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Amiga Plus 2004 #11
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Amiga Plus CD - 2004 - No. 11.iso
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AmiSoft
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Util
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Acvt.lha
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Acvt 1.07
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cprefile.cpp
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2001-03-08
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// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
#include "cprefile.h"
CPreFile::CPreFile()
{
m_lCacheStartOffset = -1;
m_lCacheEndOffset = -1;
m_bOpened = FALSE;
m_pbtCache = NULL;
}
CPreFile::~CPreFile()
{
Close();
}
BOOL CPreFile::Open( CGenFile* pcf, int iCacheSizeKB )
{
m_lCacheLen = 1024 * iCacheSizeKB;
if ( m_bOpened )
return FALSE;
m_pcf = pcf;
m_pcf->Seek( 0, SEEK_END );
m_lLength = m_pcf->Tell();
if ( m_lLength < m_lCacheLen )
{
m_lCacheLen = m_lLength;
}
if ( ! ( m_pbtCache = new BYTE [ m_lCacheLen ] ) )
return FALSE;
m_pcf->Seek( 0, SEEK_SET );
m_lCurrPtr = 0;
m_bOpened = TRUE;
PreRead();
return TRUE;
}
BOOL CPreFile::PreRead()
{
m_pcf->Seek( m_lCurrPtr, SEEK_SET );
m_lCacheStartOffset = m_lCurrPtr;
m_lCacheEndOffset = m_lCacheStartOffset + m_lCacheLen - 1;
m_pcf->Read( m_pbtCache, m_lCacheLen );
return TRUE;
}
BOOL CPreFile::Read( void* pBuff, int iLen, int* piLen )
{
if ( !m_bOpened )
return FALSE;
if ( m_lCurrPtr > m_lLength )
return FALSE;
if ( iLen >= m_lCacheLen )
{
m_pcf->Seek( m_lCurrPtr, SEEK_SET );
if ( !m_pcf->Read( pBuff, iLen, piLen ) )
return FALSE;
m_lCurrPtr = m_pcf->Tell();
m_lCacheEndOffset = -1;
return TRUE;
}
if ( ( m_lCurrPtr < m_lCacheStartOffset ) || ( m_lCurrPtr > m_lCacheEndOffset ) )
PreRead();
long lReadEnd = m_lCurrPtr + iLen - 1;
if ( lReadEnd >= m_lCacheEndOffset )
{
m_pcf->Seek( m_lCurrPtr, SEEK_SET );
if ( !m_pcf->Read( pBuff, iLen, piLen ) )
return FALSE;
m_lCurrPtr = m_pcf->Tell();
m_lCacheEndOffset = -1;
return TRUE;
}
memcpy( pBuff, m_pbtCache + m_lCurrPtr - m_lCacheStartOffset, iLen );
m_lCurrPtr += iLen;
return TRUE;
}
BOOL CPreFile::Write( void* pBuff, int iLen, int* piLen )
{
return FALSE;
}
BOOL CPreFile::Seek( long lPos, int iType )
{
switch( iType )
{
case SEEK_SET:
m_lCurrPtr = lPos;
break;
case SEEK_CUR:
m_lCurrPtr += lPos;
break;
case SEEK_END:
m_lCurrPtr = m_lLength - lPos;
break;
}
return TRUE;
}
void CPreFile::Close()
{
m_bOpened = FALSE;
if ( m_pbtCache )
delete [] m_pbtCache;
m_pbtCache = NULL;
m_lCurrPtr = 0;
}