userlibandfileserver/fileserver/sfat32/sl_utl.cpp
changeset 15 4122176ea935
child 33 0173bcd7697c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/userlibandfileserver/fileserver/sfat32/sl_utl.cpp	Mon Dec 21 16:14:42 2009 +0000
@@ -0,0 +1,886 @@
+// Copyright (c) 1996-2009 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:
+//
+
+#include "sl_std.h"
+
+//-----------------------------------------------------------------------------
+/**
+    Removes trailing dots from aName.
+    @return new string descriptor that may have its length adjusted
+*/
+TPtrC RemoveTrailingDots(const TDesC& aName)
+{
+    TInt len = aName.Length();
+    
+    while(len > 0)
+    {
+        if(aName[len-1] == '.')
+            len--;
+        else
+            break;
+    }
+
+    TPtrC ptrNoDots(aName.Ptr(), len);
+    return ptrNoDots;
+}
+
+
+TUint32 Log2(TUint32 aVal)
+{
+    __ASSERT_COMPILE(sizeof(TUint32) == 4);
+    ASSERT(aVal);
+
+    TUint32 bitPos=31;
+
+    if(!(aVal >> 16)) {bitPos-=16; aVal<<=16;}
+    if(!(aVal >> 24)) {bitPos-=8;  aVal<<=8 ;}
+    if(!(aVal >> 28)) {bitPos-=4;  aVal<<=4 ;}
+    if(!(aVal >> 30)) {bitPos-=2;  aVal<<=2 ;}
+    if(!(aVal >> 31)) {bitPos-=1;}
+    
+    return bitPos;
+}
+
+
+TTime DosTimeToTTime(TInt aDosTime,TInt aDosDate)
+//
+//	Deciphers the dos time/date entry information and converts to TTime
+//
+	{
+	TInt secMask=0x1F;
+	TInt minMask=0x07E0;
+	TInt hrMask=0xF800;
+	TInt dayMask=0x1F;
+	TInt monthMask=0x01E0;
+	TInt yearMask=0xFE00;
+
+	TInt secs=(aDosTime&secMask)*2;
+	TInt mins=(aDosTime&minMask)>>5;
+	TInt hrs=(aDosTime&hrMask)>>11;
+	TInt days=(aDosDate&dayMask)-1;
+	TMonth months=(TMonth)(((aDosDate&monthMask)>>5)-1);
+	TInt years=((aDosDate&yearMask)>>9)+1980;
+	
+	TDateTime datetime;
+	TInt ret=datetime.Set(years,months,days,hrs,mins,secs,0);
+	if (ret==KErrNone)
+		return(TTime(datetime));
+	return(TTime(0));
+	}
+
+TInt DosTimeFromTTime(const TTime& aTime)
+//
+// Converts a TTime to a dos time
+//
+	{
+	TDateTime dateTime=aTime.DateTime();
+	TInt dosSecs=dateTime.Second()/2;
+	TInt dosMins=dateTime.Minute()<<5;
+	TInt dosHrs=dateTime.Hour()<<11;
+	return dosSecs|dosMins|dosHrs;
+	}
+
+TInt DosDateFromTTime(const TTime& aTime)
+//
+// Converts a TTime to a dos date
+//
+	{
+
+	TDateTime dateTime=aTime.DateTime();
+	TInt dosDays=dateTime.Day()+1;
+	TInt dosMonths=(dateTime.Month()+1)<<5;
+	TInt dosYears=(dateTime.Year()-1980)<<9;
+	return dosDays|dosMonths|dosYears;
+	}
+
+TBuf8<12> DosNameToStdFormat(const TDesC8& aDosName)
+//
+// Converts xxx.yyy to standard format aaaaaaaayyy
+//
+	{
+
+	__ASSERT_DEBUG(aDosName.Length()>=0 && aDosName.Length()<=12,Fault(EFatBadDosFormatName));
+	TBuf8<12> result;
+	Mem::Fill((TUint8*)result.Ptr(),result.MaxSize(),' ');
+	TInt dotPos=aDosName.Locate('.');
+	if (dotPos==KErrNotFound)
+		{
+		result=aDosName;
+		result.SetLength(11);
+		return result;
+		}
+	result=aDosName.Left(dotPos);
+	result.SetLength(11);
