| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME COMPONENTS -- |
| -- -- |
| -- A D A . N U M E R I C S . F L O A T _ R A N D O M -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2002 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; |
| |
| package Ada.Numerics.Float_Random is |
| |
| -- Basic facilities |
| |
| type Generator is limited private; |
| |
| subtype Uniformly_Distributed is Float range 0.0 .. 1.0; |
| |
| function Random (Gen : Generator) return Uniformly_Distributed; |
| |
| 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 |
| type Int is new Interfaces.Integer_32; |
| |
| -- 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); |
| |
| K1 : constant := 94_833_359; |
| K1F : constant := 94_833_359.0; |
| K2 : constant := 47_416_679; |
| K2F : constant := 47_416_679.0; |
| Scal : constant := 1.0 / (K1F * K2F); |
| |
| type State is record |
| X1 : Int := 2999 ** 2; -- Square mod p |
| X2 : Int := 1439 ** 2; -- Square mod q |
| P : Int := K1; |
| Q : Int := K2; |
| X : Int := 1; |
| Scl : Flt := Scal; |
| end record; |
| |
| type Generator is limited record |
| Gen_State : State; |
| end record; |
| |
| end Ada.Numerics.Float_Random; |
