CircularBuffer< T > Class Template Reference

Implements a circular buffer. More...

#include <CircularBuffer.h>

List of all members.

Public Member Functions
	CircularBuffer (int nSize)
	Constructor.
	CircularBuffer ()
	Default constructor.
void	Create (int nSize)
	Sets the size for this circular buffer object.
void	Destroy ()
	Deallocates all of the resources taken up by this object.
int	Get (T *pBlock, int n)
	Retrieves the oldest n items in the circular buffer.
bool	Get (T &item)
	Retrieves the oldest item in the circular buffer.
int	GetMaximumSize () const
	Tells the maximum number of items that this circular buffer can store.
int	GetNumItems () const
	Tells the actual number of items stored in this circular buffer.
int	GetRoom () const
	Tells the number of items which can still be stored in this circular buffer.
void	Put (const T *pBlock, int nSize)
	Stores a set of items in the circular buffer.
void	Put (const T &x)
	Stores a single item in the circular buffer.
void	Reset ()
	Empties this circular buffer object.
	~CircularBuffer ()
	Destructor.
Private Attributes
int	m_iReadNext
	Index of next read position.
int	m_iWriteNext
	Index of current feed position.
int	m_nItems
	Number of elements stored in the buffer.
int	m_nSize
	Allocated size (in items).
T *	m_pBuffer
	Pointer to the internal memory buffer.

---

Detailed Description

template<typename T>
class CircularBuffer< T >

Implements a circular buffer.

Parameters:

T

Data type for the contained items.

Definition at line 43 of file CircularBuffer.h.

---

Constructor & Destructor Documentation

template<typename T> CircularBuffer< T >::CircularBuffer (   )  [inline]

Default constructor. Constructs an empty circular buffer object. See also: CircularBuffer(int) Definition at line 88 of file CircularBuffer.h. : m_pBuffer(0) , m_nSize(0) , m_nItems(0) , m_iWriteNext(0) , m_iReadNext(0) {}

template<typename T> CircularBuffer< T >::CircularBuffer (  int  nSize  )  [inline]

Constructor. Constructs a circular buffer object of the specified size. Parameters: nSize  Initial size (in items) of the circular buffer object. See also: CircularBuffer() Definition at line 108 of file CircularBuffer.h. References CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. : m_nSize(nSize) , m_nItems(0) , m_iWriteNext(0) , m_iReadNext(0) { m_pBuffer = (T*)new T[nSize]; memset(m_pBuffer, 0, m_nSize * sizeof(T)); }

template<typename T> CircularBuffer< T >::~CircularBuffer (   )  [inline]

Destructor. Definition at line 122 of file CircularBuffer.h. References CircularBuffer< T >::m_pBuffer. { if(m_pBuffer) delete[] m_pBuffer; }

---

Member Function Documentation

template<typename T> void CircularBuffer< T >::Create (  int  nSize  )  [inline]

Sets the size for this circular buffer object. Parameters: nSize  New size (in mumber of items) for this circular buffer object. Remarks: All of the previous content of the circular buffer is lost. Definition at line 139 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_iWriteNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { if(nSize != m_nSize) { m_nSize = nSize; m_nItems = 0; m_iWriteNext = 0; m_iReadNext = 0; if(m_pBuffer) delete[] m_pBuffer; m_pBuffer = (T*)new T[m_nSize]; memset(m_pBuffer, 0, m_nSize * sizeof(T)); } else { Reset(); } }

template<typename T> void CircularBuffer< T >::Destroy (   )  [inline]

Deallocates all of the resources taken up by this object. Remarks: All of the previous content of the circular buffer is lost. Definition at line 167 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_iWriteNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { m_nSize = 0; m_nItems = 0; m_iWriteNext = 0; m_iReadNext = 0; if(m_pBuffer) { delete[] m_pBuffer; m_pBuffer = 0; } }

template<typename T> int CircularBuffer< T >::Get (  T *  pBlock, int  n )  [inline]

Retrieves the oldest n items in the circular buffer. Parameters: pBlock  Pointer to a buffer which receives the wanted items. n  Number of items to be retrieved. Returns: The number of items which were succesfully retrieved. The returned value is always <= n, 0 if the buffer is empty. See also: Get(T&) Definition at line 361 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { // Cannot give away more than we have! n = (n <= m_nItems) ? n : m_nItems; if((m_iReadNext + n) <= m_nSize) { memcpy(pBlock, m_pBuffer + m_iReadNext, n * sizeof(T)); m_iReadNext = (m_iReadNext + n) % m_nSize; } else { int nPart1 = m_nSize - m_iReadNext; int nPart2 = n - nPart1; memcpy(pBlock, m_pBuffer + m_iReadNext, nPart1 * sizeof(T)); // copy tail memcpy(pBlock + nPart1, m_pBuffer, nPart2 * sizeof(T)); // copy from beginning m_iReadNext = nPart2; } m_nItems -= n; return n; }

template<typename T> bool CircularBuffer< T >::Get (  T &  item  )  [inline]

Retrieves the oldest item in the circular buffer. Parameters: item  [out] Takes the value of the retrieved item. Returns: true if the item was successfully retrieved, false whether the buffer is empty. See also: Get(T*, int) Definition at line 269 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { if(m_nItems) { item = m_pBuffer[m_iReadNext]; m_iReadNext = ++m_iReadNext % m_nSize; --m_nItems; return true; } else { return false; } }

template<typename T> int CircularBuffer< T >::GetMaximumSize (   )  const [inline]

Tells the maximum number of items that this circular buffer can store. Returns: Maximum number of items that this circular buffer can store. Definition at line 201 of file CircularBuffer.h. References CircularBuffer< T >::m_nSize. { return m_nSize; }

template<typename T> int CircularBuffer< T >::GetNumItems (   )  const [inline]

