71 lines
3.5 KiB
Ada
71 lines
3.5 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S Y S T E M . P O W T E N _ T A B L E --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides a powers of ten table used for real conversions
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package System.Powten_Table is
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pragma Pure;
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Maxpow : constant := 22;
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-- The number of entries in this table is chosen to include powers of ten
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-- that are exactly representable with long_long_float. Assuming that on
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-- all targets we have 53 bits of mantissa for the type, the upper bound is
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-- given by 53/(log 5). If the scaling factor for a string is greater than
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-- Maxpow, it can be obtained by several multiplications, which is less
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-- efficient than with a bigger table, but avoids anomalies at end points.
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Powten : constant array (0 .. Maxpow) of Long_Long_Float :=
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(00 => 1.0E+00,
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01 => 1.0E+01,
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02 => 1.0E+02,
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03 => 1.0E+03,
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04 => 1.0E+04,
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05 => 1.0E+05,
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06 => 1.0E+06,
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07 => 1.0E+07,
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08 => 1.0E+08,
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09 => 1.0E+09,
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10 => 1.0E+10,
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11 => 1.0E+11,
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12 => 1.0E+12,
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13 => 1.0E+13,
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14 => 1.0E+14,
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15 => 1.0E+15,
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16 => 1.0E+16,
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17 => 1.0E+17,
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18 => 1.0E+18,
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19 => 1.0E+19,
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20 => 1.0E+20,
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21 => 1.0E+21,
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22 => 1.0E+22);
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end System.Powten_Table;
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