New subject: [ros-diffs] [tkreuzer] 44464: [RTL] Rewrite the rtl bitmap implementation. The old one was a little .... suboptimal. The new one should outperform the old one by several orders of magnitude, especially RtlFindClearBits that was literally searching bit by bit.

8 Dec 2009

What about bsr and bsl?

On 2009-12-07, at 8:02 PM, tkreuzer(a)svn.reactos.org wrote:

...
  Author: tkreuzer
 Date: Tue Dec  8 02:02:36 2009
 New Revision: 44464

 URL: http://svn.reactos.org/svn/reactos?rev=44464&view=rev
 Log:
 [RTL]
 Rewrite the rtl bitmap implementation.
 The old one was a little .... suboptimal. The new one should outperform the old one by
several orders of magnitude, especially RtlFindClearBits that was literally searching bit
by bit.

 Modified:
    trunk/reactos/lib/rtl/bitmap.c
    trunk/reactos/tools/mkhive/mkhive.h
    trunk/reactos/tools/mkhive/rtl.c

 Modified: trunk/reactos/lib/rtl/bitmap.c
 URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/bitmap.c?rev=44464…
 ==============================================================================
 --- trunk/reactos/lib/rtl/bitmap.c [iso-8859-1] (original)
 +++ trunk/reactos/lib/rtl/bitmap.c [iso-8859-1] Tue Dec  8 02:02:36 2009
 @@ -1,8 +1,9 @@
 -/* COPYRIGHT:       See COPYING in the top level directory
 +/*
 + * COPYRIGHT:       See COPYING in the top level directory
  * PROJECT:         ReactOS system libraries
  * FILE:            lib/rtl/bitmap.c
  * PURPOSE:         Bitmap functions
 - * PROGRAMMER:      Eric Kohl
 + * PROGRAMMER:      Timo Kreuzer (timo.kreuzer(a)reactos.org)
  */

 /* INCLUDES *****************************************************************/
 @@ -12,965 +13,749 @@
 #define NDEBUG
 #include <debug.h>

 -/* MACROS *******************************************************************/
 -
 -/* Bits set from LSB to MSB; used as mask for runs < 8 bits */
 -static const BYTE NTDLL_maskBits[8] = { 0, 1, 3, 7, 15, 31, 63, 127 };
 -
 -/* Number of set bits for each value of a nibble; used for counting */
 -static const BYTE NTDLL_nibbleBitCount[16] = {
 -  0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
 +
 +/* DATA *********************************************************************/
 +
 +/* Number of set bits per byte value */
 +static const
 +UCHAR
 +BitCountTable[256] =
 +{
 +    /* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
 +       0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, /* 0x */
 +       1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, /* 1x */
 +       1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, /* 2x */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* 3x */
 +       1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, /* 4x */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* 5x */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* 6c */
 +       3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, /* 7x */
 +       1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, /* 8x */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* 9x */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* Ax */
 +       3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, /* Bx */
 +       2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, /* Cx */
 +       3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, /* Dx */
 +       3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, /* Ex */
 +       4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8  /* Fx */
 };

