// Copyright (c) 1995-2009 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:

//

//  Collection of common constants, utility functions, etc. for the file server and file systems.

//  Definitions here must be filesystem-agnostic, i.e. generic enougs to be used by every file system

//

//  This is the internal file and must not be exported.

/**

    @file

    @internalTechnology

*/

#include "bit_vector.h"

//#######################################################################################################################################

//#   RBitVector class implementation

//#######################################################################################################################################

const TUint32 K_FFFF = 0xFFFFFFFF; //-- all one bits, beware rigth shifts of signed integers!

RBitVector::RBitVector()

          :iNumBits(0), ipData(NULL), iNumWords(0)

    {

    }

RBitVector::~RBitVector()

    {

    Close();

    }

/**

    Panics.

    @param aPanicCode   a panic code

*/

void RBitVector::Panic(TPanicCode aPanicCode) const

    {

    _LIT(KPanicCat,"RBitVector");

    User::Panic(KPanicCat, aPanicCode);

    }

/** explicitly closes the object and deallocates memory */

void RBitVector::Close()

    {

    iNumBits = 0;

    iNumWords =0;

    User::Free(ipData);

    ipData = NULL;

    }

//-----------------------------------------------------------------------------

/**

    Comparison perator.

    @param  aRhs a vector to compate with.

    @panic ESizeMismatch in the case of different vector sizes

*/

TBool RBitVector::operator==(const RBitVector& aRhs) const

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    __ASSERT_ALWAYS(iNumBits == aRhs.iNumBits, Panic(ESizeMismatch));

    if(!iNumBits)

        return ETrue; //-- comparing 0-lenght arrays

    if(this == &aRhs)

        {//-- comparing with itself, potential source of errors

        ASSERT(0);

        return ETrue; 

        }

    if(iNumWords >= 1)

        {

        const TUint32 cntBytes = (iNumBits >> 5) << 2; //-- bytes to compare

        if(memcompare((const TUint8*)ipData, cntBytes, (const TUint8*)aRhs.ipData, cntBytes))

            return EFalse;

        }

    const TUint32 bitsRest  = iNumBits & 0x1F;

    if(bitsRest)

        {

        const TUint32 mask = K_FFFF >> (32-bitsRest);

        return ( (ipData[iNumWords-1] & mask) == (aRhs.ipData[iNumWords-1] & mask) );

        }

    return ETrue;

    }

TBool RBitVector::operator!=(const RBitVector& aRhs) const  

    {

    return ! ((*this) == aRhs);

    } 

//-----------------------------------------------------------------------------

/** The same as Create(), but leaves on error */

void RBitVector::CreateL(TUint32 aNumBits)

    {

    User::LeaveIfError(Create(aNumBits));

    }

/**

    Create the vector with the size of aNumBits bits.

    @return system-wide error codes:

        KErrNoMemory    unable to allocate sufficient amount of memory for the array

        KErrInUse       an attempt to call Create() for non-empty vector. Close it first.

        KErrArgument    invalid aNumBits value == 0

*/

TInt RBitVector::Create(TUint32 aNumBits)

    {

    if(ipData)

        return KErrInUse; //-- array is already in use. Close it first.

    if(!aNumBits)

        return KErrArgument;

    //-- memory is allocated by word (32 bit) quiantities

    const TUint32 numWords = (aNumBits >> 5) + ((aNumBits & 0x1F) > 0 ? 1:0);

    ipData = (TUint32*)User::AllocZ(numWords << 2);

    if(!ipData)

        return KErrNoMemory;

    iNumBits  = aNumBits;

    iNumWords = numWords;

    return KErrNone;

    }

/**

    Fill a bit vector with a given bit value

    @param aVal a bit value

*/

void RBitVector::Fill(TBool aVal)

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    memset(ipData, (aVal ? 0xFF : 0x00), iNumWords << 2);

    }

/** Invert all bits in a bit vector */

void RBitVector::Invert()

{

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    for(TUint32 i=0; i<iNumWords; ++i)

        ipData[i] ^= K_FFFF;

}

/**

    Perform "And" operation between 2 vectors. They shall be the same size.

