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Date: Mon, 5 Aug 2002 11:29:56 +0200
From: Xavier Leroy <xavier.leroy@inria.fr>
To: Thorsten Ohl <ohl@physik.uni-wuerzburg.de>
Cc: polux moon <polux_moon@hotmail.com>, caml-list@inria.fr
Subject: Re: [Caml-list] read a float(double)  in a file in a binary file
Message-ID: <20020805112956.B7554@pauillac.inria.fr>
References: <F186SweAcWKHlQAiPgT0000ad6a@hotmail.com> <15690.48147.967042.16431@wptx47.physik.uni-wuerzburg.de>
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In-Reply-To: <15690.48147.967042.16431@wptx47.physik.uni-wuerzburg.de>; from ohl@physik.uni-wuerzburg.de on Fri, Aug 02, 2002 at 07:06:27PM +0200
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> > How can I read a float (double) in a binary format (output of a
> > programe in c ) from a file ?

Here is a sample implementation, without any unsafe operation.
You didn't say whether your numbers are in big or little endian
representation, so the code handles both.

Hope this helps,

- Xavier Leroy

let output_float_big_endian oc f =
  let n = ref (Int64.bits_of_float f) in
  for i = 0 to 7 do
    output_byte oc (Int64.to_int (Int64.shift_right_logical !n 56));
    n := Int64.shift_left !n 8
  done

let output_float_little_endian oc f =
  let n = ref (Int64.bits_of_float f) in
  for i = 0 to 7 do
    output_byte oc (Int64.to_int !n);
    n := Int64.shift_right_logical !n 8
  done

let input_float_big_endian oc =
  let n = ref Int64.zero in
  for i = 0 to 7 do
    let b = input_byte oc in
    n := Int64.logor (Int64.shift_left !n 8) (Int64.of_int b)
  done;
  Int64.float_of_bits !n

let input_float_little_endian oc =
  let n = ref Int64.zero in
  for i = 0 to 7 do
    let b = input_byte oc in
    n := Int64.logor !n (Int64.shift_left (Int64.of_int b) (i*8))
  done;
  Int64.float_of_bits !n




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