-- --
-- S p e c --
-- --
--- --
--- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
+-- --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
-- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
--- Note: the implementation used in this package was contributed by
--- Robert Eachus. It is based on the work of L. Blum, M. Blum, and
--- M. Shub, SIAM Journal of Computing, Vol 15. No 2, May 1986. The
--- particular choices for P and Q chosen here guarantee a period of
--- 562,085,314,430,582 (about 2**49), and the generated sequence has
--- excellent randomness properties. For further details, see the
--- paper "Fast Generation of Trustworthy Random Numbers", by Robert
--- Eachus, which describes both the algorithm and the efficient
+-- Note: the implementation used in this package was contributed by Robert
+-- Eachus. It is based on the work of L. Blum, M. Blum, and M. Shub, SIAM
+-- Journal of Computing, Vol 15. No 2, May 1986. The particular choices for P
+-- and Q chosen here guarantee a period of 562,085,314,430,582 (about 2**49),
+-- and the generated sequence has excellent randomness properties. For further
+-- details, see the paper "Fast Generation of Trustworthy Random Numbers", by
+-- Robert Eachus, which describes both the algorithm and the efficient
-- implementation approach used here.
with Interfaces;
package Ada.Numerics.Discrete_Random is
- -- Basic facilities.
+ -- The algorithm used here is reliable from a required statistical point of
+ -- view only up to 48 bits. We try to behave reasonably in the case of
+ -- larger types, but we can't guarantee the required properties. So
+ -- generate a warning for these (slightly) dubious cases.
+
+ pragma Compile_Time_Warning
+ (Result_Subtype'Size > 48,
+ "statistical properties not guaranteed for size > 48");
+
+ -- Basic facilities
type Generator is limited private;
procedure Reset (Gen : Generator);
procedure Reset (Gen : Generator; Initiator : Integer);
- -- Advanced facilities.
+ -- Advanced facilities
type State is private;
subtype Int is Interfaces.Integer_32;
subtype Rst is Result_Subtype;
- type Flt is digits 14;
+ -- We prefer to use 14 digits for Flt, but some targets are more limited
+
+ type Flt is digits Positive'Min (14, Long_Long_Float'Digits);
RstF : constant Flt := Flt (Rst'Pos (Rst'First));
RstL : constant Flt := Flt (Rst'Pos (Rst'Last));
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