 -/* First set bit in a nibble; used for determining least significant bit */
 -static const BYTE NTDLL_leastSignificant[16] = {
 -  0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
 -};
 -
 -/* Last set bit in a nibble; used for determining most significant bit */
 -static const signed char NTDLL_mostSignificant[16] = {
 -  -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
 -};
 -
 -/* PRIVATE FUNCTIONS *********************************************************/
 -
 -static
 -int
 -__cdecl
 -NTDLL_RunSortFn(const void *lhs,
 -                const void *rhs)
 -{
 -  if (((const RTL_BITMAP_RUN*)lhs)->NumberOfBits > ((const
RTL_BITMAP_RUN*)rhs)->NumberOfBits)
 +
 +/* PRIVATE FUNCTIONS ********************************************************/
 +
 +static __inline__
 +ULONG
 +RtlpGetLengthOfRunClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG MaxLength)
 +{
 +    ULONG Value, BitPos, Length;
 +    PULONG Buffer, MaxBuffer;
 +
 +    /* Calculate positions */
 +    Buffer = BitMapHeader->Buffer + StartingIndex / 32;
 +    BitPos = StartingIndex & 31;
 +
 +    /* Calculate the maximum length */
 +    MaxLength = min(MaxLength, BitMapHeader->SizeOfBitMap - StartingIndex);
 +    MaxBuffer = Buffer + (BitPos + MaxLength + 31) / 32;
 +
 +    /* Clear the bits that don't belong to this run */
 +    Value = *Buffer++ >> BitPos << BitPos;
 +
 +    /* Skip all clear ULONGs */
 +    while (Value == 0 && Buffer < MaxBuffer)
 +    {
 +        Value = *Buffer++;
 +    }
 +
 +    /* Did we reach the end? */
 +    if (Value == 0)
 +    {
 +        /* Return maximum length */
 +        return MaxLength;
 +    }
 +
 +    /* We hit a set bit, check how many clear bits are left */
 +    BitScanForward(&BitPos, Value);
 +
 +    /* Calculate length up to where we read */
 +    Length = (Buffer - BitMapHeader->Buffer) * 32 - StartingIndex;
 +    Length += BitPos - 32;
 +    
 +    if (Length > BitMapHeader->SizeOfBitMap - StartingIndex)
 +        Length = BitMapHeader->SizeOfBitMap - StartingIndex;
 +
 +    /* The result is guaranteed to be < BitMapHeader->SizeOfBitMap */
 +    return Length;
 +}
 +
 +static __inline__
 +ULONG
 +RtlpGetLengthOfRunSet(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG MaxLength)
 +{
 +    ULONG InvValue, BitPos, Length;
 +    PULONG Buffer, MaxBuffer;
 +
 +    /* Calculate positions */
 +    Buffer = BitMapHeader->Buffer + StartingIndex / 32;
 +    BitPos = StartingIndex & 31;
 +
 +    /* Calculate the maximum length */
 +    MaxLength = min(MaxLength, BitMapHeader->SizeOfBitMap - StartingIndex);
 +    MaxBuffer = Buffer + (BitPos + MaxLength + 31) / 32;
 +
 +    /* Get the inversed value, clear bits that don't belong to the run */
 +    InvValue = ~(*Buffer++) >> BitPos << BitPos;
 +
 +    /* Skip all set ULONGs */
 +    while (InvValue == 0 && Buffer < MaxBuffer)
 +    {
 +        InvValue = ~(*Buffer++);
 +    }
 +
 +    /* Did we reach the end? */
 +    if (InvValue == 0)
 +    {
 +        /* Yes, return maximum */
 +        return MaxLength;
 +    }
 +
 +    /* We hit a clear bit, check how many set bits are left */
 +    BitScanForward(&BitPos, InvValue);
 +
 +    /* Calculate length up to where we read */
 +    Length = (Buffer - BitMapHeader->Buffer) * 32 - StartingIndex;
 +    Length += BitPos - 32;
 +
 +    if (Length > BitMapHeader->SizeOfBitMap - StartingIndex)
 +        Length = BitMapHeader->SizeOfBitMap - StartingIndex;
 +
 +    /* The result is guaranteed to be < BitMapHeader->SizeOfBitMap */
 +    return Length;
 +}
 +
 +
