OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [gcc/] [ada/] [s-rannum.ads] - Blame information for rev 826

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 281 jeremybenn
------------------------------------------------------------------------------
2
--                                                                          --
3
--                         GNAT RUN-TIME COMPONENTS                         --
4
--                                                                          --
5
--                S Y S T E M . R A N D O M _ N U M B E R S                 --
6
--                                                                          --
7
--                                 S p e c                                  --
8
--                                                                          --
9
--          Copyright (C) 2007,2009  Free Software Foundation, Inc.         --
10
--                                                                          --
11
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12
-- terms of the  GNU General Public License as published  by the Free Soft- --
13
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17
--                                                                          --
18
-- As a special exception under Section 7 of GPL version 3, you are granted --
19
-- additional permissions described in the GCC Runtime Library Exception,   --
20
-- version 3.1, as published by the Free Software Foundation.               --
21
--                                                                          --
22
-- You should have received a copy of the GNU General Public License and    --
23
-- a copy of the GCC Runtime Library Exception along with this program;     --
24
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25
-- <http://www.gnu.org/licenses/>.                                          --
26
--                                                                          --
27
-- GNAT was originally developed  by the GNAT team at  New York University. --
28
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29
--                                                                          --
30
------------------------------------------------------------------------------
31
 
32
--  Extended pseudo-random number generation
33
 
34
--  This package provides a type representing pseudo-random number generators,
35
--  and subprograms to extract various uniform distributions of numbers
36
--  from them. It also provides types for representing initialization values
37
--  and snapshots of internal generator state, which permit reproducible
38
--  pseudo-random streams.
39
 
40
--  The generator currently provided by this package has an extremely long
41
--  period (at least 2**19937-1), and passes the Big Crush test suite, with the
42
--  exception of the two linear complexity tests. Therefore, it is suitable
43
--  for simulations, but should not be used as a cryptographic pseudo-random
44
--  source without additional processing.
45
 
46
--  Note: this package is in the System hierarchy so that it can be directly
47
--  used by other predefined packages. User access to this package is via
48
--  the package GNAT.Random_Numbers (file g-rannum.ads), which also extends
49
--  its capabilities. The interfaces are different so as to include in
50
--  System.Random_Numbers only the definitions necessary to implement the
51
--  standard random-number packages Ada.Numerics.Float_Random and
52
--  Ada.Numerics.Discrete_Random.
53
 
54
with Interfaces;
55
 
56
package System.Random_Numbers is
57
 
58
   type Generator is limited private;
59
   type State is private;
60
   --  A non-limited version of a Generator's internal state
61
 
62
   function Random (Gen : Generator) return Float;
63
   function Random (Gen : Generator) return Long_Float;
64
   --  Return pseudo-random numbers uniformly distributed on [0 .. 1)
65
 
66
   function Random (Gen : Generator) return Interfaces.Unsigned_32;
67
   function Random (Gen : Generator) return Interfaces.Unsigned_64;
68
   --  Return pseudo-random numbers uniformly distributed on T'First .. T'Last
69
   --  for builtin integer types.
70
 
71
   generic
72
      type Result_Subtype is (<>);
73
      Default_Min : Result_Subtype := Result_Subtype'Val (0);
74
   function Random_Discrete
75
     (Gen : Generator;
76
      Min : Result_Subtype := Default_Min;
77
      Max : Result_Subtype := Result_Subtype'Last) return Result_Subtype;
78
   --  Returns pseudo-random numbers uniformly distributed on Min .. Max
79
 
80
   generic
81
      type Result_Subtype is digits <>;
82
   function Random_Float (Gen : Generator) return Result_Subtype;
83
   --  Returns pseudo-random numbers uniformly distributed on [0 .. 1)
84
 
85
   type Initialization_Vector is
86
     array (Integer range <>) of Interfaces.Unsigned_32;
87
   --  Provides the most general initialization values for a generator (used
88
   --  in Reset).  In general, there is little point in providing more than
89
   --  a certain number of values (currently 624).
90
 
91
   procedure Reset (Gen : out Generator);
92
   --  Re-initialize the state of Gen from the time of day
93
 
94
   procedure Reset (Gen : out Generator; Initiator : Initialization_Vector);
95
   procedure Reset (Gen : out Generator; Initiator : Interfaces.Integer_32);
96
   procedure Reset (Gen : out Generator; Initiator : Interfaces.Unsigned_32);
97
   procedure Reset (Gen : out Generator; Initiator : Integer);
98
   --  Re-initialize Gen based on the Initiator in various ways. Identical
99
   --  values of Initiator cause identical sequences of values.
100
 
101
   procedure Reset (Gen : out Generator; From_State : Generator);
102
   --  Causes the state of Gen to be identical to that of From_State; Gen
103
   --  and From_State will produce identical sequences of values subsequently.
104
 
105
   procedure Reset (Gen : out Generator; From_State : State);
106
   procedure Save  (Gen : Generator; To_State : out State);
107
   --  The sequence
108
   --     Save (Gen2, S); Reset (Gen1, S)
109
   --  has the same effect as Reset (Gen2, Gen1).
110
 
111
   procedure Reset (Gen : out Generator; From_Image : String);
112
   function Image (Gen : Generator) return String;
113
   --  The call
114
   --     Reset (Gen2, Image (Gen1))
115
   --  has the same effect as Reset (Gen2, Gen1);
116
 
117
   Max_Image_Width : constant := 11 * 624;
118
   --  Maximum possible length of result of Image (...)
119
 
120
   function Image (Of_State : State) return String;
121
   --  A String representation of Of_State. Identical to the result of
122
   --  Image (Gen), if Of_State has been set with Save (Gen, Of_State).
123
 
124
   function Value (Coded_State : String) return State;
125
   --  Inverse of Image on States
126
 
127
private
128
 
129
   N : constant := 624;
130
   --  The number of 32-bit integers in the shift register
131
 
132
   M : constant := 397;
133
   --  Feedback distance from the current position
134
 
135
   subtype State_Val is Interfaces.Unsigned_32;
136
   type State is array (0 .. N - 1) of State_Val;
137
 
138
   type Generator is limited record
139
      S : State := (others => 0);
140
      --  The shift register, a circular buffer
141
 
142
      I : Integer := N;
143
      --  Current starting position in shift register S
144
   end record;
145
 
146
end System.Random_Numbers;

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.