Tells the actual number of items stored in this circular buffer. Returns: The actual number of items stored in this circular buffer. Definition at line 212 of file CircularBuffer.h. References CircularBuffer< T >::m_nItems. { return m_nItems; }

template<typename T> int CircularBuffer< T >::GetRoom (   )  const [inline]

Tells the number of items which can still be stored in this circular buffer. Returns: The number of items which can still be stored in this circular buffer. Definition at line 224 of file CircularBuffer.h. References CircularBuffer< T >::m_nItems, and CircularBuffer< T >::m_nSize. { return m_nSize - m_nItems; }

template<typename T> void CircularBuffer< T >::Put (  const T *  pBlock, int  nSize )  [inline]

Stores a set of items in the circular buffer. Parameters: pBlock  Pointer to a buffer containing the items to be stored. nSize  Number of items to which pBlock points to. See also: Put(const T&) Definition at line 297 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_iWriteNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { // If it doesn't fit, take last m_nSize samples if(nSize > m_nSize) { pBlock = &pBlock[nSize - m_nSize]; // start later, in order to get last m_nSize samples nSize = m_nSize; // limit the length to the buffer's length } // Wrap around buffer end if(m_iWriteNext + nSize > m_nSize) { bool bReadWasBeforeWrite = m_iReadNext < m_iWriteNext; // Fill the end of the buffer memcpy((m_pBuffer + m_iWriteNext), pBlock, (m_nSize - m_iWriteNext) * sizeof(T)); // Restart filling from the beginning of the buffer memcpy(m_pBuffer, (pBlock + m_nSize - m_iWriteNext), (nSize - m_nSize + m_iWriteNext) * sizeof(T)); // Update feed position m_iWriteNext = nSize + m_iWriteNext - m_nSize; // Check if we have written over read position, and move it if(bReadWasBeforeWrite && (m_iReadNext < m_iWriteNext)) m_iReadNext = m_iWriteNext; } else { bool bReadWasAfterWrite = m_iReadNext > m_iWriteNext; // Copy the entire pBlock to the first free location memcpy((m_pBuffer + m_iWriteNext), pBlock, nSize * sizeof(T)); // Update feed position m_iWriteNext = (m_iWriteNext + nSize) % m_nSize; // Check if we have written over read position, and move it if(bReadWasAfterWrite && (m_iReadNext < m_iWriteNext)) m_iReadNext = m_iWriteNext; } // More items in the buffer m_nItems = m_nItems + nSize < m_nSize ? m_nItems + nSize : m_nSize; }

template<typename T> void CircularBuffer< T >::Put (  const T &  x  )  [inline]

Stores a single item in the circular buffer. Parameters: x  Item to be stored. See also: Put(const T*, int) Definition at line 239 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_iWriteNext, CircularBuffer< T >::m_nItems, CircularBuffer< T >::m_nSize, and CircularBuffer< T >::m_pBuffer. { // Copy the sample to the first free location m_pBuffer[m_iWriteNext] = x; ++m_nItems; // Update write index m_iWriteNext = ++m_iWriteNext % m_nSize; // If we have filled the buffer, move to next read position if(m_nItems > m_nSize) { m_nItems = m_nSize; ++m_iReadNext; } }

template<typename T> void CircularBuffer< T >::Reset (   )  [inline]

Empties this circular buffer object. Remarks: The size of this buffer and the allocated memory remain untouched. Definition at line 187 of file CircularBuffer.h. References CircularBuffer< T >::m_iReadNext, CircularBuffer< T >::m_iWriteNext, and CircularBuffer< T >::m_nItems. { m_nItems = 0; m_iWriteNext = 0; m_iReadNext = 0; }

---

Member Data Documentation

template<typename T> int CircularBuffer< T >::m_iReadNext [private]

Index of next read position. Definition at line 74 of file CircularBuffer.h. Referenced by CircularBuffer< T >::Create(), CircularBuffer< T >::Destroy(), CircularBuffer< T >::Get(), CircularBuffer< T >::Put(), and CircularBuffer< T >::Reset().

template<typename T> int CircularBuffer< T >::m_iWriteNext [private]

Index of current feed position. Definition at line 68 of file CircularBuffer.h. Referenced by CircularBuffer< T >::Create(), CircularBuffer< T >::Destroy(), CircularBuffer< T >::Put(), and CircularBuffer< T >::Reset().

template<typename T> int CircularBuffer< T >::m_nItems [private]

Number of elements stored in the buffer. Definition at line 62 of file CircularBuffer.h. Referenced by CircularBuffer< T >::Create(), CircularBuffer< T >::Destroy(), CircularBuffer< T >::Get(), CircularBuffer< T >::GetNumItems(), CircularBuffer< T >::GetRoom(), CircularBuffer< T >::Put(), and CircularBuffer< T >::Reset().

template<typename T> int CircularBuffer< T >::m_nSize [private]

Allocated size (in items). Definition at line 56 of file CircularBuffer.h. Referenced by CircularBuffer< T >::CircularBuffer(), CircularBuffer< T >::Create(), CircularBuffer< T >::Destroy(), CircularBuffer< T >::Get(), CircularBuffer< T >::GetMaximumSize(), CircularBuffer< T >::GetRoom(), and CircularBuffer< T >::Put().

template<typename T> T* CircularBuffer< T >::m_pBuffer [private]

Pointer to the internal memory buffer. Definition at line 50 of file CircularBuffer.h. Referenced by CircularBuffer< T >::CircularBuffer(), CircularBuffer< T >::Create(), CircularBuffer< T >::Destroy(), CircularBuffer< T >::Get(), CircularBuffer< T >::Put(), and CircularBuffer< T >::~CircularBuffer().

---