --
>     ------------------------
>
>     --  Allocation strategy:
>
>     --    Pool is a regular stack array, no use of malloc
>     --    user specified size
>     --    Space of pool is globally reclaimed by normal stack management
>
>     --  Used in the compiler for access types with 'STORAGE_SIZE rep.
clause
>     --  Only used for allocating objects of the same type.
>
> --------------------------------------------------------------------------
--
>
> Translation, when you use 'Storage_Size in GNAT to set the storage for a
> type, the compiler takes that as a directive to allocate a
> local_ptr'storage_size array on the stack, in this case as part of the
> stack frame for the declare block.  If you comment the line out, the
> storage designated by local_ptr values will be allocated on the heap
> when new is called.
>
> I suspect that you need to grow the stack size if you want to grab a
> megabyte in one chunk.
>
> --
>                                                      Robert I. Eachus
>
> "Quality is the Buddha. Quality is scientific reality. Quality is the
> goal of Art. It remains to work these concepts into a practical,
> down-to-earth context, and for this there is nothing more practical or
> down-to-earth than what I have been talking about all along...the repair
> of an old motorcycle."  -- from Zen and the Art of Motorcycle
> Maintenance by Robert Pirsig
>