 +/* PUBLIC FUNCTIONS **********************************************************/
 +
 +CCHAR
 +NTAPI
 +RtlFindMostSignificantBit(ULONGLONG Value)
 +{
 +    ULONG Position;
 +
 +    if (BitScanReverse(&Position, Value >> 32))
 +    {
 +        return Position + 32;
 +    }
 +    else if (BitScanReverse(&Position, (ULONG)Value))
 +    {
 +        return Position;
 +    }
 +
     return -1;
 -  return 1;
 -}
 -
 -static
 -ULONG
 -WINAPI
 -NTDLL_FindRuns(PRTL_BITMAP lpBits,
 -               PRTL_BITMAP_RUN lpSeries,
 -               ULONG ulCount,
 -               BOOLEAN bLongest,
 -               ULONG (*fn)(PRTL_BITMAP,ULONG,PULONG))
 -{
 -  BOOL bNeedSort = ulCount > 1 ? TRUE : FALSE;
 -  ULONG ulPos = 0, ulRuns = 0;
 -
 -  if (!ulCount)
 -    return MAXULONG;
 -
 -  while (ulPos < lpBits->SizeOfBitMap)
 -  {
 -    /* Find next set/clear run */
 -    ULONG ulSize, ulNextPos = fn(lpBits, ulPos, &ulSize);
 -
 -    if (ulNextPos == MAXULONG)
 -      break;
 -
 -    if (bLongest && ulRuns == ulCount)
 -    {
 -      /* Sort runs with shortest at end, if they are out of order */
 -      if (bNeedSort)
 -        qsort(lpSeries, ulRuns, sizeof(RTL_BITMAP_RUN), NTDLL_RunSortFn);
 -
 -      /* Replace last run if this one is bigger */
 -      if (ulSize > lpSeries[ulRuns - 1].NumberOfBits)
 -      {
 -        lpSeries[ulRuns - 1].StartingIndex = ulNextPos;
 -        lpSeries[ulRuns - 1].NumberOfBits = ulSize;
 -
 -        /* We need to re-sort the array, _if_ we didn't leave it sorted */
 -        if (ulRuns > 1 && ulSize > lpSeries[ulRuns - 2].NumberOfBits)
 -          bNeedSort = TRUE;
 -      }
 -    }
 -    else
 -    {
 -      /* Append to found runs */
 -      lpSeries[ulRuns].StartingIndex = ulNextPos;
 -      lpSeries[ulRuns].NumberOfBits = ulSize;
 -      ulRuns++;
 -
 -      if (!bLongest && ulRuns == ulCount)
 -        break;
 -    }
 -    ulPos = ulNextPos + ulSize;
 -  }
 -  return ulRuns;
 -}
 -
 -static
 -ULONG
 -NTDLL_FindSetRun(PRTL_BITMAP lpBits,
 -                 ULONG ulStart,
 -                 PULONG lpSize)
 -{
 -  LPBYTE lpOut;
 -  ULONG ulFoundAt = 0, ulCount = 0;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);
 -
 -  while (1)
 -  {
 -    /* Check bits in first byte */
 -    const BYTE bMask = (0xff << (ulStart & 7)) & 0xff;
 -    const BYTE bFirst = *lpOut & bMask;
 -
 -    if (bFirst)
 -    {
 -      /* Have a set bit in first byte */
 -      if (bFirst != bMask)
 -      {
 -        /* Not every bit is set */
 -        ULONG ulOffset;
 -
 -        if (bFirst & 0x0f)
 -          ulOffset = NTDLL_leastSignificant[bFirst & 0x0f];
 -        else
 -          ulOffset = 4 + NTDLL_leastSignificant[bFirst >> 4];
 -        ulStart += ulOffset;
 -        ulFoundAt = ulStart;
 -        for (;ulOffset < 8; ulOffset++)
 -        {
 -          if (!(bFirst & (1 << ulOffset)))
 -          {
 -            *lpSize = ulCount;
 -            return ulFoundAt; /* Set from start, but not until the end */
 -          }
 -          ulCount++;
 -          ulStart++;
 -        }
 -        /* Set to the end - go on to count further bits */
 -        lpOut++;
 -        break;
 -      }
 -      /* every bit from start until the end of the byte is set */
 -      ulFoundAt = ulStart;
 -      ulCount = 8 - (ulStart & 7);
 -      ulStart = (ulStart & ~7u) + 8;
 -      lpOut++;
 -      break;
 -    }
 -    ulStart = (ulStart & ~7u) + 8;
 -    lpOut++;
 -    if (ulStart >= lpBits->SizeOfBitMap)
 -      return MAXULONG;
 -  }
 -
 -  /* Count blocks of 8 set bits */
 -  while (*lpOut == 0xff)
 -  {
 -    ulCount += 8;
 -    ulStart += 8;
