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[/] [openrisc/] [tags/] [gnu-src/] [gcc-4.5.1/] [gcc-4.5.1-or32-1.0rc1/] [gcc/] [ada/] [s-expint.adb] - Rev 338
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------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- S Y S T E M . E X P I N T -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2009 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. -- -- -- ------------------------------------------------------------------------------ package body System.Exp_Int is ----------------- -- Exp_Integer -- ----------------- -- Note that negative exponents get a constraint error because the -- subtype of the Right argument (the exponent) is Natural. function Exp_Integer (Left : Integer; Right : Natural) return Integer is Result : Integer := 1; Factor : Integer := Left; Exp : Natural := Right; begin -- We use the standard logarithmic approach, Exp gets shifted right -- testing successive low order bits and Factor is the value of the -- base raised to the next power of 2. -- Note: it is not worth special casing base values -1, 0, +1 since -- the expander does this when the base is a literal, and other cases -- will be extremely rare. if Exp /= 0 then loop if Exp rem 2 /= 0 then declare pragma Unsuppress (All_Checks); begin Result := Result * Factor; end; end if; Exp := Exp / 2; exit when Exp = 0; declare pragma Unsuppress (All_Checks); begin Factor := Factor * Factor; end; end loop; end if; return Result; end Exp_Integer; end System.Exp_Int;