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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 --
-- --
-- B o d y --
-- --
-- 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. --
-- --
------------------------------------------------------------------------------
with Ada.Numerics.Long_Elementary_Functions;
use Ada.Numerics.Long_Elementary_Functions;
with Ada.Unchecked_Conversion;
with System.Random_Numbers; use System.Random_Numbers;
package body GNAT.Random_Numbers is
Sys_Max_Image_Width : constant := System.Random_Numbers.Max_Image_Width;
subtype Image_String is String (1 .. Max_Image_Width);
-- Utility function declarations
procedure Insert_Image
(S : in out Image_String;
Index : Integer;
V : Integer_64);
-- Insert string representation of V in S starting at position Index
---------------
-- To_Signed --
---------------
function To_Signed is
new Ada.Unchecked_Conversion (Unsigned_32, Integer_32);
function To_Signed is
new Ada.Unchecked_Conversion (Unsigned_64, Integer_64);
------------------
-- Insert_Image --
------------------
procedure Insert_Image
(S : in out Image_String;
Index : Integer;
V : Integer_64)
is
Image : constant String := Integer_64'Image (V);
begin
S (Index .. Index + Image'Length - 1) := Image;
end Insert_Image;
---------------------
-- Random_Discrete --
---------------------
function Random_Discrete
(Gen : Generator;
Min : Result_Subtype := Default_Min;
Max : Result_Subtype := Result_Subtype'Last) return Result_Subtype
is
function F is
new System.Random_Numbers.Random_Discrete
(Result_Subtype, Default_Min);
begin
return F (Gen.Rep, Min, Max);
end Random_Discrete;
------------
-- Random --
------------
function Random (Gen : Generator) return Float is
begin
return Random (Gen.Rep);
end Random;
function Random (Gen : Generator) return Long_Float is
begin
return Random (Gen.Rep);
end Random;
function Random (Gen : Generator) return Interfaces.Unsigned_32 is
begin
return Random (Gen.Rep);
end Random;
function Random (Gen : Generator) return Interfaces.Unsigned_64 is
begin
return Random (Gen.Rep);
end Random;
function Random (Gen : Generator) return Integer_64 is
begin
return To_Signed (Unsigned_64'(Random (Gen)));
end Random;
function Random (Gen : Generator) return Integer_32 is
begin
return To_Signed (Unsigned_32'(Random (Gen)));
end Random;
function Random (Gen : Generator) return Long_Integer is
function Random_Long_Integer is new Random_Discrete (Long_Integer);
begin
return Random_Long_Integer (Gen);
end Random;
function Random (Gen : Generator) return Integer is
function Random_Integer is new Random_Discrete (Integer);
begin
return Random_Integer (Gen);
end Random;
------------------
-- Random_Float --
------------------
function Random_Float (Gen : Generator) return Result_Subtype is
function F is new System.Random_Numbers.Random_Float (Result_Subtype);
begin
return F (Gen.Rep);
end Random_Float;
---------------------
-- Random_Gaussian --
---------------------
-- Generates pairs of normally distributed values using the polar method of
-- G. E. P. Box, M. E. Muller, and G. Marsaglia. See Donald E. Knuth, The
-- Art of Computer Programming, Vol 2: Seminumerical Algorithms, section
-- 3.4.1, subsection C, algorithm P. Returns half of the pair on each call,
-- using the Next_Gaussian field of Gen to hold the second member on
-- even-numbered calls.
