1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--               S Y S T E M . S T O R A G E _ E L E M E N T S              --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2002-2021, Free Software Foundation, Inc.         --
10--                                                                          --
11-- This specification is derived from the Ada Reference Manual for use with --
12-- GNAT. The copyright notice above, and the license provisions that follow --
13-- apply solely to the implementation dependent sections of this file.      --
14--                                                                          --
15-- GNAT is free software;  you can  redistribute it  and/or modify it under --
16-- terms of the  GNU General Public License as published  by the Free Soft- --
17-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
18-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
19-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
20-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
21--                                                                          --
22-- As a special exception under Section 7 of GPL version 3, you are granted --
23-- additional permissions described in the GCC Runtime Library Exception,   --
24-- version 3.1, as published by the Free Software Foundation.               --
25--                                                                          --
26-- You should have received a copy of the GNU General Public License and    --
27-- a copy of the GCC Runtime Library Exception along with this program;     --
28-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
29-- <http://www.gnu.org/licenses/>.                                          --
30--                                                                          --
31-- GNAT was originally developed  by the GNAT team at  New York University. --
32-- Extensive contributions were provided by Ada Core Technologies Inc.      --
33--                                                                          --
34------------------------------------------------------------------------------
35
36--  Warning: declarations in this package are ambiguous with respect to the
37--  extra declarations that can be introduced into System using Extend_System.
38--  It is a good idea to avoid use clauses for this package.
39
40pragma Compiler_Unit_Warning;
41
42package System.Storage_Elements is
43   pragma Pure;
44   --  Note that we take advantage of the implementation permission to make
45   --  this unit Pure instead of Preelaborable; see RM 13.7.1(15). In Ada 2005,
46   --  this is Pure in any case (AI-362).
47
48   --  We also add the pragma Pure_Function to the operations in this package,
49   --  because otherwise functions with parameters derived from Address are
50   --  treated as non-pure by the back-end (see exp_ch6.adb). This is because
51   --  in many cases such a parameter is used to hide read/out access to
52   --  objects, and it would be unsafe to treat such functions as pure.
53
54   type Storage_Offset is range
55     -(2 ** (Integer'(Standard'Address_Size) - 1)) ..
56     +(2 ** (Integer'(Standard'Address_Size) - 1)) - Long_Long_Integer'(1);
57   --  Note: the reason for the Long_Long_Integer qualification here is to
58   --  avoid a bogus ambiguity when this unit is analyzed in an rtsfind
59   --  context.
60
61   subtype Storage_Count is Storage_Offset range 0 .. Storage_Offset'Last;
62
63   type Storage_Element is mod 2 ** Storage_Unit;
64   for Storage_Element'Size use Storage_Unit;
65
66   pragma Universal_Aliasing (Storage_Element);
67   --  This type is used by the expander to implement aggregate copy
68
69   type Storage_Array is
70     array (Storage_Offset range <>) of aliased Storage_Element;
71   for Storage_Array'Component_Size use Storage_Unit;
72
73   --  Address arithmetic
74
75   function "+" (Left : Address; Right : Storage_Offset) return Address;
76   pragma Convention (Intrinsic, "+");
77   pragma Inline_Always ("+");
78   pragma Pure_Function ("+");
79
80   function "+" (Left : Storage_Offset; Right : Address) return Address;
81   pragma Convention (Intrinsic, "+");
82   pragma Inline_Always ("+");
83   pragma Pure_Function ("+");
84
85   function "-" (Left : Address; Right : Storage_Offset) return Address;
86   pragma Convention (Intrinsic, "-");
87   pragma Inline_Always ("-");
88   pragma Pure_Function ("-");
89
90   function "-" (Left, Right : Address) return Storage_Offset;
91   pragma Convention (Intrinsic, "-");
92   pragma Inline_Always ("-");
93   pragma Pure_Function ("-");
94
95   function "mod"
96     (Left  : Address;
97      Right : Storage_Offset) return  Storage_Offset;
98   pragma Convention (Intrinsic, "mod");
99   pragma Inline_Always ("mod");
100   pragma Pure_Function ("mod");
101
102   --  Conversion to/from integers
103
104   type Integer_Address is mod Memory_Size;
105
106   function To_Address (Value : Integer_Address) return Address;
107   pragma Convention (Intrinsic, To_Address);
108   pragma Inline_Always (To_Address);
109   pragma Pure_Function (To_Address);
110
111   function To_Integer (Value : Address) return Integer_Address;
112   pragma Convention (Intrinsic, To_Integer);
113   pragma Inline_Always (To_Integer);
114   pragma Pure_Function (To_Integer);
115
116end System.Storage_Elements;
117