+	TPtr8 ext(&result[8],3);
+	ext=aDosName.Right(aDosName.Length()-dotPos-1);
+	return result;
+	}
+
+TBuf8<12> DosNameFromStdFormat(const TDesC8& aStdFormatName)
+//
+// Converts aaaaaaaayyy to dos name format xxx.yyy
+//
+	{
+
+	__ASSERT_DEBUG(aStdFormatName.Length()==11,Fault(EFatBadStdFormatName));
+	TBuf8<12> result;
+	TInt nameLen=aStdFormatName.Locate(' ');
+	if (nameLen>8 || nameLen==KErrNotFound)
+		nameLen=8;
+	result=aStdFormatName.Left(nameLen);
+	TPtrC8 ext(&aStdFormatName[8],3);
+	TInt extLen=ext.Locate(' ');
+	if (extLen)
+		result.Append(TChar('.'));
+	if (extLen==KErrNotFound)
+		extLen=3;
+	result.Append(ext.Left(extLen));
+    if(result.Length() && result[0]==0x05 )
+	    {
+	    result[0]=0xE5;
+	    }
+	return result;
+	}
+
+TInt NumberOfVFatEntries(TInt aNameLength)
+//
+// Return the number of VFat entries required to describe a filename of length aNameLength
+//
+	{
+	TInt numberOfEntries=0;
+	if (aNameLength%KMaxVFatEntryName)
+		aNameLength++;	//	Include a zero terminator
+//	If aNameLength is a exact multiple of KMaxVFatEntryName, don't bother
+//	with a zero terminator - it just adds an unnecessary directory entry		
+	
+	numberOfEntries=(1+(aNameLength/KMaxVFatEntryName));	
+	
+	if (aNameLength%KMaxVFatEntryName)
+		numberOfEntries++;
+	
+	return(numberOfEntries);
+	}
+
+//-----------------------------------------------------------------------------
+/** 
+    Calculate DOS short name checksum
+    @param aShortName short name descriptor (must be at least 11 bytes long)
+    @return checksum
+*/
+TUint8 CalculateShortNameCheckSum(const TDesC8& aShortName)
+    {
+
+    ASSERT(aShortName.Length() >= KFatDirNameSize);
+    const TUint8* pName = aShortName.Ptr();
+
+    const TUint32 w0 = ((const TUint32*)pName)[0];
+    const TUint32 w1 = ((const TUint32*)pName)[1];
+
+    TUint32 chkSum = w0 & 0xFF;
+    
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ((w0 << 16) >> 24));
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ((w0 << 8)  >> 24));
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ( w0 >> 24));
+
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + (w1) & 0xFF);
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ((w1 << 16) >> 24));
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ((w1 << 8)  >> 24));
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + ( w1 >> 24));
+
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + pName[8]);
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + pName[9]);
+    chkSum = (TUint8)(((chkSum<<7) | (chkSum>>1)) + pName[10]);
+
+    return (TUint8)chkSum;
+    }
+
+//-----------------------------------------------------------------------------
+
+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)
+        return ETrue; //-- comparing with itself
+
+    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'
+        
+        //-- if you need this functionality, remove the panic and uncomment the code below.
