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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/ada/s-rannum.ads | |
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Diffstat (limited to 'gcc/ada/s-rannum.ads')
-rw-r--r-- | gcc/ada/s-rannum.ads | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/gcc/ada/s-rannum.ads b/gcc/ada/s-rannum.ads new file mode 100644 index 000000000..0d2a7e9de --- /dev/null +++ b/gcc/ada/s-rannum.ads @@ -0,0 +1,153 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT RUN-TIME COMPONENTS -- +-- -- +-- S Y S T E M . R A N D O M _ N U M B E R S -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 2007-2010, 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 uniform 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. + +-- Note: this package is in the System hierarchy so that it can be directly +-- used by other predefined packages. User access to this package is via +-- the package GNAT.Random_Numbers (file g-rannum.ads), which also extends +-- its capabilities. The interfaces are different so as to include in +-- System.Random_Numbers only the definitions necessary to implement the +-- standard random-number packages Ada.Numerics.Float_Random and +-- Ada.Numerics.Discrete_Random. + +with Interfaces; + +package System.Random_Numbers is + + type Generator is limited private; + type State is private; + -- A non-limited version of a Generator's internal state + + 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.Unsigned_32; + function Random (Gen : Generator) return Interfaces.Unsigned_64; + -- Return pseudo-random numbers uniformly distributed on T'First .. T'Last + -- for 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) + + type Initialization_Vector is + array (Integer range <>) of Interfaces.Unsigned_32; + -- Provides the most general initialization values for a generator (used + -- in Reset). In general, there is little point in providing more than + -- a certain number of values (currently 624). + + procedure Reset (Gen : Generator); + -- Re-initialize the state of Gen from the time of day + + procedure Reset (Gen : Generator; Initiator : Initialization_Vector); + procedure Reset (Gen : Generator; Initiator : Interfaces.Integer_32); + procedure Reset (Gen : Generator; Initiator : Interfaces.Unsigned_32); + procedure Reset (Gen : 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 : 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 : Generator; From_State : State); + procedure Save (Gen : Generator; To_State : out State); + -- The sequence + -- Save (Gen2, S); Reset (Gen1, S) + -- has the same effect as Reset (Gen2, Gen1). + + procedure Reset (Gen : 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 := 11 * 624; + -- Maximum possible length of result of Image (...) + + function Image (Of_State : State) return String; + -- A String representation of Of_State. Identical to the result of + -- Image (Gen), if Of_State has been set with Save (Gen, Of_State). + + function Value (Coded_State : String) return State; + -- Inverse of Image on States + +private + + N : constant := 624; + -- The number of 32-bit integers in the shift register + + M : constant := 397; + -- Feedback distance from the current position + + subtype State_Val is Interfaces.Unsigned_32; + type State is array (0 .. N - 1) of State_Val; + + type Writable_Access (Self : access Generator) is limited null record; + -- Auxiliary type to make Generator a self-referential type + + type Generator is limited record + Writable : Writable_Access (Generator'Access); + -- This self reference allows functions to modify Generator arguments + + S : State := (others => 0); + -- The shift register, a circular buffer + + I : Integer := N; + -- Current starting position in shift register S (N means uninitialized) + -- We should avoid using the identifier I here ??? + end record; + +end System.Random_Numbers; |