From: Fabrice Le Fessant <lefessan@tyminouch.dyndns.org>
To: nr@eecs.harvard.edu (Norman Ramsey)
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] implementing bit vectors in OCaml
Date: Mon, 2 Jun 2003 12:10:46 +0200 [thread overview]
Message-ID: <16091.8870.562522.681942@tyminouch.dyndns.org> (raw)
In-Reply-To: <20030601170317.002EF12F9CE@flatcoat.eecs.harvard.edu>
> We have a program that is spending a lot of time in set operations,
> and we're thinking of trying an imperative implementation based on bit vectors.
> I would hope that the basis of such an implementation would be an array
> of native integers, but on scrutinizing the manual (espeically the chapter
> on interfacing to C), I have concluded that such a thing is not possible.
> Our choices appear to be
>
> * An array of native integers, which will be implemented as an array
> of pointers to native integers, because integers are boxed.
>
> * An array of tagged integers, which will be less efficient as
> dividing by 31 is more expensive than shifting.
You can also lose some space, and use only 16 bits by integer, and the division will be less expensive.
- Fabrice
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next prev parent reply other threads:[~2003-06-02 10:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-06-01 17:03 Norman Ramsey
2003-06-01 17:50 ` Ville-Pertti Keinonen
2003-06-02 8:21 ` Diego Olivier Fernandez Pons
2003-06-02 8:54 ` Hendrik Tews
2003-06-02 8:59 ` Claude Marche
2003-06-02 9:26 ` Xavier Leroy
2003-06-02 10:11 ` Marcin 'Qrczak' Kowalczyk
2003-06-02 10:10 ` Fabrice Le Fessant [this message]
2003-06-02 13:29 Gregory Morrisett
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