1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME COMPONENTS -- 4-- -- 5-- S Y S T E M . E X N _ I N T -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2018, 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 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. -- 17-- -- 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. -- 21-- -- 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/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32package body System.Exn_Int is 33 34 ----------------- 35 -- Exn_Integer -- 36 ----------------- 37 38 function Exn_Integer (Left : Integer; Right : Natural) return Integer is 39 pragma Suppress (Division_Check); 40 pragma Suppress (Overflow_Check); 41 42 Result : Integer := 1; 43 Factor : Integer := Left; 44 Exp : Natural := Right; 45 46 begin 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. 50 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. 54 55 if Exp /= 0 then 56 loop 57 if Exp rem 2 /= 0 then 58 Result := Result * Factor; 59 end if; 60 61 Exp := Exp / 2; 62 exit when Exp = 0; 63 Factor := Factor * Factor; 64 end loop; 65 end if; 66 67 return Result; 68 end Exn_Integer; 69 70end System.Exn_Int; 71