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Diffstat (limited to 'gcc/ada/s-explli.adb')
| -rw-r--r-- | gcc/ada/s-explli.adb | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/gcc/ada/s-explli.adb b/gcc/ada/s-explli.adb new file mode 100644 index 00000000000..15eb0dfa611 --- /dev/null +++ b/gcc/ada/s-explli.adb @@ -0,0 +1,85 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT RUNTIME COMPONENTS -- +-- -- +-- S Y S T E M . E X P L L I -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2003 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 2, 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. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNAT; see file COPYING. If not, write -- +-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- +-- MA 02111-1307, USA. -- +-- -- +-- As a special exception, if other files instantiate generics from this -- +-- unit, or you link this unit with other files to produce an executable, -- +-- this unit does not by itself cause the resulting executable to be -- +-- covered by the GNU General Public License. This exception does not -- +-- however invalidate any other reasons why the executable file might be -- +-- covered by the GNU Public License. -- +-- -- +-- 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_LLI is + + --------------------------- + -- Exp_Long_Long_Integer -- + --------------------------- + + -- Note that negative exponents get a constraint error because the + -- subtype of the Right argument (the exponent) is Natural. + + function Exp_Long_Long_Integer + (Left : Long_Long_Integer; + Right : Natural) + return Long_Long_Integer + is + Result : Long_Long_Integer := 1; + Factor : Long_Long_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_Long_Long_Integer; + +end System.Exp_LLI; |