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Subject: Re: Java wrappers around Ada?
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James Alan Farrell wrote:
> On the C side things are a bit messy.  Out and in/out parameters become 
> pointers.  This works rather better than I would've thought (probably 
> the pragma forces such parameters to be pointers where they would not 
> always be otherwise).  But even so, we have a lot of C functions with 
> void * parameters instead of typed pointers and ints instead of Boolean, 
> etc.

ARM B.3 defines how parameters should be passed to a convention-C subprogram.

> One interesting problem we had was converting Ada access types to C 
> pointers.  An Ada access type is a higher level construct than a C 
> pointer, which means it may or might not actually "point" to the desired 
> location in memory.  What we found in practice is that arrays that are 
> sized dynamically have a 64 bit entity in which the first 32 bits do 
> point to the object of interest.

You can apply pragma Convention (C, ...); to an Ada access type to ensure that 
it is C compatible.

-- 
Jeff Carter
"Ditto, you provincial putz?"
Blazing Saddles
86