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------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- G N A T . R A N D O M _ N U M B E R S -- -- -- -- S p e c -- -- -- -- Copyright (C) 2007-2009 Free Software Foundation, Inc. -- -- -- -- 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 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. -- -- -- -- 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. -- -- -- -- 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. -- -- -- ------------------------------------------------------------------------------ -- Extended pseudo-random number generation -- This package provides a type representing pseudo-random number generators, -- and subprograms to extract various distributions of numbers from them. It -- also provides types for representing initialization values and snapshots of -- internal generator state, which permit reproducible pseudo-random streams. -- The generator currently provided by this package has an extremely long -- period (at least 2**19937-1), and passes the Big Crush test suite, with the -- exception of the two linear complexity tests. Therefore, it is suitable for -- simulations, but should not be used as a cryptographic pseudo-random source -- without additional processing. -- The design of this package effects is simplified compared to the design -- of standard Ada.Numerics packages. There is no separate State type; the -- Generator type itself suffices for this purpose. The parameter modes on -- Reset procedures better reflect the effect of these routines. with System.Random_Numbers; with Interfaces; use Interfaces; package GNAT.Random_Numbers is type Generator is limited private; subtype Initialization_Vector is System.Random_Numbers.Initialization_Vector; function Random (Gen : Generator) return Float; function Random (Gen : Generator) return Long_Float; -- Return pseudo-random numbers uniformly distributed on [0 .. 1) function Random (Gen : Generator) return Interfaces.Integer_32; function Random (Gen : Generator) return Interfaces.Unsigned_32; function Random (Gen : Generator) return Interfaces.Integer_64; function Random (Gen : Generator) return Interfaces.Unsigned_64; function Random (Gen : Generator) return Integer; function Random (Gen : Generator) return Long_Integer; -- Return pseudo-random numbers uniformly distributed on T'First .. T'Last -- for various builtin integer types. generic type Result_Subtype is (<>); Default_Min : Result_Subtype := Result_Subtype'Val (0); function Random_Discrete (Gen : Generator; Min : Result_Subtype := Default_Min; Max : Result_Subtype := Result_Subtype'Last) return Result_Subtype; -- Returns pseudo-random numbers uniformly distributed on Min .. Max generic type Result_Subtype is digits <>; function Random_Float (Gen : Generator) return Result_Subtype; -- Returns pseudo-random numbers uniformly distributed on [0 .. 1) function Random_Gaussian (Gen : Generator) return Long_Float; function Random_Gaussian (Gen : Generator) return Float; -- Returns pseudo-random numbers normally distributed value with mean 0 -- and standard deviation 1.0. procedure Reset (Gen : out Generator); -- Re-initialize the state of Gen from the time of day procedure Reset (Gen : out Generator; Initiator : Initialization_Vector); procedure Reset (Gen : out Generator; Initiator : Interfaces.Integer_32); procedure Reset (Gen : out Generator; Initiator : Interfaces.Unsigned_32); procedure Reset (Gen : out Generator; Initiator : Integer); -- Re-initialize Gen based on the Initiator in various ways. Identical -- values of Initiator cause identical sequences of values. procedure Reset (Gen : out Generator; From_State : Generator); -- Causes the state of Gen to be identical to that of From_State; Gen -- and From_State will produce identical sequences of values subsequently. procedure Reset (Gen : out Generator; From_Image : String); function Image (Gen : Generator) return String; -- The call -- Reset (Gen2, Image (Gen1)) -- has the same effect as Reset (Gen2, Gen1); Max_Image_Width : constant := System.Random_Numbers.Max_Image_Width + 2 + 20 + 5; -- Maximum possible length of result of Image (...) private type Generator is limited record Rep : System.Random_Numbers.Generator; Have_Gaussian : Boolean; -- The algorithm used for Random_Gaussian produces deviates in -- pairs. Have_Gaussian is true iff Random_Gaussian has returned one -- member of the pair and Next_Gaussian contains the other. Next_Gaussian : Long_Float; -- Next random deviate to be produced by Random_Gaussian, if -- Have_Gaussian. end record; end GNAT.Random_Numbers;