From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id MAA10141; Fri, 9 Nov 2001 12:28:40 +0100 (MET)
X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f
Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id MAA10454 for <caml-list@pauillac.inria.fr>; Fri, 9 Nov 2001 12:28:39 +0100 (MET)
Received: from comtv.ru (mail.comtv.ru [217.10.32.4])
	by nez-perce.inria.fr (8.11.1/8.10.0) with ESMTP id fA9BSdn05112
	for <caml-list@pauillac.inria.fr>; Fri, 9 Nov 2001 12:28:39 +0100 (MET)
Received: from [10.2.64.72] (HELO oyster2)
  by comtv.ru (CommuniGate Pro SMTP 3.4.7)
  with ESMTP id 1124505; Fri, 09 Nov 2001 14:28:38 +0300
Date: Fri, 9 Nov 2001 14:28:28 +0300 (MSK)
From: malc <malc@pulsesoft.com>
X-Sender: malc@oyster
To: "Rafael 'Dido' Sevilla" <sevillar@team.ph.inter.net>
cc: Caml List <caml-list@pauillac.inria.fr>
Subject: Re: [Caml-list] how to split up a Caml float into its component
 bytes
In-Reply-To: <20011109112909.A9417@team.ph.inter.net>
Message-ID: <Pine.LNX.4.21.0111091425280.665-100000@oyster>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-caml-list@pauillac.inria.fr
Precedence: bulk

On Fri, 9 Nov 2001, Rafael 'Dido' Sevilla wrote:

> 
> I've been writing a byte compiler for a small language using Objective
> Caml, and now am thinking about incorporating floating point support
> into the language.  I'm wondering how I would convert a floating point
> number in OCaml (which I hope I am safe in assuming is IEEE-754) into
> its equivalent bytes.  I need it to be able to output bytecode
> instructions that will load floating point constants into the virtual
> machine.  In C this is fairly trivial to do; not sure how to do it in
> OCaml.

This code is for single precission floats.

#include <string.h>
#include <caml/mlvalues.h>
#include <caml/alloc.h>

/* Kindly suggested by Xavier Leroy on Caml Mailing List */
value unpack_float (value s)
{
  union { float f; char c[4]; } buffer;
  memcpy (buffer.c, String_val (s), 4);
  return copy_double ((double) buffer.f);
}

value pack_float (value d)
{
  value s;
  union { float f; char c[4]; } buffer;

  s = alloc_string (4);
  buffer.f = (float) Double_val (d);
  memcpy (String_val (s), buffer.c, 4);
  return s;
}

module Fltstub = struct
  external pack : float -> string = "pack_float"
  external unpack : string -> float = "unpack_float"
end

-- 
mailto:malc@pulsesoft.com

-------------------
Bug reports: http://caml.inria.fr/bin/caml-bugs  FAQ: http://caml.inria.fr/FAQ/
To unsubscribe, mail caml-list-request@inria.fr  Archives: http://caml.inria.fr