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From: nebbe@lglsun.epfl.ch (Robb Nebbe)
Newsgroups: comp.lang.ada
Subject: Re: Interfaces.C
Date: 2 Nov 1994 13:34:17 GMT
Organization: Ecole Polytechnique Federale de Lausanne
Sender: nebbe@lglsun3.epfl.ch (Robb Nebbe)
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References: <395o3q$2j1@wynkyn.ecs.soton.ac.uk>
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Keywords: Ada9X
Date: 1994-11-02T13:34:17+00:00
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In article <395o3q$2j1@wynkyn.ecs.soton.ac.uk>, kst@ecs.soton.ac.uk (Ken Thomas) writes:
|> I am attempting to write an Ada9X interface for a C function
|> with specification
|> 
|> void foo(int *a, int l)
|> 
|> the aim being to pass an integer array to the C-function. What is the
|> correct usage of the package Interfaces.C and its children?
|> 

If you just want to pass parameters to the C function you would write:

  type Int_Array is array( Natural range <> ) of C.int
  -- the range could be anything but C will treat it as starting at 0

  procedure foo( a : in Int_Array; l : in C.int );
  pragma Import( C, foo );


The array a will be passed by reference and l by value automatically.
The rules for how parameters are passed to a C program are defined
in Ada9x making it easy to abstract away from C's low-level calling
interface.

- Robb Nebbe