1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                  S Y S T E M . P O W T E N _ T A B L E                   --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2009 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
32--  This package provides a powers of ten table used for real conversions
33
34package System.Powten_Table is
35   pragma Pure;
36
37   Maxpow : constant := 22;
38   --  The number of entries in this table is chosen to include powers of ten
39   --  that are exactly representable with long_long_float. Assuming that on
40   --  all targets we have 53 bits of mantissa for the type, the upper bound is
41   --  given by 53/(log 5). If the scaling factor for a string is greater than
42   --  Maxpow, it can be obtained by several multiplications, which is less
43   --  efficient than with a bigger table, but avoids anomalies at end points.
44
45   Powten : constant array (0 .. Maxpow) of Long_Long_Float :=
46      (00 => 1.0E+00,
47       01 => 1.0E+01,
48       02 => 1.0E+02,
49       03 => 1.0E+03,
50       04 => 1.0E+04,
51       05 => 1.0E+05,
52       06 => 1.0E+06,
53       07 => 1.0E+07,
54       08 => 1.0E+08,
55       09 => 1.0E+09,
56       10 => 1.0E+10,
57       11 => 1.0E+11,
58       12 => 1.0E+12,
59       13 => 1.0E+13,
60       14 => 1.0E+14,
61       15 => 1.0E+15,
62       16 => 1.0E+16,
63       17 => 1.0E+17,
64       18 => 1.0E+18,
65       19 => 1.0E+19,
66       20 => 1.0E+20,
67       21 => 1.0E+21,
68       22 => 1.0E+22);
69
70end System.Powten_Table;
71