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(*                                                                     *)
(*                           Objective Caml                            *)
(*                                                                     *)
(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
(*                                                                     *)
(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
(*  en Automatique.  All rights reserved.  This file is distributed    *)
(*  under the terms of the GNU Library General Public License, with    *)
(*  the special exception on linking described in file ../LICENSE.     *)
(*                                                                     *)
(***********************************************************************)

(* $Id$ *)

(** Processor-native integers.

   This module provides operations on the type [nativeint] of
   signed 32-bit integers (on 32-bit platforms) or
   signed 64-bit integers (on 64-bit platforms).
   This integer type has exactly the same width as that of a [long]
   integer type in the C compiler.  All arithmetic operations over
   [nativeint] are taken modulo 2{^32} or 2{^64} depending
   on the word size of the architecture.

   Performance notice: values of type [nativeint] occupy more memory
   space than values of type [int], and arithmetic operations on
   [nativeint] are generally slower than those on [int].  Use [nativeint]
   only when the application requires the extra bit of precision
   over the [int] type. 
*)

val zero : nativeint
(** The native integer 0.*)

val one : nativeint
(** The native integer 1.*)

val minus_one : nativeint
(** The native integer -1.*)

external neg : nativeint -> nativeint = "%nativeint_neg"
(** Unary negation. *)

external add : nativeint -> nativeint -> nativeint = "%nativeint_add"
(** Addition. *)

external sub : nativeint -> nativeint -> nativeint = "%nativeint_sub"
(** Subtraction. *)

external mul : nativeint -> nativeint -> nativeint = "%nativeint_mul"
(** Multiplication. *)

external div : nativeint -> nativeint -> nativeint = "%nativeint_div"
(** Integer division.  Raise [Division_by_zero] if the second 
   argument is zero. *)

external rem : nativeint -> nativeint -> nativeint = "%nativeint_mod"
(** Integer remainder.  If [x >= 0] and [y > 0], the result
   of [Nativeint.rem x y] satisfies the following properties:
   [0 <= Nativeint.rem x y < y] and
   [x = Nativeint.add (Nativeint.mul (Nativeint.div x y) y) (Nativeint.rem x y)].
   If [y = 0], [Nativeint.rem x y] raises [Division_by_zero].
   If [x < 0] or [y < 0], the result of [Nativeint.rem x y] is
   not specified and depends on the platform. *)

val succ : nativeint -> nativeint
(** Successor.
   [Nativeint.succ x] is [Nativeint.add x Nativeint.one]. *)

val pred : nativeint -> nativeint
(** Predecessor.
   [Nativeint.pred x] is [Nativeint.sub x Nativeint.one]. *)

val abs : nativeint -> nativeint
(** Return the absolute value of its argument. *)

val size : int
(** The size in bits of a native integer.  This is equal to [32]
   on a 32-bit platform and to [64] on a 64-bit platform. *)

val max_int : nativeint
(** The greatest representable native integer,
   either 2{^31} - 1 on a 32-bit platform,
   or 2{^63} - 1 on a 64-bit platform. *)

val min_int : nativeint
(** The greatest representable native integer,
   either -2{^31} on a 32-bit platform,
   or -2{^63} on a 64-bit platform. *)

external logand : nativeint -> nativeint -> nativeint = "%nativeint_and"
(** Bitwise logical and. *)

external logor : nativeint -> nativeint -> nativeint = "%nativeint_or"
(** Bitwise logical or. *)

external logxor : nativeint -> nativeint -> nativeint = "%nativeint_xor"
(** Bitwise logical exclusive or. *)

val lognot : nativeint -> nativeint
(** Bitwise logical negation *)

external shift_left : nativeint -> int -> nativeint = "%nativeint_lsl"
(** [Nativeint.shift_left x y] shifts [x] to the left by [y] bits.
   The result is unspecified if [y < 0] or [y >= bitsize],
   where [bitsize] is [32] on a 32-bit platform and
   [64] on a 64-bit platform. *)

external shift_right : nativeint -> int -> nativeint = "%nativeint_asr"
(** [Nativeint.shift_right x y] shifts [x] to the right by [y] bits.
   This is an arithmetic shift: the sign bit of [x] is replicated
   and inserted in the vacated bits.
   The result is unspecified if [y < 0] or [y >= bitsize]. *)

external shift_right_logical :
  nativeint -> int -> nativeint = "%nativeint_lsr"
(** [Nativeint.shift_right_logical x y] shifts [x] to the right
   by [y] bits.
   This is a logical shift: zeroes are inserted in the vacated bits
   regardless of the sign of [x].
   The result is unspecified if [y < 0] or [y >= bitsize]. *)


external of_int : int -> nativeint = "%nativeint_of_int"
(** Convert the given integer (type [int]) to a native integer
   (type [nativeint]). *)

external to_int : nativeint -> int = "%nativeint_to_int"
(** Convert the given native integer (type [nativeint]) to an
   integer (type [int]).  The high-order bit is lost during
   the conversion. *)

external of_float : float -> nativeint = "nativeint_of_float"
(** Convert the given floating-point number to a native integer,
   discarding the fractional part (truncate towards 0).
   The result of the conversion is undefined if, after truncation,
   the number is outside the range
   \[{!Nativeint.min_int}, {!Nativeint.max_int}\]. *)
       
external to_float : nativeint -> float = "nativeint_to_float"
(** Convert the given native integer to a floating-point number. *)

external of_int32 : int32 -> nativeint = "%nativeint_of_int32"
(** Convert the given 32-bit integer (type [int32])
   to a native integer. *)

external to_int32 : nativeint -> int32 = "%nativeint_to_int32"
(** Convert the given native integer to a
   32-bit integer (type [int32]).  On 64-bit platforms,
   the 64-bit native integer is taken modulo 2{^32},
   i.e. the top 32 bits are lost.  On 32-bit platforms,
   the conversion is exact. *)

external of_string : string -> nativeint = "nativeint_of_string"
(** Convert the given string to a native integer.
   The string is read in decimal (by default) or in hexadecimal,
   octal or binary if the string begins with [0x], [0o] or [0b]
   respectively.
   Raise [Failure "int_of_string"] if the given string is not
   a valid representation of an integer. *)

val to_string : nativeint -> string
(** Return the string representation of its argument, in decimal. *)

external format : string -> nativeint -> string = "nativeint_format"
(** [Nativeint.format fmt n] return the string representation of the
   native integer [n] in the format specified by [fmt].
   [fmt] is a [Printf]-style format containing exactly
   one [%d], [%i], [%u], [%x], [%X] or [%o] conversion specification.
   This function is deprecated; use {!Printf.sprintf} with a [%nx] format
   instead. *)