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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- S Y S T E M . E X N _ L L I --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2005 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 2, 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
21 -- --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
28 -- --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
31 -- --
32 ------------------------------------------------------------------------------
34 package body System.Exn_LLI is
36 ---------------------------
37 -- Exn_Long_Long_Integer --
38 ---------------------------
40 function Exn_Long_Long_Integer
41 (Left : Long_Long_Integer;
42 Right : Natural)
43 return Long_Long_Integer
45 pragma Suppress (Division_Check);
46 pragma Suppress (Overflow_Check);
48 Result : Long_Long_Integer := 1;
49 Factor : Long_Long_Integer := Left;
50 Exp : Natural := Right;
52 begin
53 -- We use the standard logarithmic approach, Exp gets shifted right
54 -- testing successive low order bits and Factor is the value of the
55 -- base raised to the next power of 2.
57 -- Note: it is not worth special casing base values -1, 0, +1 since
58 -- the expander does this when the base is a literal, and other cases
59 -- will be extremely rare.
61 if Exp /= 0 then
62 loop
63 if Exp rem 2 /= 0 then
64 Result := Result * Factor;
65 end if;
67 Exp := Exp / 2;
68 exit when Exp = 0;
69 Factor := Factor * Factor;
70 end loop;
71 end if;
73 return Result;
74 end Exn_Long_Long_Integer;
76 end System.Exn_LLI;