xmemfile.cpp from aMSN at Krugle
Show xmemfile.cpp syntax highlighted
#include "xmemfile.h"
//////////////////////////////////////////////////////////
CxMemFile::CxMemFile(BYTE* pBuffer, DWORD size)
{
m_pBuffer = pBuffer;
m_Position = 0;
m_Size = m_Edge = size;
m_bFreeOnClose = (bool)(pBuffer==0);
}
//////////////////////////////////////////////////////////
CxMemFile::~CxMemFile()
{
Close();
}
//////////////////////////////////////////////////////////
bool CxMemFile::Close()
{
if ( (m_pBuffer) && (m_bFreeOnClose) ){
free(m_pBuffer);
m_pBuffer = NULL;
m_Size = 0;
}
return true;
}
//////////////////////////////////////////////////////////
bool CxMemFile::Open()
{
if (m_pBuffer) return false; // Can't re-open without closing first
m_Position = m_Size = m_Edge = 0;
m_pBuffer=(BYTE*)malloc(1);
m_bFreeOnClose = true;
return (m_pBuffer!=0);
}
//////////////////////////////////////////////////////////
BYTE* CxMemFile::GetBuffer(bool bDetachBuffer)
{
m_bFreeOnClose = !bDetachBuffer;
return m_pBuffer;
}
//////////////////////////////////////////////////////////
size_t CxMemFile::Read(void *buffer, size_t size, size_t count)
{
if (buffer==NULL) return 0;
if (m_pBuffer==NULL) return 0;
if (m_Position >= (long)m_Size) return 0;
long nCount = (long)(count*size);
if (nCount == 0) return 0;
long nRead;
if (m_Position + nCount > (long)m_Size)
nRead = (m_Size - m_Position);
else
nRead = nCount;
memcpy(buffer, m_pBuffer + m_Position, nRead);
m_Position += nRead;
return (size_t)(nRead/size);
}
//////////////////////////////////////////////////////////
size_t CxMemFile::Write(const void *buffer, size_t size, size_t count)
{
if (m_pBuffer==NULL) return 0;
if (buffer==NULL) return 0;
long nCount = (long)(count*size);
if (nCount == 0) return 0;
if (m_Position + nCount > m_Edge) Alloc(m_Position + nCount);
memcpy(m_pBuffer + m_Position, buffer, nCount);
m_Position += nCount;
if (m_Position > (long)m_Size) m_Size = m_Position;
return count;
}
//////////////////////////////////////////////////////////
bool CxMemFile::Seek(long offset, int origin)
{
if (m_pBuffer==NULL) return false;
long lNewPos = m_Position;
if (origin == SEEK_SET) lNewPos = offset;
else if (origin == SEEK_CUR) lNewPos += offset;
else if (origin == SEEK_END) lNewPos = m_Size + offset;
else return false;
if (lNewPos < 0) lNewPos = 0;
m_Position = lNewPos;
return true;
}
//////////////////////////////////////////////////////////
long CxMemFile::Tell()
{
if (m_pBuffer==NULL) return -1;
return m_Position;
}
//////////////////////////////////////////////////////////
long CxMemFile::Size()
{
if (m_pBuffer==NULL) return -1;
return m_Size;
}
//////////////////////////////////////////////////////////
bool CxMemFile::Flush()
{
if (m_pBuffer==NULL) return false;
return true;
}
//////////////////////////////////////////////////////////
bool CxMemFile::Eof()
{
if (m_pBuffer==NULL) return true;
return (m_Position >= (long)m_Size);
}
//////////////////////////////////////////////////////////
long CxMemFile::Error()
{
if (m_pBuffer==NULL) return -1;
return (m_Position > (long)m_Size);
}
//////////////////////////////////////////////////////////
bool CxMemFile::PutC(unsigned char c)
{
if (m_pBuffer==NULL) return false;
if (m_Position + 1 > m_Edge) Alloc(m_Position + 1);
memcpy(m_pBuffer + m_Position, &c, 1);
m_Position += 1;
if (m_Position > (long)m_Size) m_Size = m_Position;
return true;
}
//////////////////////////////////////////////////////////
long CxMemFile::GetC()
{
if (Eof()) return EOF;
return *(BYTE*)((BYTE*)m_pBuffer + m_Position++);
}
//////////////////////////////////////////////////////////
void CxMemFile::Alloc(DWORD dwNewLen)
{
if (dwNewLen > (DWORD)m_Edge)
{
// find new buffer size
DWORD dwNewBufferSize = (DWORD)(((dwNewLen>>12)+1)<<12);
// allocate new buffer
if (m_pBuffer == NULL) m_pBuffer = (BYTE*)malloc(dwNewBufferSize);
else m_pBuffer = (BYTE*)realloc(m_pBuffer, dwNewBufferSize);
// I own this buffer now (caller knows nothing about it)
m_bFreeOnClose = true;
m_Edge = dwNewBufferSize;
}
return;
}
//////////////////////////////////////////////////////////
void CxMemFile::Free()
{
Close();
}
//////////////////////////////////////////////////////////
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