-------------------------------------------------------------------------------
--- --
--- GNAT RUN-TIME COMPONENTS --
--- --
--- A D A . N U M E R I C S . D I S C R E T E _ R A N D O M --
--- --
--- S p e c --
--- --
--- $Revision: 1.1.16.1 $
--- --
--- Copyright (C) 1992-2001 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 --
--- apply solely to the contents of the part following the private keyword. --
--- --
--- 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- --
--- 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. --
--- --
--- 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. --
--- --
--- 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
--- implementation approach used here.
-
-with Interfaces;
-
-generic
- type Result_Subtype is (<>);
-
-package Ada.Numerics.Discrete_Random is
-
- -- Basic facilities.
-
- type Generator is limited private;
-
- function Random (Gen : Generator) return Result_Subtype;
-
- procedure Reset (Gen : Generator);
- procedure Reset (Gen : Generator; Initiator : Integer);
-
- -- Advanced facilities.
-
- type State is private;
-
- procedure Save (Gen : Generator; To_State : out State);
- procedure Reset (Gen : Generator; From_State : State);
-
- Max_Image_Width : constant := 80;
-
- function Image (Of_State : State) return String;
- function Value (Coded_State : String) return State;
-
-private
- subtype Int is Interfaces.Integer_32;
- subtype Rst is Result_Subtype;
-
- type Flt is digits 14;
-
- RstF : constant Flt := Flt (Rst'Pos (Rst'First));
- RstL : constant Flt := Flt (Rst'Pos (Rst'Last));
-
- Offs : constant Flt := RstF - 0.5;
-
- K1 : constant := 94_833_359;
- K1F : constant := 94_833_359.0;
- K2 : constant := 47_416_679;
- K2F : constant := 47_416_679.0;
- Scal : constant Flt := (RstL - RstF + 1.0) / (K1F * K2F);
-
- type State is record
- X1 : Int := Int (2999 ** 2);
- X2 : Int := Int (1439 ** 2);
- P : Int := K1;
- Q : Int := K2;
- FP : Flt := K1F;
- Scl : Flt := Scal;
- end record;
-
- type Generator is limited record
- Gen_State : State;
- end record;
-
-end Ada.Numerics.Discrete_Random;