------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                         S Y S T E M . M E M O R Y                        --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 2001-2010, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
--                                                                          --
--                                                                          --
--                                                                          --
--                                                                          --
--                                                                          --
-- You should have received a copy of the GNU General Public License and    --
-- a copy of the GCC Runtime Library Exception along with this program;     --
-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This is the simplified implementation of this package, for use with a
--  configurable run-time library.

--  This implementation assumes that the underlying malloc/free/realloc
--  implementation is *not* thread safe, and thus, explicit lock is required.

with Ada.Exceptions;

with System.Soft_Links;

package body System.Memory is

   use Ada.Exceptions;
   use System.Soft_Links;

   function c_malloc (Size : size_t) return System.Address;
   pragma Import (C, c_malloc, "malloc");

   procedure c_free (Ptr : System.Address);
   pragma Import (C, c_free, "free");

   function c_realloc
     (Ptr : System.Address; Size : size_t) return System.Address;
   pragma Import (C, c_realloc, "realloc");

   -----------
   -- Alloc --
   -----------

   function Alloc (Size : size_t) return System.Address is
      Result      : System.Address;
      Actual_Size : size_t := Size;

   begin
      if Size = size_t'Last then
         Raise_Exception (Storage_Error'Identity, "object too large");
      end if;

      --  Change size from zero to non-zero. We still want a proper pointer
      --  for the zero case because pointers to zero length objects have to
      --  be distinct, but we can't just go ahead and allocate zero bytes,
      --  since some malloc's return zero for a zero argument.

      if Size = 0 then
         Actual_Size := 1;
      end if;

      Lock_Task.all;

      Result := c_malloc (Actual_Size);

      Unlock_Task.all;

      if Result = System.Null_Address then
         Raise_Exception (Storage_Error'Identity, "heap exhausted");
      end if;

      return Result;
   end Alloc;

   ----------
   -- Free --
   ----------

   procedure Free (Ptr : System.Address) is
   begin
      Lock_Task.all;

      c_free (Ptr);

      Unlock_Task.all;
   end Free;

   -------------
   -- Realloc --
   -------------

   function Realloc
     (Ptr  : System.Address;
      Size : size_t)
     return System.Address
   is
      Result : System.Address;

   begin
      if Size = size_t'Last then
         Raise_Exception (Storage_Error'Identity, "object too large");
      end if;

      Lock_Task.all;

      Result := c_realloc (Ptr, Size);

      Unlock_Task.all;

      if Result = System.Null_Address then
         Raise_Exception (Storage_Error'Identity, "heap exhausted");
      end if;

      return Result;
   end Realloc;

end System.Memory;