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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . M E M O R Y --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2001-2003 Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
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-- Boston, MA 02110-1301, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides the low level memory allocation/deallocation
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-- mechanisms used by GNAT.
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-- To provide an alternate implementation, simply recompile the modified
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-- body of this package with gnatmake -u -a -g s-memory.adb and make sure
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-- that the ali and object files for this unit are found in the object
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-- search path.
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-- This unit may be used directly from an application program by providing
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-- an appropriate WITH, and the interface can be expected to remain stable.
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package System.Memory is
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pragma Elaborate_Body;
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type size_t is mod 2 ** Standard'Address_Size;
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-- Note: the reason we redefine this here instead of using the
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-- definition in Interfaces.C is that we do not want to drag in
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-- all of Interfaces.C just because System.Memory is used.
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function Alloc (Size : size_t) return System.Address;
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-- This is the low level allocation routine. Given a size in storage
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-- units, it returns the address of a maximally aligned block of
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-- memory. The implementation of this routine is guaranteed to be
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-- task safe, and also aborts are deferred if necessary.
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--
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-- If size_t is set to size_t'Last on entry, then a Storage_Error
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-- exception is raised with a message "object too large".
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--
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-- If size_t is set to zero on entry, then a minimal (but non-zero)
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-- size block is allocated.
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--
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-- Note: this is roughly equivalent to the standard C malloc call
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-- with the additional semantics as described above.
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procedure Free (Ptr : System.Address);
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-- This is the low level free routine. It frees a block previously
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-- allocated with a call to Alloc. As in the case of Alloc, this
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-- call is guaranteed task safe, and aborts are deferred.
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--
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-- Note: this is roughly equivalent to the standard C free call
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-- with the additional semantics as described above.
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function Realloc
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(Ptr : System.Address;
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Size : size_t)
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return System.Address;
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-- This is the low level reallocation routine. It takes an existing
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-- block address returned by a previous call to Alloc or Realloc,
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-- and reallocates the block. The size can either be increased or
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-- decreased. If possible the reallocation is done in place, so that
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-- the returned result is the same as the value of Ptr on entry.
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-- However, it may be necessary to relocate the block to another
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-- address, in which case the information is copied to the new
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-- block, and the old block is freed. The implementation of this
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-- routine is guaranteed to be task safe, and also aborts are
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-- deferred as necessary.
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--
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-- If size_t is set to size_t'Last on entry, then a Storage_Error
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-- exception is raised with a message "object too large".
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--
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-- If size_t is set to zero on entry, then a minimal (but non-zero)
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-- size block is allocated.
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--
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-- Note: this is roughly equivalent to the standard C realloc call
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-- with the additional semantics as described above.
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private
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-- The following names are used from the generated compiler code
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pragma Export (C, Alloc, "__gnat_malloc");
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pragma Export (C, Free, "__gnat_free");
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pragma Export (C, Realloc, "__gnat_realloc");
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end System.Memory;
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