MemoryRegion.h revision 22add6ff3426df1a85089fe6a6e1597ee3b6f300 
1//===- MemoryRegion.h -----------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9#ifndef LD_MEMORY_REGION_H
10#define LD_MEMORY_REGION_H
11#ifdef ENABLE_UNITTEST
12#include <gtest.h>
13#endif
14
15#include <mcld/Config/Config.h>
16#include <mcld/ADT/Uncopyable.h>
17#include <mcld/Support/Allocators.h>
18#include <mcld/Support/Space.h>
19
20namespace mcld {
21
22class MemoryArea;
23
24/** \class MemoryRegion
25 *  \brief MemoryRegion is a range of virtual memory which is mapped onto a
26 *  range of files which is opened by MemoryArea.
27 *
28 *  MemoryArea maps a file onto virtual memory. Clients can get a range of
29 *  mapped memory space by requesting a MemoryRegion from MemoryArea, and
30 *  read/write the mapped file through the MemoryRegion.
31 *
32 *  When two different MemoryRegion may overlap memory space, race condition
33 *  may occurs. Clients must call MemoryRegion::sync() explicit to tell the
34 *  MemoryArea when to synchronize the virtual memory space with the mapped
35 *  file.
36 */
37class MemoryRegion : private Uncopyable
38{
39friend class Chunk<MemoryRegion, MCLD_REGION_CHUNK_SIZE>;
40friend class RegionFactory;
41friend class MemoryArea;
42
43public:
44  typedef Space::Address Address;
45  typedef Space::ConstAddress ConstAddress;
46
47private:
48  MemoryRegion();
49
50  MemoryRegion(const Address pVMAStart, size_t pSize);
51
52  ~MemoryRegion();
53
54  void setParent(Space& pSpace) { m_pParent = &pSpace; }
55
56public:
57  /// Create - To wrap a piece of memory and to create a new region.
58  /// This function wraps a piece of memory and to create a new region. Region
59  /// is just a wraper, it is not responsible for deallocate the given memory.
60  ///
61  /// @param pStart [in] The start address of a piece of memory
62  /// @param pSize  [in] The size of the given memory
63  static MemoryRegion* Create(void* pStart, size_t pSize);
64
65  /// Create - To wrap a piece of memory and to create a new region.
66  /// This function wraps a piece of memory and to create a new region. Region
67  /// is just a wraper, it is not responsible for deallocate the given memory.
68  ///
69  /// If a wrapped memory comes from a Space, then we say the space is the
70  /// parent of the region. pSpace is a memory counting container. It remembers
71  /// the number of regions in it. A space which has no region will be removed
72  /// quickly.
73  ///
74  /// The wrapped memory will be deallocated by Space when the space has no
75  /// region used it.
76  ///
77  /// @param pStart [in] The start address of a piece of memory
78  /// @param pSize  [in] The size of the given memory
79  /// @param pSpace [in] The parent space.
80  static MemoryRegion* Create(void* pStart, size_t pSize, Space& pSpace);
81
82  /// Destroy - To destroy the region
83  /// If the region has a parent space, it will be also remove from the space.
84  ///
85  /// @param pRegion [in, out] pRegion is set to NULL if the destruction is
86  /// success.
87  static void Destroy(MemoryRegion*& pRegion);
88
89  const Space* parent() const { return m_pParent; }
90  Space*       parent()       { return m_pParent; }
91
92  bool hasParent() const { return (NULL != m_pParent); }
93
94  ConstAddress start() const { return m_VMAStart; }
95  Address      start()       { return m_VMAStart; }
96
97  ConstAddress end() const { return m_VMAStart+m_Length; }
98  Address      end()       { return m_VMAStart+m_Length; }
99
100  size_t size() const { return m_Length; }
101
102  ConstAddress getBuffer(size_t pOffset = 0) const
103  { return m_VMAStart+pOffset; }
104
105  Address getBuffer(size_t pOffset = 0)
106  { return m_VMAStart+pOffset; }
107
108private:
109  Space* m_pParent;
110  Address m_VMAStart;
111  size_t m_Length;
112};
113
114} // namespace of mcld
115
116#endif
117
118