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// --------------------------------------------------------------------------
//
// File
// Name: ZeroStream.cpp
// Purpose: An IOStream which returns all zeroes up to a certain size
// Created: 2007/04/28
//
// --------------------------------------------------------------------------
#include "Box.h"
#include "ZeroStream.h"
#include "CommonException.h"
#include <string.h>
#include "MemLeakFindOn.h"
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::ZeroStream(IOStream::pos_type)
// Purpose: Constructor
// Created: 2007/04/28
//
// --------------------------------------------------------------------------
ZeroStream::ZeroStream(IOStream::pos_type size)
: mSize(size), mPosition(0)
{ }
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::Read(void *, int)
// Purpose: Reads bytes from the file
// Created: 2007/01/16
//
// --------------------------------------------------------------------------
int ZeroStream::Read(void *pBuffer, int NBytes, int Timeout)
{
ASSERT(NBytes > 0);
int bytesToRead = NBytes;
if (bytesToRead > mSize - mPosition)
{
bytesToRead = mSize - mPosition;
}
memset(pBuffer, 0, bytesToRead);
mPosition += bytesToRead;
return bytesToRead;
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::BytesLeftToRead()
// Purpose: Returns number of bytes to read (may not be most efficient function ever)
// Created: 2007/01/16
//
// --------------------------------------------------------------------------
IOStream::pos_type ZeroStream::BytesLeftToRead()
{
return mSize - mPosition;
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::Write(void *, int)
// Purpose: Writes bytes to the underlying stream (not supported)
// Created: 2003/07/31
//
// --------------------------------------------------------------------------
void ZeroStream::Write(const void *pBuffer, int NBytes)
{
THROW_EXCEPTION(CommonException, NotSupported);
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::GetPosition()
// Purpose: Get position in stream
// Created: 2003/08/21
//
// --------------------------------------------------------------------------
IOStream::pos_type ZeroStream::GetPosition() const
{
return mPosition;
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::Seek(pos_type, int)
// Purpose: Seeks within file, as lseek, invalidate buffer
// Created: 2003/07/31
//
// --------------------------------------------------------------------------
void ZeroStream::Seek(IOStream::pos_type Offset, int SeekType)
{
switch (SeekType)
{
case SeekType_Absolute:
{
mPosition = Offset;
}
break;
case SeekType_Relative:
{
mPosition += Offset;
}
break;
case SeekType_End:
{
mPosition = mSize - Offset;
}
}
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::Close()
// Purpose: Closes the underlying stream (not needed)
// Created: 2003/07/31
//
// --------------------------------------------------------------------------
void ZeroStream::Close()
{
THROW_EXCEPTION(CommonException, NotSupported);
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::StreamDataLeft()
// Purpose: Any data left to write?
// Created: 2003/08/02
//
// --------------------------------------------------------------------------
bool ZeroStream::StreamDataLeft()
{
return (BytesLeftToRead() > 0);
}
// --------------------------------------------------------------------------
//
// Function
// Name: ZeroStream::StreamClosed()
// Purpose: Is the stream closed?
// Created: 2003/08/02
//
// --------------------------------------------------------------------------
bool ZeroStream::StreamClosed()
{
return false;
}
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