151 lines
2.3 KiB
C++
151 lines
2.3 KiB
C++
#include "StdAfx.h"
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#include "Buffer.h"
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#include <math.h>
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#define U_PAGE_ALIGNMENT 3
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#define F_PAGE_ALIGNMENT 3.0
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CBuffer::CBuffer()
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{
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m_ulMaxLength = 0;
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m_Ptr = m_Base = NULL;
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}
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CBuffer::~CBuffer(void)
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{
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if (m_Base)
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{
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VirtualFree(m_Base, 0, MEM_RELEASE);
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m_Base = NULL;
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}
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m_Base = m_Ptr = NULL;
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m_ulMaxLength = 0;
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}
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ULONG CBuffer::ReadBuffer(PBYTE Buffer, ULONG ulLength)
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{
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if (ulLength > m_ulMaxLength)
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{
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return 0;
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}
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ULONG len = m_Ptr - m_Base;
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if (ulLength > len)
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{
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ulLength = len;
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}
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if (ulLength)
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{
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CopyMemory(Buffer,m_Base,ulLength);
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MoveMemory(m_Base,m_Base+ulLength, m_ulMaxLength - ulLength);
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m_Ptr -= ulLength;
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}
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DeAllocateBuffer(m_Ptr - m_Base);
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return ulLength;
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}
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// 重新分配内存大小
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VOID CBuffer::DeAllocateBuffer(ULONG ulLength)
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{
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int len = m_Ptr - m_Base;
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if (ulLength < len)
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return;
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ULONG ulNewMaxLength = ceil(ulLength / F_PAGE_ALIGNMENT) * U_PAGE_ALIGNMENT;
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if (m_ulMaxLength <= ulNewMaxLength)
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{
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return;
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}
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PBYTE NewBase = (PBYTE) VirtualAlloc(NULL,ulNewMaxLength,MEM_COMMIT,PAGE_READWRITE);
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if (NewBase == NULL)
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return;
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CopyMemory(NewBase,m_Base,len);
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VirtualFree(m_Base,0,MEM_RELEASE);
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m_Base = NewBase;
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m_Ptr = m_Base + len;
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m_ulMaxLength = ulNewMaxLength;
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}
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BOOL CBuffer::WriteBuffer(PBYTE Buffer, ULONG ulLength)
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{
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if (ReAllocateBuffer(ulLength + (m_Ptr - m_Base)) == FALSE)
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{
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return FALSE;
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}
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CopyMemory(m_Ptr, Buffer, ulLength);
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m_Ptr+=ulLength;
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return TRUE;
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}
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// 当缓存长度不足时重新分配
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BOOL CBuffer::ReAllocateBuffer(ULONG ulLength)
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{
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if (ulLength < m_ulMaxLength)
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return TRUE;
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ULONG ulNewMaxLength = ceil(ulLength / F_PAGE_ALIGNMENT) * U_PAGE_ALIGNMENT;
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PBYTE NewBase = (PBYTE) VirtualAlloc(NULL,ulNewMaxLength,MEM_COMMIT,PAGE_READWRITE);
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if (NewBase == NULL)
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{
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return FALSE;
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}
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ULONG len = m_Ptr - m_Base;
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CopyMemory(NewBase, m_Base, len);
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if (m_Base)
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{
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VirtualFree(m_Base,0,MEM_RELEASE);
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}
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m_Base = NewBase;
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m_Ptr = m_Base + len;
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m_ulMaxLength = ulNewMaxLength;
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return TRUE;
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}
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VOID CBuffer::ClearBuffer()
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{
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m_Ptr = m_Base;
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DeAllocateBuffer(1024);
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}
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ULONG CBuffer::GetBufferLength() const
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{
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return m_Ptr - m_Base;
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}
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PBYTE CBuffer::GetBuffer(ULONG ulPos) const
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{
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if (m_Base==NULL || ulPos>=(m_Ptr - m_Base))
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{
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return NULL;
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}
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return m_Base+ulPos;
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}
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