    @param  aRhs a vector from the right hand side

    @panic ESizeMismatch in the case of different vector sizes

*/

void RBitVector::And(const RBitVector& aRhs)

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    __ASSERT_ALWAYS(iNumBits == aRhs.iNumBits, Panic(ESizeMismatch));

    for(TUint32 i=0; i<iNumWords; ++i)

        {

        ipData[i] &= aRhs.ipData[i];

        }

    }

/**

    Perform "Or" operation between 2 vectors. They shall be the same size.    

    @param  aRhs a vector from the right hand side

    @panic ESizeMismatch in the case of different vector sizes

*/

void RBitVector::Or(const RBitVector& aRhs)

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    __ASSERT_ALWAYS(iNumBits == aRhs.iNumBits, Panic(ESizeMismatch));

    for(TUint32 i=0; i<iNumWords; ++i)

        {

        ipData[i] |= aRhs.ipData[i];

        }

    }

/**

    Perform "Xor" operation between 2 vectors. They shall be the same size.    

    @param  aRhs a vector from the right hand side

    @panic ESizeMismatch in the case of different vector sizes

*/

void RBitVector::Xor(const RBitVector& aRhs)

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    __ASSERT_ALWAYS(iNumBits == aRhs.iNumBits, Panic(ESizeMismatch));

    for(TUint32 i=0; i<iNumWords; ++i)

        {

        ipData[i] ^= aRhs.ipData[i];

        }

    }

//-----------------------------------------------------------------------------

/**

    Fill a range from bit number "aIndexFrom" to "aIndexTo" inclusively with the value of aVal

    @param  aIndexFrom  start bit number (inclusive)

    @param  aIndexTo    end bit number (inclusive)

    @param  aVal        the value to be used to fill the range (0s or 1s)

*/

void RBitVector::Fill(TUint32 aIndexFrom, TUint32 aIndexTo, TBool aVal)

    {

    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));

    //-- swap indexes if they are not in order

    if(aIndexFrom > aIndexTo)

        {

        const TUint32 tmp = aIndexFrom;

        aIndexFrom = aIndexTo;

        aIndexTo = tmp;

        }

    __ASSERT_ALWAYS((aIndexFrom < iNumBits) && (aIndexTo < iNumBits), Panic(EIndexOutOfRange));

    const TUint32 wordStart = WordNum(aIndexFrom);

    const TUint32 wordTo    = WordNum(aIndexTo);

    if(aVal)

        {//-- filling a range with '1'

        TUint32 shift = BitInWord(aIndexFrom);

        const TUint32 mask1 = (K_FFFF >> shift) << shift;

        TUint32 mask2 = K_FFFF;

        shift = 1+BitInWord(aIndexTo);

        if(shift < 32)

            {

            mask2 = ~((mask2 >> shift) << shift);

            }

        if(wordTo == wordStart)

            {//-- a special case, filling is in the same word

            ipData[wordStart] |= (mask1 & mask2);

            }

        else

            {

            ipData[wordStart] |= mask1; 

            ipData[wordTo]    |= mask2;

            const TUint32 wholeWordsBetween = wordTo - wordStart - 1; //-- whole words that can be bulk filled

            if(wholeWordsBetween)

                memset(ipData+wordStart+1, 0xFF, wholeWordsBetween << 2);

            }

        }

    else

        {//-- filling a range with '0'

        TUint32 shift = BitInWord(aIndexFrom);

        const TUint32 mask1 = ~((K_FFFF >> shift) << shift);

        TUint32 mask2 = 0;

        shift = 1+BitInWord(aIndexTo);

        if(shift < 32)

            {

            mask2 = ((K_FFFF >> shift) << shift);

