// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of the License "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:
// f32\sfat\sl_check.cpp
// 
//

//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
//!!
//!! WARNING!! DO NOT edit this file !! '\sfat' component is obsolete and is not being used. '\sfat32'replaces it
//!!
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

#include "sl_std.h"
#include "sl_scandrv.h"

const TInt KMaxBufferSize=8192;


TBool CCheckFatTable::IsEof16Bit(TInt aCluster) const
{
    return(aCluster>=0xFFF8 && aCluster<=0xFFFF);
}

TBool CCheckFatTable::IsEof12Bit(TInt aCluster) const
{
    return(aCluster>=0xFF8 && aCluster<=0xFFF);
}

TInt CCheckFatTable::MaxFatIndex() const
    {   
    __ASSERT_DEBUG((TUint)iMaxFatIndex>=KFatFirstSearchCluster, Fault(ECheckFatIndexZero));
    return(iMaxFatIndex);
    }


CCheckFatTable* CCheckFatTable::NewL(CFatMountCB* aOwner)
//
// Create a CCheckFatTable
//
    {
    CCheckFatTable* fatTable;
    fatTable=new(ELeave) CCheckFatTable(aOwner);
    return(fatTable);
    }


CCheckFatTable::CCheckFatTable(CFatMountCB* aOwner)
//
// Constructor
//
    {
    iOwner=aOwner;
    }

CCheckFatTable::~CCheckFatTable()
//
// Destructor
//
    {
    User::Free(iCheckFat);
    }


void CCheckFatTable::InitializeL()
//
// Initialize the check fat table
//
    {
    __PRINT(_L("CCheckFatTable::InitializeL"));

    TInt fatSize=iOwner->FatSizeInBytes();

    if(iCheckFat==NULL)
        iCheckFat=(TUint8*)User::AllocL(fatSize);
    else
        iCheckFat=(TUint8*)User::ReAllocL(iCheckFat,fatSize);
    Mem::FillZ(iCheckFat,fatSize);
    iMaxFatIndex=iOwner->UsableClusters()+1;
    if(iOwner->Is16BitFat())
        {
        __ASSERT_ALWAYS(iMaxFatIndex>0 && iMaxFatIndex<EOF_16Bit && !IsEof16Bit(iMaxFatIndex),User::Leave(KErrCorrupt));
        }
    else
        {
        __ASSERT_ALWAYS(iMaxFatIndex>0 && iMaxFatIndex<EOF_12Bit && !IsEof12Bit(iMaxFatIndex),User::Leave(KErrCorrupt));
        }
    WriteMediaDescriptor();
    
    __PRINT2(_L("fatSize=%d,iCheckFat=0x%x"),fatSize,iCheckFat);
    }


/**
@return ETrue if found errors in FAT 
*/
TBool CCheckFatTable::FlushL()
//
// Flush iCheckFat to the media, comparing each sector to corresponding 
// sector in all fats (cf.CFixedCache::FlushL)
//  
    {
    TBool bErrFound = EFalse;
    
    __PRINT(_L("CCheckFatTable::FlushL()"));
    HBufC8* hBuf=HBufC8::New(KMaxBufferSize);
    if (hBuf==NULL)
        hBuf=HBufC8::NewL(KMaxBufferSize/4);
    CleanupStack::PushL(hBuf);

    TUint8* ptr=(TUint8*)hBuf->Ptr();
    TInt maxSize=hBuf->Des().MaxSize();

    TPtr8 fatBuffer(ptr,maxSize);
    TInt fatSize=iOwner->FatSizeInBytes();
    TInt remainder=fatSize;
    TInt offset=iOwner->StartOfFatInBytes();
    TUint8* dataPtr=iCheckFat;
    TFatDriveInterface& drive = iOwner->DriveInterface();
    TInt fatNumber=iOwner->NumberOfFats();
    
    while(remainder)
        {
        TInt s=Min(fatBuffer.MaxSize(),remainder);
        TInt fatCount=fatNumber;
        TInt fatPos=0;
        while(fatCount)
            {
            TInt fatOffset=offset+fatPos;
            User::LeaveIfError(drive.ReadCritical(fatOffset,s,fatBuffer));
            TInt rem2=s;
            TInt offset2=fatOffset;
            TUint8* dataPtr2=dataPtr;
            TInt bufOffset=0;
            while(rem2)
                {
                TInt s2=Min(rem2,512);
                TInt r=Mem::Compare(dataPtr2,s2,fatBuffer.Ptr()+bufOffset,s2);
                if (r!=0)
                    {
                    bErrFound = ETrue;
                    TPtrC8 dataBuf(dataPtr2,s2);
                    User::LeaveIfError(drive.WriteCritical(offset2,dataBuf));
                    }
                rem2-=s2;
                offset2+=s2;
                dataPtr2+=s2;
                bufOffset+=s2;
                }
            --fatCount;
            fatPos+=fatSize;
            }
        offset+=s;
        dataPtr+=s;
        remainder-=s;
        }

