Qt 4.8
qdeclarativejsmemorypool_p.h
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41 
42 #ifndef QDECLARATIVEJSMEMORYPOOL_P_H
43 #define QDECLARATIVEJSMEMORYPOOL_P_H
44 
45 //
46 // W A R N I N G
47 // -------------
48 //
49 // This file is not part of the Qt API. It exists purely as an
50 // implementation detail. This header file may change from version to
51 // version without notice, or even be removed.
52 //
53 // We mean it.
54 //
55 
56 #include "private/qdeclarativejsglobal_p.h"
57 
58 #include <QtCore/qglobal.h>
59 #include <QtCore/qshareddata.h>
60 
61 #include <string.h>
62 
63 QT_QML_BEGIN_NAMESPACE
64 
65 namespace QDeclarativeJS {
66 
67 class QML_PARSER_EXPORT MemoryPool : public QSharedData
68 {
69 public:
70  enum { maxBlockCount = -1 };
71  enum { defaultBlockSize = 1 << 12 };
72 
73  MemoryPool() {
74  m_blockIndex = maxBlockCount;
75  m_currentIndex = 0;
76  m_storage = 0;
77  m_currentBlock = 0;
78  m_currentBlockSize = 0;
79  }
80 
81  virtual ~MemoryPool() {
82  for (int index = 0; index < m_blockIndex + 1; ++index)
83  qFree(m_storage[index]);
84 
85  qFree(m_storage);
86  }
87 
88  char *allocate(int bytes) {
89  bytes += (8 - bytes) & 7; // ensure multiple of 8 bytes (maintain alignment)
90  if (m_currentBlock == 0 || m_currentBlockSize < m_currentIndex + bytes) {
91  ++m_blockIndex;
92  m_currentBlockSize = defaultBlockSize << m_blockIndex;
93 
94  m_storage = reinterpret_cast<char**>(qRealloc(m_storage, sizeof(char*) * (1 + m_blockIndex)));
95  m_currentBlock = m_storage[m_blockIndex] = reinterpret_cast<char*>(qMalloc(m_currentBlockSize));
96  ::memset(m_currentBlock, 0, m_currentBlockSize);
97 
98  m_currentIndex = (8 - quintptr(m_currentBlock)) & 7; // ensure first chunk is 64-bit aligned
99  Q_ASSERT(m_currentIndex + bytes <= m_currentBlockSize);
100  }
101 
102  char *p = reinterpret_cast<char *>
103  (m_currentBlock + m_currentIndex);
104 
105  m_currentIndex += bytes;
106 
107  return p;
108  }
109 
110  int bytesAllocated() const {
111  int bytes = 0;
112  for (int index = 0; index < m_blockIndex; ++index)
113  bytes += (defaultBlockSize << index);
114  bytes += m_currentIndex;
115  return bytes;
116  }
117 
118 private:
119  int m_blockIndex;
120  int m_currentIndex;
121  char *m_currentBlock;
122  int m_currentBlockSize;
123  char **m_storage;
124 
125 private:
126  Q_DISABLE_COPY(MemoryPool)
127 };
128 
129 } // namespace QDeclarativeJS
130 
131 QT_QML_END_NAMESPACE
132 
133 #endif
quintptr
QIntegerForSizeof< void * >::Unsigned quintptr
Definition: qglobal.h:986
qFree
Q_CORE_EXPORT void qFree(void *ptr)
Definition: qmalloc.cpp:58
Q_DISABLE_COPY
#define Q_DISABLE_COPY(Class)
Disables the use of copy constructors and assignment operators for the given Class.
Definition: qglobal.h:2523
qMalloc
Q_CORE_EXPORT void * qMalloc(size_t size)
Definition: qmalloc.cpp:53
qRealloc
Q_CORE_EXPORT void * qRealloc(void *ptr, size_t size)
Definition: qmalloc.cpp:63
Q_ASSERT
#define Q_ASSERT(cond)
Definition: qglobal.h:1823
QML_PARSER_EXPORT
#define QML_PARSER_EXPORT
Definition: qdeclarativejsglobal_p.h:61
QT_QML_END_NAMESPACE
#define QT_QML_END_NAMESPACE
Definition: qdeclarativejsglobal_p.h:60
QT_QML_BEGIN_NAMESPACE
#define QT_QML_BEGIN_NAMESPACE
Definition: qdeclarativejsglobal_p.h:59
QSharedData
The QSharedData class is a base class for shared data objects.
Definition: qshareddata.h:56
index
quint16 index
Definition: qfontsubset.cpp:116
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