            }

        if(wordTo == wordStart)

            {//-- a special case, filling is in the same word

            ipData[wordStart] &= (mask1 | mask2);

            }

        else

            {

            ipData[wordStart] &= mask1; 

            ipData[wordTo]    &= mask2;

            const TUint32 wholeWordsBetween = wordTo - wordStart - 1; //-- whole words that can be bulk filled

            if(wholeWordsBetween)

                memset(ipData+wordStart+1, 0x00, wholeWordsBetween << 2);

            }

        }

    }

//-----------------------------------------------------------------------------

/**

    Search for a specified bit value ('0' or '1') in the vector from the given position.

    @param  aStartPos   zero-based index; from this position the search will start. This position isn't included to the search.

                        On return may contain a new position if the specified bit is found in specified direction.

    @param  aBitVal     zero or non-zero bit to search.

    @param  aDir        Specifies the search direction

    @return ETrue if the specified bit value is found; aStartPos gets updated.

            EFalse otherwise.

*/

TBool RBitVector::Find(TUint32& aStartPos, TBool aBitVal, TFindDirection aDir) const

    {

    __ASSERT_ALWAYS(aStartPos < iNumBits, Panic(EIndexOutOfRange));

    ASSERT(iNumWords && ipData);

    switch(aDir)

        {

        case ERight:    //-- Search from the given position to the right

            return FindToRight(aStartPos, aBitVal);

        case ELeft:     //-- Search from the given position to the left (towards lower index)

            return FindToLeft(aStartPos, aBitVal);

        case ENearestL: //-- Search for the nearest value in both directions starting from left

            return FindNearest(aStartPos, aBitVal, ETrue);

        case ENearestR: //-- Search for the nearest value in both directions starting from right

            return FindNearest(aStartPos, aBitVal, EFalse);

        default:

            Panic(EWrondFindDirection);

            return EFalse;

        };

    }

//-----------------------------------------------------------------------------

/**

    Internal method to look for a given bit value in the right direction.

    see TBool RBitVector::Find(...)

*/

TBool RBitVector::FindToRight(TUint32& aStartPos, TBool aBitVal) const

    {

    if(aStartPos >= iNumBits-1)

        return EFalse; //-- no way to the right

    const TUint32 startPos = aStartPos+1;

    const TUint32 fInvert = aBitVal ? 0 : K_FFFF; //-- invert everything if we are looking for '0' bit

    TUint32 wordNum = WordNum(startPos);

    TUint32 val = ipData[wordNum] ^ fInvert;

    if(wordNum == iNumWords-1)

        {//-- process the last word in the array, some higher bits might not belong to the bit vector

        val = MaskLastWord(val);

        }

    const TUint32 shift = BitInWord(startPos);

    val = (val >> shift) << shift; //-- mask unused low bits

    if(val)

        {//-- there are '1' bits in the current word

        goto found;

        }

    else

        {//-- search in higher words

        wordNum++;

        while(iNumWords-wordNum > 1)

            {

            val = ipData[wordNum] ^ fInvert;

            if(val)

                goto found;

            wordNum++;

            }

        if(wordNum == iNumWords-1)

            {//-- process the last word in the array, some higher bith might not belong to the bit vector

            val = ipData[wordNum] ^ fInvert;

            val = MaskLastWord(val);

            if(val)

                goto found;

            }

        }

    return EFalse; //-- haven't found anything

  found:

    val &= (~val+1); //-- select rightmost bit

    aStartPos = (wordNum << 5)+Log2(val);

    return ETrue;

    }

//-----------------------------------------------------------------------------

/**

    Internal method to look for a given bit value in the left direction.

    see TBool RBitVector::Find(...)

