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Newsgroups: comp.lang.ada
Subject: Re: calling an ada procedure from C++
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From: Ludovic Brenta <ludovic.brenta@insalien.org>
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Date: 18 Nov 2003 01:03:39 +0100
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Date: 2003-11-18T01:03:39+01:00
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I think some compilers will also return small structures in processor
registers.  They will neither use the stack not any static memory, if
they can help it.

The basic point remains: how each compiler passes structures between
efunctions is compiler-specific.  It is however possible, both in C
and in Ada, to specify the exact bit pattern for a stucture, and thus
to pass the structure back and forth.  I think the most portable way
would be to pass pointers to the structures (as earlier suggested) but
if the OT uses GNAT (where the compiler handles both C and Ada), there
may be more efficient ways using representation clauses and Pragma
Convention.

BTW, C++ is a different beast altogether.  I would avoid it if
possible, especially if the C++ struct is really a class with methods
and parents or descendants.  Better stick with a strictly C struct.

My 2 cents.

-- 
Ludovic Brenta.