 -    if (ulStart >= lpBits->SizeOfBitMap)
 -    {
 -      *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
 -      return ulFoundAt;
 -    }
 -    lpOut++;
 -  }
 -
 -  /* Count remaining contiguous bits, if any */
 -  if (*lpOut & 1)
 -  {
 -    ULONG ulOffset = 0;
 -
 -    for (;ulOffset < 7u; ulOffset++)
 -    {
 -      if (!(*lpOut & (1 << ulOffset)))
 -        break;
 -      ulCount++;
 -    }
 -  }
 -  *lpSize = ulCount;
 -  return ulFoundAt;
 -}
 -
 -static
 -ULONG
 -NTDLL_FindClearRun(PRTL_BITMAP lpBits,
 -                   ULONG ulStart,
 -                   PULONG lpSize)
 -{
 -  LPBYTE lpOut;
 -  ULONG ulFoundAt = 0, ulCount = 0;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)lpBits->Buffer) + (ulStart >> 3u);
 -
 -  while (1)
 -  {
 -    /* Check bits in first byte */
 -    const BYTE bMask = (0xff << (ulStart & 7)) & 0xff;
 -    const BYTE bFirst = (~*lpOut) & bMask;
 -
 -    if (bFirst)
 -    {
 -      /* Have a clear bit in first byte */
 -      if (bFirst != bMask)
 -      {
 -        /* Not every bit is clear */
 -        ULONG ulOffset;
 -
 -        if (bFirst & 0x0f)
 -          ulOffset = NTDLL_leastSignificant[bFirst & 0x0f];
 -        else
 -          ulOffset = 4 + NTDLL_leastSignificant[bFirst >> 4];
 -        ulStart += ulOffset;
 -        ulFoundAt = ulStart;
 -        for (;ulOffset < 8; ulOffset++)
 -        {
 -          if (!(bFirst & (1 << ulOffset)))
 -          {
 -            *lpSize = ulCount;
 -            return ulFoundAt; /* Clear from start, but not until the end */
 -          }
 -          ulCount++;
 -          ulStart++;
 -        }
 -        /* Clear to the end - go on to count further bits */
 -        lpOut++;
 -        break;
 -      }
 -      /* Every bit from start until the end of the byte is clear */
 -      ulFoundAt = ulStart;
 -      ulCount = 8 - (ulStart & 7);
 -      ulStart = (ulStart & ~7u) + 8;
 -      lpOut++;
 -      break;
 -    }
 -    ulStart = (ulStart & ~7u) + 8;
 -    lpOut++;
 -    if (ulStart >= lpBits->SizeOfBitMap)
 -      return MAXULONG;
 -  }
 -
 -  /* Count blocks of 8 clear bits */
 -  while (!*lpOut)
 -  {
 -    ulCount += 8;
 -    ulStart += 8;
 -    if (ulStart >= lpBits->SizeOfBitMap)
 -    {
 -      *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
 -      return ulFoundAt;
 -    }
 -    lpOut++;
 -  }
 -
 -  /* Count remaining contiguous bits, if any */
 -  if (!(*lpOut & 1))
 -  {
 -    ULONG ulOffset = 0;
 -
 -    for (;ulOffset < 7u; ulOffset++)
 -    {
 -      if (*lpOut & (1 << ulOffset))
 -        break;
 -      ulCount++;
 -    }
 -  }
 -  *lpSize = ulCount;
 -  return ulFoundAt;
 -}
 -
 -/* FUNCTIONS ****************************************************************/
 -
 -/*
 - * @implemented
 - */
 +}
 +
 +CCHAR
 +NTAPI
 +RtlFindLeastSignificantBit(ULONGLONG Value)
 +{
 +    ULONG Position;
 +
 +    if (BitScanForward(&Position, (ULONG)Value))
 +    {
 +        return Position;
 +    }
 +    else if (BitScanForward(&Position, Value >> 32))
 +    {
 +        return Position + 32;
 +    }
 +
 +    return -1;
 +}
 +
 VOID
 NTAPI
 -RtlInitializeBitMap(IN PRTL_BITMAP BitMapHeader,
 -                    IN PULONG BitMapBuffer,
 -                    IN ULONG SizeOfBitMap)
 -{
 +RtlInitializeBitMap(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN PULONG BitMapBuffer,
 +    IN ULONG SizeOfBitMap)
 +{
 +    // FIXME: some bugger here!
 +    //ASSERT(SizeOfBitMap > 0);
 +
     /* Setup the bitmap header */
     BitMapHeader->SizeOfBitMap = SizeOfBitMap;
     BitMapHeader->Buffer = BitMapBuffer;
 }