function Random_Gaussian (Gen : Generator) return Long_Float is
G : Generator renames Gen'Unrestricted_Access.all;
V1, V2, Rad2, Mult : Long_Float;
begin
if G.Have_Gaussian then
G.Have_Gaussian := False;
return G.Next_Gaussian;
else
loop
V1 := 2.0 * Random (G) - 1.0;
V2 := 2.0 * Random (G) - 1.0;
Rad2 := V1 ** 2 + V2 ** 2;
exit when Rad2 < 1.0 and then Rad2 /= 0.0;
end loop;
-- Now V1 and V2 are coordinates in the unit circle
Mult := Sqrt (-2.0 * Log (Rad2) / Rad2);
G.Next_Gaussian := V2 * Mult;
G.Have_Gaussian := True;
return Long_Float'Machine (V1 * Mult);
end if;
end Random_Gaussian;
function Random_Gaussian (Gen : Generator) return Float is
V : constant Long_Float := Random_Gaussian (Gen);
begin
return Float'Machine (Float (V));
end Random_Gaussian;
-----------
-- Reset --
-----------
procedure Reset (Gen : out Generator) is
begin
Reset (Gen.Rep);
Gen.Have_Gaussian := False;
end Reset;
procedure Reset
(Gen : out Generator;
Initiator : Initialization_Vector)
is
begin
Reset (Gen.Rep, Initiator);
Gen.Have_Gaussian := False;
end Reset;
procedure Reset
(Gen : out Generator;
Initiator : Interfaces.Integer_32)
is
begin
Reset (Gen.Rep, Initiator);
Gen.Have_Gaussian := False;
end Reset;
procedure Reset
(Gen : out Generator;
Initiator : Interfaces.Unsigned_32)
is
begin
Reset (Gen.Rep, Initiator);
Gen.Have_Gaussian := False;
end Reset;
procedure Reset
(Gen : out Generator;
Initiator : Integer)
is
begin
Reset (Gen.Rep, Initiator);
Gen.Have_Gaussian := False;
end Reset;
procedure Reset
(Gen : out Generator;
From_State : Generator)
is
begin
Reset (Gen.Rep, From_State.Rep);
Gen.Have_Gaussian := From_State.Have_Gaussian;
Gen.Next_Gaussian := From_State.Next_Gaussian;
end Reset;
Frac_Scale : constant Long_Float :=
Long_Float
(Long_Float'Machine_Radix) ** Long_Float'Machine_Mantissa;
function Val64 (Image : String) return Integer_64;
-- Renames Integer64'Value
-- We cannot use a 'renames Integer64'Value' since for some strange
-- reason, this requires a dependency on s-auxdec.ads which not all
-- run-times support ???
function Val64 (Image : String) return Integer_64 is
begin
return Integer_64'Value (Image);
end Val64;
procedure Reset
(Gen : out Generator;
From_Image : String)
is
F0 : constant Integer := From_Image'First;
T0 : constant Integer := From_Image'First + Sys_Max_Image_Width;
begin
Reset (Gen.Rep, From_Image (F0 .. F0 + Sys_Max_Image_Width));
if From_Image (T0 + 1) = '1' then
Gen.Have_Gaussian := True;
Gen.Next_Gaussian :=
Long_Float (Val64 (From_Image (T0 + 3 .. T0 + 23))) / Frac_Scale
* Long_Float (Long_Float'Machine_Radix)
** Integer (Val64 (From_Image (T0 + 25 .. From_Image'Last)));
else
Gen.Have_Gaussian := False;
end if;
end Reset;
-----------
-- Image --
-----------
function Image (Gen : Generator) return String is
Result : Image_String;
begin
Result := (others => ' ');
Result (1 .. Sys_Max_Image_Width) := Image (Gen.Rep);
if Gen.Have_Gaussian then
Result (Sys_Max_Image_Width + 2) := '1';
Insert_Image (Result, Sys_Max_Image_Width + 4,
Integer_64 (Long_Float'Fraction (Gen.Next_Gaussian)
* Frac_Scale));
Insert_Image (Result, Sys_Max_Image_Width + 24,
Integer_64 (Long_Float'Exponent (Gen.Next_Gaussian)));
else
Result (Sys_Max_Image_Width + 2) := '0';
end if;
return Result;
end Image;
end GNAT.Random_Numbers;
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