    CleanupStack::PopAndDestroy();

    return bErrFound;
    }

void CCheckFatTable::WriteMediaDescriptor()
//
// Write media descriptor to first byte and 0xFF to
// remaining bytes of first two entries
//
    {
    __PRINT(_L("CCheckFatTable::WriteMediaDescriptor"));
    iCheckFat[0]=KBootSectorMediaDescriptor;
    iCheckFat[1]=0xFF;
    iCheckFat[2]=0xFF;
    if (iOwner->Is16BitFat())
        iCheckFat[3]=0xFF;
    }

TInt CCheckFatTable::PosInBytes(TInt aFatIndex) const
//
// Return number of bytes into the fat
//
    {
    TInt fatPosInBytes;
    if (iOwner->Is16BitFat())
        fatPosInBytes=aFatIndex<<1;
    else
        // this is used since 8-bit access will be used for reading/writing
        fatPosInBytes=(aFatIndex*3>>1);
    return(fatPosInBytes);
    }


TInt CCheckFatTable::PosInIndex(TInt aBytePos) const
//
// Return index given byte position in fat
//
    {
    if(iOwner->Is16BitFat())
        return(aBytePos>>1);
    else
        return((aBytePos<<1)/3);
    }


TInt CCheckFatTable::ReadL(TInt aFatIndex) const
//
// Read a value from the check fat
//
    {
    __ASSERT_ALWAYS((TUint32)aFatIndex >=KFatFirstSearchCluster && aFatIndex<=MaxFatIndex(),User::Leave(KErrCorrupt));
    TUint clusterVal;
    if(iOwner->Is16BitFat())
        clusterVal=*(TUint16*)(iCheckFat+PosInBytes(aFatIndex));
    else
        {
        TUint8* pCluster=iCheckFat+PosInBytes(aFatIndex);
        clusterVal=pCluster[0]|(pCluster[1]<<8);
        TBool oddCluster=(aFatIndex)&1;
        if(oddCluster)
            clusterVal>>=4;
        clusterVal&=0xFFF;
        }
    return(clusterVal);
    }


void CCheckFatTable::WriteL(TInt aFatIndex,TInt aValue)
//
// Write a value to the check fat
//
    {
    if(iOwner->Is16BitFat())
        __ASSERT_ALWAYS((TUint32)aFatIndex>=KFatFirstSearchCluster && aFatIndex<=MaxFatIndex() && aValue>=0 && aValue<=0xFFFF,User::Leave(KErrCorrupt));
    else
        __ASSERT_ALWAYS((TUint32)aFatIndex>=KFatFirstSearchCluster && aFatIndex<=MaxFatIndex() && aValue>=0 && aValue<=0xFFF,User::Leave(KErrCorrupt));
    TUint8* p=(TUint8*)(iCheckFat+PosInBytes(aFatIndex));
    if (iOwner->Is16BitFat())
        { 
        *(TUint16*)p=(TUint16)aValue;
        return;
        }
    TUint8 mask=0x0F;
    TBool odd=(aFatIndex)&1;
    TUint8 fatVal;
    if(odd)
        {
        mask<<=4;
        aValue<<=4;
        fatVal=p[0];
        fatVal&=~mask;
        fatVal|=(TUint8)(aValue&0xFF);
        p[0]=fatVal;
        p[1]=(TUint8)(aValue>>8);
        }
    else
        {
        p[0]=(TUint8)(aValue&0xFF);
        fatVal=p[1];
        fatVal&=~mask;
        fatVal|=(TUint8)(aValue>>8);
        p[1]=fatVal;
        }
    return;
    }
    

TBool CCheckFatTable::GetNextClusterL(TInt& aCluster) const
//
// Get the next cluster in the chain from the check fat.
//
    {
    __PRINT(_L("CCheckFatTable::GetNextClusterL"));
    TBool ret;
    TInt nextCluster=ReadL(aCluster);
    if (iOwner->Is16BitFat())
        ret=!IsEof16Bit(nextCluster);
    else
        ret=!IsEof12Bit(nextCluster);
    if (ret)
        aCluster=nextCluster;
    return(ret);
    }

void CCheckFatTable::WriteFatEntryEofFL(TInt aCluster)
//
// Write EOF to aCluster
//
    {
    __PRINT(_L("CCheckFatTable::WriteFatEntryEofF"));
    if (iOwner->Is16BitFat())
        WriteL(aCluster,EOF_16Bit);
    else
        WriteL(aCluster,EOF_12Bit);
    }