 -/*
 - * @implemented
 - */
 +VOID
 +NTAPI
 +RtlClearAllBits(
 +    IN OUT PRTL_BITMAP BitMapHeader)
 +{
 +    ULONG LengthInUlongs;
 +
 +    LengthInUlongs = (BitMapHeader->SizeOfBitMap + 31) >> 5;
 +    RtlFillMemoryUlong(BitMapHeader->Buffer, LengthInUlongs << 2, 0);
 +}
 +
 +VOID
 +NTAPI
 +RtlSetAllBits(
 +    IN OUT PRTL_BITMAP BitMapHeader)
 +{
 +    ULONG LengthInUlongs;
 +    
 +    LengthInUlongs = (BitMapHeader->SizeOfBitMap + 31) >> 5;
 +    RtlFillMemoryUlong(BitMapHeader->Buffer, LengthInUlongs << 2, ~0);
 +}
 +
 +VOID
 +NTAPI
 +RtlClearBit(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG BitNumber)
 +{
 +    ASSERT(BitNumber <= BitMapHeader->SizeOfBitMap);
 +    BitMapHeader->Buffer[BitNumber >> 5] &= ~(1 << (BitNumber &
31));
 +}
 +
 +VOID
 +NTAPI
 +RtlSetBit(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG BitNumber)
 +{
 +    ASSERT(BitNumber <= BitMapHeader->SizeOfBitMap);
 +    BitMapHeader->Buffer[BitNumber >> 5] |= (1 << (BitNumber & 31));
 +}
 +
 +VOID
 +NTAPI
 +RtlClearBits(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG NumberToClear)
 +{
 +    ULONG Bits, Mask;
 +    PULONG Buffer;
 +
 +    ASSERT(StartingIndex + NumberToClear <= BitMapHeader->SizeOfBitMap);
 +
 +    /* Calculate buffer start and first bit index */
 +    Buffer = &BitMapHeader->Buffer[StartingIndex >> 5];
 +    Bits = StartingIndex & 31;
 +
 +    /* Are we unaligned? */
 +    if (Bits)
 +    {
 +        /* Create an inverse mask by shifting MAXULONG */
 +        Mask = MAXULONG << Bits;
 +
 +        /* This is what's left in the first ULONG */
 +        Bits = 32 - Bits;
 +
 +        /* Even less bits to clear? */
 +        if (NumberToClear < Bits)
 +        {
 +            /* Calculate how many bits are left */
 +            Bits -= NumberToClear;
 +
 +            /* Fixup the mask on the high side */
 +            Mask = Mask << Bits >> Bits;
 +
 +            /* Clear bits and return */
 +            *Buffer &= ~Mask;
 +            return;
 +        }
 +
 +        /* Clear bits */
 +        *Buffer &= ~Mask;
 +
 +        /* Update buffer and left bits */
 +        Buffer++;
 +        NumberToClear -= Bits;
 +    }
 +
 +    /* Clear all full ULONGs */
 +    RtlFillMemoryUlong(Buffer, NumberToClear >> 3, 0);
 +    Buffer += NumberToClear >> 5;
 +
 +    /* Clear what's left */
 +    NumberToClear &= 31;
 +    Mask = MAXULONG << NumberToClear;
 +    *Buffer &= Mask;
 +}
 +
 +VOID
 +NTAPI
 +RtlSetBits(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG NumberToSet)
 +{
 +    ULONG Bits, Mask;
 +    PULONG Buffer;
 +
 +    ASSERT(StartingIndex + NumberToSet <= BitMapHeader->SizeOfBitMap);
 +
 +    /* Calculate buffer start and first bit index */
 +    Buffer = &BitMapHeader->Buffer[StartingIndex >> 5];
 +    Bits = StartingIndex & 31;
 +
 +    /* Are we unaligned? */
 +    if (Bits)
 +    {
 +        /* Create a mask by shifting MAXULONG */
