Re: [Chicken-users] Importing alien bignums

[Kon Lovett]

On Jun 13, 2006, at 8:05 AM, John Cowan wrote:

> My Q-language egg is coming along nicely, and I've run into an  
> issue with
> bignums vs. FFI.  When the numbers egg is installed, Chicken  
> represents
> bignums as mpz_t objects from the GMP.  Q has bignums as standard,
> and uses the same representation and library.
>
> However, there is not surprisingly no support for bignums in the FFI.
> How can I persuade Chicken to treat a c-pointer coming from the FFI  
> as an
> (mpz_t *) and consider it to be a Scheme number?  (Obviously this  
> would
> only be done if the full-numeric-tower: feature is available.)
>
> Naturally, bignums have to be copied both ways so that the two garbage
> collectors don't collide.

The interface the numbers egg uses isn't public. You would want to  
use 'alloc_bignum*', etc. routines. In the short term maybe just copy- 
and-paste the 'numbers-c.[ch]' stuff. Then coerce the types in your  
bridge explicitly.

But, yeah, something must be done for better integration of the full- 
numeric-tower.

Q is pretty neat. Good luck.

Kon

> --
> Take two turkeys, one goose, four               John Cowan
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> ~cowan
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>
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