git://gcc.gnu.org / gcc.git / blame
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|---|---|---|
| cacbc350 RK |
1 | ------------------------------------------------------------------------------ |
| 2 | -- -- | |
| 3 | -- GNAT RUNTIME COMPONENTS -- | |
| 4 | -- -- | |
| 5 | -- S Y S T E M . X P _ B M L -- | |
| 6 | -- -- | |
| 7 | -- B o d y -- | |
| 8 | -- -- | |
| cacbc350 RK |
9 | -- Copyright (C) 1992,1993,1994 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 2, 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. See the GNU General Public License -- | |
| 17 | -- for more details. You should have received a copy of the GNU General -- | |
| 18 | -- Public License distributed with GNAT; see file COPYING. If not, write -- | |
| 19 | -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- | |
| 20 | -- MA 02111-1307, USA. -- | |
| 21 | -- -- | |
| 22 | -- As a special exception, if other files instantiate generics from this -- | |
| 23 | -- unit, or you link this unit with other files to produce an executable, -- | |
| 24 | -- this unit does not by itself cause the resulting executable to be -- | |
| 25 | -- covered by the GNU General Public License. This exception does not -- | |
| 26 | -- however invalidate any other reasons why the executable file might be -- | |
| 27 | -- covered by the GNU Public License. -- | |
| 28 | -- -- | |
| 29 | -- GNAT was originally developed by the GNAT team at New York University. -- | |
| 71ff80dc | 30 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| cacbc350 RK |
31 | -- -- |
| 32 | ------------------------------------------------------------------------------ | |
| 33 | ||
| 34 | with System.Unsigned_Types; use System.Unsigned_Types; | |
| 35 | ||
| 36 | package body System.Exp_LLU is | |
| 37 | ||
| 38 | ---------------------------- | |
| 39 | -- Exp_Long_Long_Unsigned -- | |
| 40 | ---------------------------- | |
| 41 | ||
| 42 | function Exp_Long_Long_Unsigned | |
| 43 | (Left : Long_Long_Unsigned; | |
| 44 | Right : Natural) | |
| 45 | return Long_Long_Unsigned | |
| 46 | is | |
| 47 | Result : Long_Long_Unsigned := 1; | |
| 48 | Factor : Long_Long_Unsigned := Left; | |
| 49 | Exp : Natural := Right; | |
| 50 | ||
| 51 | begin | |
| 52 | -- We use the standard logarithmic approach, Exp gets shifted right | |
| 53 | -- testing successive low order bits and Factor is the value of the | |
| 54 | -- base raised to the next power of 2. | |
| 55 | ||
| 56 | -- Note: it is not worth special casing the cases of base values -1,0,+1 | |
| 57 | -- since the expander does this when the base is a literal, and other | |
| 58 | -- cases will be extremely rare. | |
| 59 | ||
| 60 | if Exp /= 0 then | |
| 61 | loop | |
| 62 | if Exp rem 2 /= 0 then | |
| 63 | Result := Result * Factor; | |
| 64 | end if; | |
| 65 | ||
| 66 | Exp := Exp / 2; | |
| 67 | exit when Exp = 0; | |
| 68 | Factor := Factor * Factor; | |
| 69 | end loop; | |
| 70 | end if; | |
| 71 | ||
| 72 | return Result; | |
| 73 | ||
| 74 | end Exp_Long_Long_Unsigned; | |
| 75 | ||
| 76 | end System.Exp_LLU; |