 +        Mask = MAXULONG << Bits;
 +
 +        /* This is what's left in the first ULONG */
 +        Bits = 32 - Bits;
 +
 +        /* Even less bits to clear? */
 +        if (NumberToSet < Bits)
 +        {
 +            /* Calculate how many bits are left */
 +            Bits -= NumberToSet;
 +
 +            /* Fixup the mask on the high side */
 +            Mask = Mask << Bits >> Bits;
 +
 +            /* Set bits and return */
 +            *Buffer |= Mask;
 +            return;
 +        }
 +
 +        /* Set bits */
 +        *Buffer |= Mask;
 +
 +        /* Update buffer and left bits */
 +        Buffer++;
 +        NumberToSet -= Bits;
 +    }
 +
 +    /* Set all full ULONGs */
 +    RtlFillMemoryUlong(Buffer, NumberToSet >> 3, MAXULONG);
 +    Buffer += NumberToSet >> 5;
 +
 +    /* Set what's left */
 +    NumberToSet &= 31;
 +    Mask = MAXULONG << NumberToSet;
 +    *Buffer |= ~Mask;
 +}
 +
 BOOLEAN
 NTAPI
 -RtlAreBitsClear(IN PRTL_BITMAP BitMapHeader,
 -                IN ULONG StartingIndex,
 -                IN ULONG Length)
 -{
 -  LPBYTE lpOut;
 -  ULONG ulRemainder;
 -
 -  if (!BitMapHeader || !Length ||
 -      StartingIndex >= BitMapHeader->SizeOfBitMap ||
 -      Length > BitMapHeader->SizeOfBitMap - StartingIndex)
 -    return FALSE;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)BitMapHeader->Buffer) + (StartingIndex >> 3u);
 -
 -  /* Check bits in first byte, if StartingIndex isn't a byte boundary */
 -  if (StartingIndex & 7)
 -  {
 -    if (Length > 7)
 -    {
 -      /* Check from start bit to the end of the byte */
 -      if (*lpOut & ((0xff << (StartingIndex & 7)) & 0xff))
 -        return FALSE;
 -      lpOut++;
 -      Length -= (8 - (StartingIndex & 7));
 -    }
 -    else
 -    {
 -      /* Check from the start bit, possibly into the next byte also */
 -      USHORT initialWord = NTDLL_maskBits[Length] << (StartingIndex & 7);
 -
 -      if (*lpOut & (initialWord & 0xff))
 -        return FALSE;
 -      if ((initialWord & 0xff00) && (lpOut[1] & (initialWord >>
8)))
 -        return FALSE;
 -      return TRUE;
 -    }
 -  }
 -
 -  /* Check bits in blocks of 8 bytes */
 -  ulRemainder = Length & 7;
 -  Length >>= 3;
 -  while (Length--)
 -  {
 -    if (*lpOut++)
 -      return FALSE;
 -  }
 -
 -  /* Check remaining bits, if any */
 -  if (ulRemainder && *lpOut & NTDLL_maskBits[ulRemainder])
 -    return FALSE;
 -  return TRUE;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -BOOLEAN NTAPI
 -RtlAreBitsSet(PRTL_BITMAP BitMapHeader,
 -	      ULONG StartingIndex,
 -	      ULONG Length)
 -{
 -  LPBYTE lpOut;
 -  ULONG ulRemainder;
 -
 -
 -  if (!BitMapHeader || !Length ||
 -      StartingIndex >= BitMapHeader->SizeOfBitMap ||
 -      Length > BitMapHeader->SizeOfBitMap - StartingIndex)
 -    return FALSE;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)BitMapHeader->Buffer) + (StartingIndex >> 3u);
 -
 -  /* