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From: "Makhno" <root@127.0.0.1>
Newsgroups: comp.lang.ada
Subject: Re: DLLs with GNAT
Date: Sat, 15 Oct 2005 10:50:06 +0100
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Date: 2005-10-15T09:51:48+00:00
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> I've used DLLs i created in C++ and VBA (under excel).
> I have not tried anything with Visual Studio.NET

It works fine. One thing they don't tell you is that you can get GNAT to
print out the alignment of some ADA records as its compiling, though for
some reason it seems to occasionally miss records.
To link to functions that take records as arguments, you can pass a pointer
to an equivalently-aligned C-style struct and call it with the default
C-style calling convention. If ada returns a record as the result of a
function, you must link to it using the __stdcall convention, and the struct 
is returned 'as value' to C (rather than as a pointer).

Arrays that are dimensioned [1...n] have size n (indexed 0...n-1 in C),
whereas arrays that are dimensioned [0...n] have size n+1. Easy to miss this
one (could've left work at 7 on Wednesday, but because of this I left at 8).