/*

* Copyright (c) 1997-2009 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: 

* Big-Endian converter

*

*/

#include <e32std.h>

#include <convdata.h>

#include "unicode.h"

#define ARRAY_LENGTH(aArray) (sizeof(aArray)/sizeof((aArray)[0]))

GLREF_D const SCnvConversionData unicodeConversionDataBig=

	{

	SCnvConversionData::EFixedBigEndian,

		{

		ARRAY_LENGTH(unicodeVariableByteDataRanges),

		unicodeVariableByteDataRanges

		},

		{

		ARRAY_LENGTH(unicodeTounicodeDataRanges),

		unicodeTounicodeDataRanges

		},

		{

		ARRAY_LENGTH(unicodeTounicodeDataRanges),

		unicodeTounicodeDataRanges

		},

	NULL,

	NULL

	};

GLREF_C void IsCharacterSetUnicodeBig(TInt& aConfidenceLevel, const TDesC8& aSample)

	{

	TInt sampleLength = aSample.Length();

	aConfidenceLevel =70;

	if (sampleLength < 2)

		return;

	if (aSample[0]==0xfe)

		{

		// The first byte is a possible ByteOrderMark

		// Try matching the next character 

		if(aSample[1]==0xff)

			{

			// the byte order mark could be 0xFEFF or 0xFFFE depending on 

			// endianness of the sample text.

			aConfidenceLevel=100;

			}

		}

	for (TInt i = 0; i < sampleLength-1; ++i)

		{

		if (aSample[i] == 0x0d)

 			{

 			if (aSample[i+1] == 0x0a)

 				{

 				// Reduce the confidence level

 				aConfidenceLevel-= 25;

 				}

 			}

		}

	// if not 100% confident already, check if most even bytes are 0

	#define MAX_SAMPLE_LENGTH 2048

	if ( aConfidenceLevel < 100 )

		{	

		TInt repeat=0;

		// only check the first 2k if big sample

		TInt length =( sampleLength > MAX_SAMPLE_LENGTH ? MAX_SAMPLE_LENGTH : sampleLength);

		// start from 0 and check the even bytes

		for (TInt i = 0; i < length-1; i+=2)

			{

			if (aSample[i] == 0x0) 

				repeat ++;

			}

		// if more than 80% even bytes zero then this IS big Endian

		if ( (repeat * 100) /  (length * 5) >= 8)

			aConfidenceLevel  = 100;

		}

	aConfidenceLevel =(aConfidenceLevel >0)? ((aConfidenceLevel > 100)? 100: aConfidenceLevel): 0;

	}