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   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                    G N A T . F L O A T _ C O N T R O L                   --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --              Copyright (C) 2000 Ada Core Technologies, 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,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, 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 ------------------------------------------------------------------------------
  33
  34 --  Control functions for floating-point unit
  35
  36 package GNAT.Float_Control is
  37
  38    procedure Reset;
  39    --  Reset the floating-point processor to the default state needed to get
  40    --  correct Ada semantics for the target. Some third party tools change
  41    --  the settings for the floating-point processor. Reset can be called
  42    --  to reset the floating-point processor into the mode required by GNAT
  43    --  for correct operation. Use this call after a call to foreign code if
  44    --  you suspect incorrect floating-point operation after the call.
  45    --
  46    --  For example under Windows NT some system DLL calls change the default
  47    --  FPU arithmetic to 64 bit precision mode. However, since in Ada 95 it
  48    --  is required to provide full access to the floating-point types of the
  49    --  architecture, GNAT requires full 80-bit precision mode, and Reset makes
  50    --  sure this mode is established.
  51    --
  52    --  Similarly on the PPC processor, it is important that overflow and
  53    --  underflow exceptions be disabled.
  54    --
  55    --  The call to Reset simply has no effect if the target environment
  56    --  does not give rise to such concerns.
  57
  58 private
  59    pragma Import (C, Reset, "__gnat_init_float");
  60
  61 end GNAT.Float_Control;