/*

* Copyright (c) 2000-2009 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 <e32std.h>

#include <convgeneratedcpp.h>

#include "gb2312.h"

struct SCnvConversionData;

EXPORT_C const TDesC8& CnvGb2312::ReplacementForUnconvertibleUnicodeCharacters()

	{

	return ReplacementForUnconvertibleUnicodeCharacters_internal();

	}

EXPORT_C const SCnvConversionData& CnvGb2312::ConversionData()

	{

	return conversionData;

	}

EXPORT_C TBool CnvGb2312::IsCharGBBased(TInt& aConfidenceLevel, const TDesC8& aSample)

	{

	TInt sampleLength = aSample.Length();

	aConfidenceLevel = 0;

	//WBB the following is for distiguish between big5 and GBK

	TInt totalWeight=0;		//sum of the weights of 20 most frequent chars

	TInt sumOfGoodChar=0;		//the number of chars whose first byte and second are both in the range

	TInt sumOfWeight=0;		//sum of the weights of the chars which are included in the sample

	TInt sumOutChar=0;		//the number of chars which are not common

	TInt sumOfBadSecondByte=0;//the number of chars whose first byte is in the range but not the second

	struct referenceChar

		{

		TUint charGBK;

		TInt weight;

		};

	referenceChar refGbk[20];

	static const TInt iniWeight[20]=

		{

		//occurence per 1000 chars

		30,20,20,10,10,10,10,10,5,5,

		5,5,5,5,5,5,5,5,5,5

		};

	static const TUint iniChar[20]=

		{

		0xa3ac,0xb5c4,0xc1cb,0xb8f6,0xb2bb,0xb0d1,0xd2bb,0xcac7,0xd2aa,0xbecd,

		0xd2b2,0xccec,0xc9cf,0xbacd,0xd6d0,0xd4da,0xd0a1,0xc8cb,0xcfc2,0xd6d0,

		};

	for (TInt k=0; k<20; k++)

		{

		refGbk[k].charGBK=iniChar[k];

		refGbk[k].weight=iniWeight[k];

		totalWeight=totalWeight+iniWeight[k];

		}

	//WBB

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

		{

		//GBK encoding first byte range 0x81-0xfe

		//              second byte range 0x40-0x7e, 0x80-0xfe

		if((aSample[i] >= 0x81) && (aSample[i] <= 0xfe))

			{

			TInt increment1 = i+1;

			if (increment1 >= sampleLength)

				break;

			if (((aSample[increment1] >=0x40) && (aSample[increment1] <= 0x7e)) ||

				((aSample[increment1] >=0x80) && (aSample[increment1] <= 0xfe)))

				{

				//WBB

				TUint charGbk=(aSample[i]<<8)|(aSample[increment1]);

				TInt j;

				for (j=0; j<20; j++)

					{

					if (charGbk==refGbk[j].charGBK)

						{

						sumOfWeight=sumOfWeight+refGbk[j].weight;

						break;

						}

					}

				if ((aSample[i]>=0xa4)&&(aSample[i]<=0xaf))

					sumOutChar++;

				sumOfGoodChar++;

				i++;

				//WBB

				}

			else

				{

				sumOfBadSecondByte++;				

				}

			}

		} // for 

	TInt limit;

	limit = (10*sampleLength)/100;

	if (sumOfGoodChar > limit)

		{

		aConfidenceLevel=sumOfGoodChar*100/(sumOfBadSecondByte+sumOfGoodChar);

		aConfidenceLevel=aConfidenceLevel-Max(0,((totalWeight-sumOfWeight)*sumOfGoodChar/1000));//against frequent chars 

		aConfidenceLevel=aConfidenceLevel-(sumOutChar*100/sumOfGoodChar);//against gap

		aConfidenceLevel=(aConfidenceLevel < 0)?0:aConfidenceLevel;

		}

	else

		aConfidenceLevel=0;

	return ETrue;

	}