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   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                 S Y S T E M . F L O A T _ C O N T R O L                  --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 2000-2011, AdaCore                     --
  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 --  Control functions for floating-point unit
  33
  34 package System.Float_Control is
  35    pragma Pure;
  36    --  This is not fully correct, but this unit is with-ed by pure units
  37    --  (eg s-imgrea).
  38
  39    procedure Reset;
  40    pragma Inline (Reset);
  41    --  Reset the floating-point processor to the default state needed to get
  42    --  correct Ada semantics for the target. Some third party tools change
  43    --  the settings for the floating-point processor. Reset can be called
  44    --  to reset the floating-point processor into the mode required by GNAT
  45    --  for correct operation. Use this call after a call to foreign code if
  46    --  you suspect incorrect floating-point operation after the call.
  47    --
  48    --  For example under Windows NT some system DLL calls change the default
  49    --  FPU arithmetic to 64 bit precision mode. However, since in Ada 95 it
  50    --  is required to provide full access to the floating-point types of the
  51    --  architecture, GNAT requires full 80-bit precision mode, and Reset makes
  52    --  sure this mode is established.
  53    --
  54    --  Similarly on the PPC processor, it is important that overflow and
  55    --  underflow exceptions be disabled.
  56    --
  57    --  The call to Reset simply has no effect if the target environment
  58    --  does not give rise to such concerns.
  59 end System.Float_Control;