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/*******************************************************************************
* Copyright (C) ST-Ericsson SA 2011
* License terms: 3-clause BSD license
******************************************************************************/
#ifndef _LOCKLESSQUEUE_H_
#define _LOCKLESSQUEUE_H_
/// <summary>
/// Class for store received data in Z-protocol in a lockless queue.
/// </summary>
class LockLessQueue
{
unsigned char *m_puchQueue;
unsigned int m_uiHead;
unsigned int m_uiTail;
unsigned int m_uiSize;
unsigned int m_uiMask;
public:
/// <summary>
/// Constructor.
/// </summary>
/// <param name="uiSize">Size of buffer = 2^uiSize.</param>
LockLessQueue(unsigned int uiSize): m_uiHead(0), m_uiTail(0) {
m_uiSize = 1 << uiSize;
m_uiMask = m_uiSize - 1;
m_puchQueue = new unsigned char[m_uiSize];
}
/// <summary>
/// Constructor. Default buffer size to 2^20.
/// </summary>
LockLessQueue(): m_uiHead(0), m_uiTail(0) {
m_uiSize = 1 << 20;
m_uiMask = m_uiSize - 1;
m_puchQueue = new unsigned char[m_uiSize];
}
/// <summary>
/// Destructor.
/// </summary>
~LockLessQueue() {
if (m_puchQueue != 0) {
delete [] m_puchQueue;
}
}
/// <summary>
/// Store one byte in buffer queue.
/// </summary>
/// <param name="uchData">Data to store in buffer.</param>
/// <param name="pbFull">Status of buffer, true = full buffer.</param>
void Push(unsigned char uchData, bool *pbFull) {
unsigned int uiHead = m_uiHead;
uiHead = uiHead & m_uiMask; //(Head++) & m_uiMask -> This does the required roll over to zero at the end of the array.
uiHead++;
if (uiHead == m_uiTail) {
*pbFull = true;
} else {
m_puchQueue[uiHead] = uchData;
m_uiHead = uiHead;
*pbFull = false;
}
}
/// <summary>
/// Take out one byte from buffer queue.
/// </summary>
/// <param name="pbEmpty">Status of buffer. pbEmpty = true -> buffer is empty.</param>
/// <returns> One byte data from buffer queue.</returns>
unsigned char Pop(bool *pbEmpty) {
unsigned char uchPopData = 0;
unsigned int uiTail = m_uiTail;
if (m_uiHead != uiTail) {
uiTail = (uiTail + 1) & m_uiMask; //This does the required roll over to zero at the end of the array.
m_uiTail = uiTail;
uchPopData = m_puchQueue[uiTail];
*pbEmpty = false;
} else {
*pbEmpty = true;
}
return uchPopData;
}
/// <summary>
/// Reset buffer queue.
/// </summary>
void Clear() {
m_uiTail = m_uiHead;
}
};
#endif // _LOCKLESSQUEUE_H_
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