Mercurial > hg > CbC > CbC_gcc
comparison gcc/ada/libgnat/s-expmod.ads @ 111:04ced10e8804
gcc 7
| author | kono |
|---|---|
| date | Fri, 27 Oct 2017 22:46:09 +0900 |
| parents | |
| children | 84e7813d76e9 |
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| 68:561a7518be6b | 111:04ced10e8804 |
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| 1 ------------------------------------------------------------------------------ | |
| 2 -- -- | |
| 3 -- GNAT RUN-TIME COMPONENTS -- | |
| 4 -- -- | |
| 5 -- S Y S T E M . E X P _ M O D -- | |
| 6 -- -- | |
| 7 -- S p e c -- | |
| 8 -- -- | |
| 9 -- Copyright (C) 1992-2017, 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 -- This function performs exponentiation of a modular type with nonbinary | |
| 33 -- modulus values. Arithmetic is done in Long_Long_Unsigned, with explicit | |
| 34 -- accounting for the modulus value which is passed as the second argument. | |
| 35 -- Note that 1 is a binary modulus (2**0), so the compiler should not (and | |
| 36 -- will not) call this function with Modulus equal to 1. | |
| 37 | |
| 38 with System.Unsigned_Types; | |
| 39 | |
| 40 package System.Exp_Mod is | |
| 41 pragma Pure; | |
| 42 use type System.Unsigned_Types.Unsigned; | |
| 43 | |
| 44 subtype Power_Of_2 is System.Unsigned_Types.Unsigned with | |
| 45 Dynamic_Predicate => | |
| 46 Power_Of_2 /= 0 and then (Power_Of_2 and (Power_Of_2 - 1)) = 0; | |
| 47 | |
| 48 function Exp_Modular | |
| 49 (Left : System.Unsigned_Types.Unsigned; | |
| 50 Modulus : System.Unsigned_Types.Unsigned; | |
| 51 Right : Natural) return System.Unsigned_Types.Unsigned | |
| 52 with | |
| 53 Pre => Modulus /= 0 and then Modulus not in Power_Of_2, | |
| 54 Post => Exp_Modular'Result = Left ** Right mod Modulus; | |
| 55 | |
| 56 end System.Exp_Mod; |