1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME COMPONENTS --
5 -- S Y S T E M . F L O A T _ C O N T R O L --
9 -- Copyright (C) 2000-2011, AdaCore --
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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 -- Control functions for floating-point unit
34 package System.Float_Control is
37 -- Reset the floating-point processor to the default state needed to get
38 -- correct Ada semantics for the target. Some third party tools change
39 -- the settings for the floating-point processor. Reset can be called
40 -- to reset the floating-point processor into the mode required by GNAT
41 -- for correct operation. Use this call after a call to foreign code if
42 -- you suspect incorrect floating-point operation after the call.
44 -- For example under Windows NT some system DLL calls change the default
45 -- FPU arithmetic to 64 bit precision mode. However, since in Ada 95 it
46 -- is required to provide full access to the floating-point types of the
47 -- architecture, GNAT requires full 80-bit precision mode, and Reset makes
48 -- sure this mode is established.
50 -- Similarly on the PPC processor, it is important that overflow and
51 -- underflow exceptions be disabled.
53 -- The call to Reset simply has no effect if the target environment
54 -- does not give rise to such concerns.
57 pragma Import (C, Reset, "__gnat_init_float");
59 end System.Float_Control;