File : s-addope.ads
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S Y S T E M . A D D R E S S _ O P E R A T I O N S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2004-2013, Free Software Foundation, 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 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 -- This package provides arithmetic and logical operations on type Address.
33 -- It is intended for use by other packages in the System hierarchy. For
34 -- applications requiring this capability, see System.Storage_Elements or
35 -- the operations introduced in System.Aux_DEC;
36
37 -- The reason we need this package is that arithmetic operations may not
38 -- be available in the case where type Address is non-private and the
39 -- operations have been made abstract in the spec of System (to avoid
40 -- inappropriate use by applications programs). In addition, the logical
41 -- operations may not be available if type Address is a signed integer.
42
43 pragma Compiler_Unit_Warning;
44
45 package System.Address_Operations is
46 pragma Pure;
47
48 -- The semantics of the arithmetic operations are those that apply to
49 -- a modular type with the same length as Address, i.e. they provide
50 -- twos complement wrap around arithmetic treating the address value
51 -- as an unsigned value, with no overflow checking.
52
53 -- Note that we do not use the infix names for these operations to
54 -- avoid problems with ambiguities coming from declarations in package
55 -- Standard (which may or may not be visible depending on the exact
56 -- form of the declaration of type System.Address).
57
58 -- For addition, subtraction, and multiplication, the effect of overflow
59 -- is 2's complement wrapping (as though the type Address were unsigned).
60
61 -- For division and modulus operations, the caller is responsible for
62 -- ensuring that the Right argument is non-zero, and the effect of the
63 -- call is not specified if a zero argument is passed.
64
65 function AddA (Left, Right : Address) return Address;
66 function SubA (Left, Right : Address) return Address;
67 function MulA (Left, Right : Address) return Address;
68 function DivA (Left, Right : Address) return Address;
69 function ModA (Left, Right : Address) return Address;
70
71 -- The semantics of the logical operations are those that apply to
72 -- a modular type with the same length as Address, i.e. they provide
73 -- bit-wise operations on all bits of the value (including the sign
74 -- bit if Address is a signed integer type).
75
76 function AndA (Left, Right : Address) return Address;
77 function OrA (Left, Right : Address) return Address;
78
79 pragma Inline_Always (AddA);
80 pragma Inline_Always (SubA);
81 pragma Inline_Always (MulA);
82 pragma Inline_Always (DivA);
83 pragma Inline_Always (ModA);
84 pragma Inline_Always (AndA);
85 pragma Inline_Always (OrA);
86
87 end System.Address_Operations;