1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . E X N _ I N T --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 package body System.Exn_Int is
38 function Exn_Integer (Left : Integer; Right : Natural) return Integer is
39 pragma Suppress (Division_Check);
40 pragma Suppress (Overflow_Check);
42 Result : Integer := 1;
43 Factor : Integer := Left;
44 Exp : Natural := Right;
47 -- We use the standard logarithmic approach, Exp gets shifted right
48 -- testing successive low order bits and Factor is the value of the
49 -- base raised to the next power of 2.
51 -- Note: it is not worth special casing base values -1, 0, +1 since
52 -- the expander does this when the base is a literal, and other cases
53 -- will be extremely rare.
57 if Exp rem 2 /= 0 then
58 Result := Result * Factor;
63 Factor := Factor * Factor;