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------------------------------------------------------------------------------
-- --
-- GNAT RUNTIME COMPONENTS --
-- --
-- S Y S T E M . X P _ B M L --
-- --
-- B o d y --
-- --
-- $Revision: 1.7 $ --
-- --
-- Copyright (C) 1992,1993,1994 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. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
with System.Unsigned_Types; use System.Unsigned_Types;
package body System.Exp_LLU is
----------------------------
-- Exp_Long_Long_Unsigned --
----------------------------
function Exp_Long_Long_Unsigned
(Left : Long_Long_Unsigned;
Right : Natural)
return Long_Long_Unsigned
is
Result : Long_Long_Unsigned := 1;
Factor : Long_Long_Unsigned := 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 the cases of 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
Result := Result * Factor;
end if;
Exp := Exp / 2;
exit when Exp = 0;
Factor := Factor * Factor;
end loop;
end if;
return Result;
end Exp_Long_Long_Unsigned;
end System.Exp_LLU;
|
