1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                         S Y S T E M . M E M O R Y                        --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 2001-2003 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 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--  This is the default implementation of this package.
35
36--  This implementation assumes that the underlying malloc/free/realloc
37--  implementation is thread safe, and thus, no additional lock is required.
38--  Note that we still need to defer abortion because on most systems,
39--  an asynchronous signal (as used for implementing asynchronous abortion
40--  of task) cannot safely be handled while malloc is executing.
41
42--  If you are not using Ada constructs containing the "abort" keyword,
43--  then you can remove the calls to Abort_Defer.all and Abort_Undefer.all
44--  from this unit.
45
46with Ada.Exceptions;
47with System.Soft_Links;
48with System.Parameters;
49with System.CRTL;
50
51package body System.Memory is
52
53   use Ada.Exceptions;
54   use System.Soft_Links;
55
56   function c_malloc (Size : System.CRTL.size_t) return System.Address
57    renames System.CRTL.malloc;
58
59   procedure c_free (Ptr : System.Address)
60     renames System.CRTL.free;
61
62   function c_realloc
63     (Ptr : System.Address; Size : System.CRTL.size_t) return System.Address
64     renames System.CRTL.realloc;
65
66   -----------
67   -- Alloc --
68   -----------
69
70   function Alloc (Size : size_t) return System.Address is
71      Result      : System.Address;
72      Actual_Size : size_t := Size;
73
74   begin
75      if Size = size_t'Last then
76         Raise_Exception (Storage_Error'Identity, "object too large");
77      end if;
78
79      --  Change size from zero to non-zero. We still want a proper pointer
80      --  for the zero case because pointers to zero length objects have to
81      --  be distinct, but we can't just go ahead and allocate zero bytes,
82      --  since some malloc's return zero for a zero argument.
83
84      if Size = 0 then
85         Actual_Size := 1;
86      end if;
87
88      if Parameters.No_Abort then
89         Result := c_malloc (System.CRTL.size_t (Actual_Size));
90      else
91         Abort_Defer.all;
92         Result := c_malloc (System.CRTL.size_t (Actual_Size));
93         Abort_Undefer.all;
94      end if;
95
96      if Result = System.Null_Address then
97         Raise_Exception (Storage_Error'Identity, "heap exhausted");
98      end if;
99
100      return Result;
101   end Alloc;
102
103   ----------
104   -- Free --
105   ----------
106
107   procedure Free (Ptr : System.Address) is
108   begin
109      if Parameters.No_Abort then
110         c_free (Ptr);
111      else
112         Abort_Defer.all;
113         c_free (Ptr);
114         Abort_Undefer.all;
115      end if;
116   end Free;
117
118   -------------
119   -- Realloc --
120   -------------
121
122   function Realloc
123     (Ptr  : System.Address;
124      Size : size_t)
125      return System.Address
126   is
127      Result      : System.Address;
128      Actual_Size : constant size_t := Size;
129
130   begin
131      if Size = size_t'Last then
132         Raise_Exception (Storage_Error'Identity, "object too large");
133      end if;
134
135      if Parameters.No_Abort then
136         Result := c_realloc (Ptr, System.CRTL.size_t (Actual_Size));
137      else
138         Abort_Defer.all;
139         Result := c_realloc (Ptr, System.CRTL.size_t (Actual_Size));
140         Abort_Undefer.all;
141      end if;
142
143      if Result = System.Null_Address then
144         Raise_Exception (Storage_Error'Identity, "heap exhausted");
145      end if;
146
147      return Result;
148   end Realloc;
149
150end System.Memory;
151