// 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"

 //

 // Creates a new CReader object.

 //

 CReader::CReader(const TDesC8& aBuffer, TReaderType aType)

  :	iBuffer(aBuffer),

  	iType(aType)

 	{

 	}

 //

 // Returns ETrue is aPattern is in the buffer, EFalse otherwise.

 //

 TBool CReader::Match(const TDesC8& aPattern)

 	{

 	return (iBuffer.Match(aPattern) != KErrNotFound);

 	}

 //

 // Reads aBuf.Length() bytes into a descriptor.

 //

 void CReader::ReadBytesL(TDes8& aBuf)

 	{

 	TInt bufLen = aBuf.Length();

 	if (!CheckEnoughData(bufLen))

 		{

 		User::Leave(KErrEof);

 		}

 	for (TInt i = 0; i < bufLen; i++)

 		{

 		aBuf[i] = iBuffer[iBufPos++];

 		}

 	}

 //

 // Reads a byte from the buffer.

 //

 void CReader::ReadByteL(TUint8& aData)

 	{

 	if (!CheckEnoughData(sizeof(TUint8)))

 		{

 		User::Leave(KErrEof);

 		}

 	aData = iBuffer[iBufPos++];

 	}

 //

 // Reads 16 bits of data at the current reader position.

 // Some formats (mainly those developed by Microsoft) still use little-endian

 // encoding of fields. The file format specifications will specify which

 // byte-ordering scheme is used.

 //

 void CReader::Read16L(TUint16& aData, TBool aLittleEndian)

 	{

 	if (!CheckEnoughData(sizeof(TUint16)))

 		{

 		User::Leave(KErrEof);

 		}

 	TUint8 a = iBuffer[iBufPos++];

 	TUint8 b = iBuffer[iBufPos++];

 	if (aLittleEndian)

 		{

 		aData = (b << 8) | a;

 		}

 	else

 		{

 		aData = (a << 8) | b;

 		}

 	}

 //

 // Reads 32 bits of data at the current reader position.

 // Some formats (mainly those developed by Microsoft) still use little-endian

 // encoding of fields. The file format specifications will specify which

 // byte-ordering scheme is used.

 //

 void CReader::Read32L(TUint32& aData, TBool aLittleEndian)

 	{

 	if (!CheckEnoughData(sizeof(TUint32)))

 		{

 		User::Leave(KErrEof);

 		}

 	TUint8 a = iBuffer[iBufPos++];

 	TUint8 b = iBuffer[iBufPos++];

 	TUint8 c = iBuffer[iBufPos++];

 	TUint8 d = iBuffer[iBufPos++];

 	if (aLittleEndian)

 		{

 		aData = MAKE_INT32(d, c, b, a);

 		}

 	else

 		{

 		aData = MAKE_INT32(a, b, c, d);

 		}

 	}

 //

 // Reads 64 bits of data at the current reader position.

 // Some formats (mainly those developed by Microsoft) still use little-endian

 // encoding of fields. The file format specifications will specify which

 // byte-ordering scheme is used.

 //

 void CReader::Read64L(TInt64& aData, TBool aLittleEndian)

 	{

 	TUint32 high;

 	TUint32 low;

 	Read32L(high, aLittleEndian);

 	Read32L(low, aLittleEndian);

 	if (aLittleEndian)

 		{

 		aData = MAKE_TINT64(low, high);

 		}

 	else

 		{

 		aData = MAKE_TINT64(high, low);

 		}

 	}

 //

 //

 //

 TBool CReader::CheckEnoughData(TInt aNeeded)

 	{

 	return ((iBufPos + aNeeded) <= iBuffer.Length());

 	}

 //

 // Skips forwards or backwards aOffset number of bytes.

 //

 TInt CReader::Seek(TInt aOffset)

 	{

 	TInt newBufPos = iBufPos + aOffset;

 	if ((newBufPos < 0) || (newBufPos >= iBuffer.Length()))

 		{

 		// Trying to seek past the bounds of the buffer.

 		return KErrUnderflow;

 		}

 	iBufPos += aOffset;

 	return KErrNone;

 	}

 //

 // Skips forwards or backwards aOffset number of bytes.

 //

 TInt CReader::Seek(TInt64 aOffset)

     {

     TInt64 newBufPos = iBufPos + aOffset;

     if ((newBufPos < 0) || (newBufPos >= iBuffer.Length()))

         {

         // Trying to seek past the bounds of the buffer.

         return KErrUnderflow;

         }

     iBufPos += aOffset;

     return KErrNone;

     }