*/

TBool RBitVector::FindToLeft(TUint32& aStartPos, TBool aBitVal) const

{

    if(!aStartPos)

        return EFalse; //-- no way to the left

    const TUint32 startPos=aStartPos-1;

    const TUint32 fInvert = aBitVal ? 0 : K_FFFF; //-- invert everything if we are looking for '0' bit

    TUint32 wordNum = WordNum(startPos);

    TUint32 val = ipData[wordNum] ^ fInvert;

    const TUint32 shift = 31-(BitInWord(startPos));

    val = (val << shift) >> shift; //-- mask unused high bits

    if(val)

    {//-- there are '1' bits in the current word

        goto found;

    }

    else

    {//-- search in the lower words

        while(wordNum)

        {

            wordNum--;

            val=ipData[wordNum] ^ fInvert;

            if(val)

                goto found;

        }

    }

    return EFalse; //-- nothing found

 found:

    aStartPos = (wordNum << 5)+Log2(val);

    return ETrue;

}

//-----------------------------------------------------------------------------

/**

    Internal method to look for a given bit value in the both directions.

    see TBool RBitVector::Find(...)

*/

TBool RBitVector::FindNearest(TUint32& aStartPos, TBool aBitVal, TBool aToLeft) const

{

    if(iNumBits < 2)

        return EFalse;

    if(aStartPos == 0)

        return FindToRight(aStartPos, aBitVal);

    if(aStartPos == iNumBits-1)

        return FindToLeft(aStartPos, aBitVal);

    const TUint32 fInvert = aBitVal ? 0 : K_FFFF; //-- invert everything if we are looking for '0' bit

    TUint32 wordNum = WordNum(aStartPos);

    TUint32 l_Idx; //-- index of the word to the left

    TUint32 r_Idx; //-- index of the word to the right

    l_Idx = r_Idx = wordNum;

    TBool   noWayLeft  = (wordNum == 0);            //-- if we are in the first word

    TBool   noWayRight = (wordNum == iNumWords-1);  //-- if we are in the last word

    //-- look in the current word first

    TUint32 val = ipData[wordNum] ^ fInvert;

    if(noWayRight)

    {   //-- this is the last word in the array, mask unused high bits in the last word

        val = MaskLastWord(val);

    }

    const TUint32 bitPos = aStartPos & 0x1F;

    val &= ~(1<<bitPos); //-- mask the bit at current position

    if(val == 0)

    {//-- no '1' bits in the current word

        noWayLeft  = ItrLeft(l_Idx);

        noWayRight = ItrRight(r_Idx);

    }

    else if(bitPos == 0)

    {

        noWayLeft = ItrLeft(l_Idx); //-- move to the previous word

    }

    else if(bitPos == 31)

    {

        noWayRight = ItrRight(r_Idx); //-- move to the next word

    }

    else

    {//-- look in the current word, in both halves to the left and right from the start position

        const TUint32 shift1 = 32-bitPos;

        const TUint32 partLo = (val << shift1) >> shift1; //-- towards lower bits

        const TUint32 shift2 = bitPos+1;

        const TUint32 partHi = (val >> shift2) << shift2; //-- towards higher bits 

        if(partLo && !partHi) //-- only lower part has '1' bits   

        {

            aStartPos = (wordNum << 5)+Log2(partLo);

            return ETrue;

        }

        else if(!partLo && partHi) //-- only higher part has '1' bits

        {

            aStartPos = (wordNum << 5)+Log2( (partHi & (~partHi+1)) );

            return ETrue;

        }

        else if(partLo && partHi) //-- both parts contain '1' bits, select the nearest one

        {

            const TUint32 posL = (wordNum << 5)+Log2(partLo);

            const TUint32 posR = (wordNum << 5)+Log2( (partHi & (~partHi+1)) );

            ASSERT(aStartPos > posL);

            ASSERT(posR > aStartPos);

            const TUint32 distL = aStartPos-posL;

            const TUint32 distR = posR-aStartPos;

            if(distL < distR)

            {

                aStartPos = posL;

                return ETrue;

            }

            else if(distL > distR)

            {