111 lines
2 KiB
C++
111 lines
2 KiB
C++
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/*++
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Copyright (C) 1996-2001 Microsoft Corporation
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Module Name:
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FLEXQ.CPP
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Abstract:
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CFlexQueue.
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History:
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--*/
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#include "precomp.h"
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//#include <dbgalloc.h>
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#include <flexq.h>
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CFlexQueue::CFlexQueue(int nInitialSize) :
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m_nSize(nInitialSize), m_nHeadIndex(0), m_nTailIndex(0)
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{
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if(m_nSize)
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m_ppData = new void*[m_nSize];
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else
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m_ppData = NULL;
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}
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CFlexQueue::~CFlexQueue()
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{
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delete [] m_ppData;
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}
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bool CFlexQueue::Grow()
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{
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int nNewSize = (m_nSize + 1) * 2;
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// Allocate new memory block
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// =========================
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void** ppNewData = new void*[nNewSize];
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if(ppNewData == NULL)
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return false;
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// Copy the queue data to the beginning of the array
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// =================================================
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if(m_nHeadIndex <= m_nTailIndex)
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{
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memcpy(ppNewData, m_ppData + m_nHeadIndex,
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(m_nTailIndex - m_nHeadIndex) * sizeof(void*));
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}
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else
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{
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memcpy(ppNewData, m_ppData + m_nHeadIndex,
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(m_nSize - m_nHeadIndex) * sizeof(void*));
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memcpy(ppNewData + (m_nSize - m_nHeadIndex), m_ppData,
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m_nTailIndex * sizeof(void*));
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}
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m_nTailIndex = GetQueueSize();
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m_nHeadIndex = 0;
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m_nSize = nNewSize;
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delete [] m_ppData;
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m_ppData = ppNewData;
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return true;
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}
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bool CFlexQueue::Enqueue(void* pNew)
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{
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if(GetQueueSize() >= m_nSize - 1)
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{
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if(!Grow()) return false;
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}
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m_ppData[m_nTailIndex] = pNew;
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IncrementIndex(m_nTailIndex);
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return true;
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}
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void* CFlexQueue::Dequeue()
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{
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if(GetQueueSize() == 0)
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return NULL;
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void* pRet = m_ppData[m_nHeadIndex];
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IncrementIndex(m_nHeadIndex);
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return pRet;
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}
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void* CFlexQueue::Peek()
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{
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if(GetQueueSize() == 0)
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return NULL;
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return m_ppData[m_nHeadIndex];
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}
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bool CFlexQueue::Requeue(void* pNew)
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{
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if(GetQueueSize() >= m_nSize - 1)
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{
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if(!Grow()) return false;
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}
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DecrementIndex(m_nHeadIndex);
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m_ppData[m_nHeadIndex] = pNew;
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return true;
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}
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