108 lines
5.5 KiB
Ada
108 lines
5.5 KiB
Ada
------------------------------------------------------------------------------
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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) 2001-2013, 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 3, 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. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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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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pragma Compiler_Unit_Warning;
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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) 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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