Mercurial > hg > CbC > CbC_gcc
comparison gcc/ada/libgnat/s-expuns.adb @ 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 _ U N S -- | |
| 6 -- -- | |
| 7 -- B o d y -- | |
| 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 with System.Unsigned_Types; use System.Unsigned_Types; | |
| 33 | |
| 34 package body System.Exp_Uns is | |
| 35 | |
| 36 ------------------ | |
| 37 -- Exp_Unsigned -- | |
| 38 ------------------ | |
| 39 | |
| 40 function Exp_Unsigned | |
| 41 (Left : Unsigned; | |
| 42 Right : Natural) | |
| 43 return Unsigned | |
| 44 is | |
| 45 Result : Unsigned := 1; | |
| 46 Factor : Unsigned := Left; | |
| 47 Exp : Natural := Right; | |
| 48 | |
| 49 begin | |
| 50 -- We use the standard logarithmic approach, Exp gets shifted right | |
| 51 -- testing successive low order bits and Factor is the value of the | |
| 52 -- base raised to the next power of 2. | |
| 53 | |
| 54 -- Note: it is not worth special casing the cases of base values -1,0,+1 | |
| 55 -- since the expander does this when the base is a literal, and other | |
| 56 -- cases will be extremely rare. | |
| 57 | |
| 58 if Exp /= 0 then | |
| 59 loop | |
| 60 if Exp rem 2 /= 0 then | |
| 61 Result := Result * Factor; | |
| 62 end if; | |
| 63 | |
| 64 Exp := Exp / 2; | |
| 65 exit when Exp = 0; | |
| 66 Factor := Factor * Factor; | |
| 67 end loop; | |
| 68 end if; | |
| 69 | |
| 70 return Result; | |
| 71 end Exp_Unsigned; | |
| 72 | |
| 73 end System.Exp_Uns; |