// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

//

#include "readers.h"

//

//

//

CFileReader::CFileReader(RFile* aFile)

 :	CBufferReader(iFileBuffer, CReader::EFile),

 	iFile(aFile)

	{

	}

//

//

//

CFileReader::~CFileReader()

	{

	}

//

//

//

CFileReader* CFileReader::NewLC(RFile* aFile)

	{

	CFileReader* self = new(ELeave) CFileReader(aFile);

	CleanupStack::PushL(self);

	self->ConstructL();

	return self;

	}

//

//

//

void CFileReader::ConstructL()

	{

	TInt pos = 0;

	User::LeaveIfError(iFile->Seek(ESeekStart, pos));

	User::LeaveIfError(iFile->Read(iFileBuffer));

	}

//

// Checks if there is aAmount of data left in the buffer.

// It is important to call the base-class implementation first

// to ensure correct operation.

//

TBool CFileReader::CheckEnoughData(TInt aAmount)

	{

	if (CBufferReader::CheckEnoughData(aAmount))

		{

		return ETrue;

		}

	// Try to read more data.

	TInt bufPos = CBufferReader::Position();

	TInt err = PhysicallySeekAndRead(bufPos - iFileBuffer.Length());

	if (err == KErrNone)

		{

		// The read may have succeeded but that 

		// still doesn't mean we have enough data.

		return (aAmount <= iFileBuffer.Length());

		}

	return EFalse;

	}

//

//

//

void CFileReader::Reset()

	{

	CBufferReader::Reset(); // This will reset iBufPos.

	if (iFilePos != 0)

		{

		// We need to seek to the start and fill the buffer.

		iFilePos = 0;

		TInt err = iFile->Seek(ESeekStart, iFilePos);

		if (err == KErrNone)

			{

			err = iFile->Read(iFileBuffer);

			}

		if (err != KErrNone)

			{

			iFileBuffer.Zero();

			}

		}

	else

		{

		// There's no need to seek and read.

		iFilePos = 0;

		}

	}

//

//

//

void CFileReader::SeekL(TInt aOffset)

	{

	TInt err = CReader::Seek(aOffset);

	if (err == KErrUnderflow)

		{

		TInt bufPos = CBufferReader::Position();

		aOffset += bufPos - iFileBuffer.Length();

		User::LeaveIfError(PhysicallySeekAndRead(aOffset));

		}

	}

//

// It could be possible for a 64-bit field in formats such as MPEG4

// to have values that would fit in a 32-bit variable. In this case

// we can use it for seeking. This function checks if a 64-bit value

// is compatible with RFile's 32-bit operations.

//

void CFileReader::SeekL(TInt64 aOffset)

	{

	if (aOffset < (TInt64)KMinTInt)

		{

		User::Leave(KErrNotSupported);

		}

	if (aOffset > (TInt64)KMaxTInt)

		{

		User::Leave(KErrNotSupported);

		}

	TInt low = (TInt)I64LOW(aOffset);

	SeekL(low);

	}

//

// This function seeks forward/backward aOffset bytes

// and fills the buffer from that point.

//

TInt CFileReader::PhysicallySeekAndRead(TInt aOffset)

	{

	TInt err;

	// New buffer contents so read from the start of it.

	CBufferReader::Reset();

	iFilePos = aOffset;

	err = iFile->Seek(ESeekCurrent, iFilePos);

	if (err != KErrNone)

		{

		return err;

		}

	err = iFile->Read(iFileBuffer);

	if (err != KErrNone)

		{

		return err;

		}

	return (iFileBuffer.Length() == 0 ? KErrEof : KErrNone);

	}