File : s-flocon.ads
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 -- --
19 -- --
20 -- --
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;