+
+        Panic(ENotImplemented);
+        
+        /*
+        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)
+            {
+                aStartPos = posR;
+                return ETrue;
+            }
+            else
+            {//-- distL == distR, take into account search priority
+                aStartPos = aToLeft ? posL : posR;
+                return ETrue;
+            }
+        }
+        else //-- (!partLo && !partHi), nothing in the current word
+        {
+            ASSERT(0);
+        }
+
+    }// if(bitPos > 0 && bitPos < 31)
+
+    //-- now we are processing separate words from both sides of the search position
+    for(;;)
+    { 
+        TUint32 wL = ipData[l_Idx] ^ fInvert;
+        TUint32 wR = ipData[r_Idx] ^ fInvert;
+        if(r_Idx == iNumWords-1)
+        {   //-- this is the last word in the array, mask unused high bits in the last word
+            wR = MaskLastWord(wR);
+        }
+
+        if(wL && !wR)
+        {
+            aStartPos = (l_Idx << 5)+Log2(wL);
+            return ETrue;
+        }
+        else if(!wL && wR)
+        {
+            aStartPos = (r_Idx << 5)+Log2( (wR & (~wR+1)) );
+            return ETrue;
+        }
+        else if(wL && wR)
+        {
+            const TUint32 posL = (l_Idx << 5)+Log2(wL);
+            const TUint32 posR = (r_Idx << 5)+Log2( (wR & (~wR+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)
+            {
+                aStartPos = posR;
+                return ETrue;
+            }
+            else
+            {//-- distL == distR, take into account search priority
+                aStartPos = aToLeft ? posL : posR;
+                return ETrue;
+            }
+
+        }//else if(wL && wR)
+
+
+        if(noWayLeft)
+        {
+            aStartPos = r_Idx << 5;
+            return FindToRight(aStartPos, aBitVal);
+        }
+        else
+        {
+            noWayLeft  = ItrLeft(l_Idx);
+        }
+
+        if(noWayRight)
+        {
+            aStartPos = l_Idx << 5;
+            return FindToLeft(aStartPos, aBitVal);
+        }
+        else
+        {    
+            noWayRight = ItrRight(r_Idx);
+        }
+
+   }//for(;;)
+
+    //return EFalse;
+}
+
+//-----------------------------------------------------------------------------
+/**
+    Find out if two vectors are different.
+
+    @param  aRhs        vector to compare with
+    @param  aDiffIndex  if there is a differene, here will be the number of the first different bit
+    @return ETrue if vectors differ, EFalse, if they are identical.
+*/
+TBool RBitVector::Diff(const RBitVector& aRhs, TUint32& aDiffIndex) const
+{
+    __ASSERT_ALWAYS(ipData, Panic(ENotInitialised));
+    __ASSERT_ALWAYS(iNumBits == aRhs.iNumBits, Panic(ESizeMismatch));
+    ASSERT(iNumWords > 0);
+
+    TUint32 diffWord=0;
+    TUint32 wordNum=0;
+
+    //-- compare all but the last word in the array
+    for(wordNum=0; wordNum < iNumWords-1; ++wordNum)
+    {
+        diffWord = ipData[wordNum] ^ aRhs.ipData[wordNum];
+        if(diffWord)
+            break;  //-- found difference
+    }
+
+    //-- process the last word in the array
+    if(!diffWord)
+    {
+        diffWord = MaskLastWord(ipData[wordNum]) ^ MaskLastWord(aRhs.ipData[wordNum]);
+    }
+
+    if(!diffWord)
+        return EFalse; //-- vectors are the same
+
+    //-- calculate the position of the bit that different.
+    diffWord &= (~diffWord+1); //-- select rightmost bit
+    aDiffIndex = (wordNum << 5)+Log2(diffWord);
+    
+    return ETrue;
+}
+//-----------------------------------------------------------------------------
+
+/**
+    Iterate to the left (towards lower index) in the array of words ipData
+
+    @param  aIdx index within ipData array to be decremented; if it's possible to move left, it will be decreased
+    @return ETrue if there is no way left i.e. aIdx is 0. EFalse otherwise and aIdx decreased.
+*/
+TBool RBitVector::ItrLeft(TUint32& aIdx) const
+{
+    if(aIdx == 0)
+        return ETrue;
+    else
+    {
+        aIdx--;
+        return EFalse;
+    }
+}
+
+
+/**
+    Iterate to the right (towards higher index) in the array of words ipData
+
+    @param  aIdx index within ipData array to be incremented; if it's possible to move right, it will be increased
+    @return ETrue if there is no way right i.e. aIdx corresponds to the last word. EFalse otherwise and aIdx increased.
+*/
+TBool RBitVector::ItrRight(TUint32& aIdx) const
+{
+    if(aIdx < iNumWords-1)
+    {
+        aIdx++;
+        return EFalse;
+    }
+    else
+        return ETrue;
+}
+
+
+
+
+
+
+
+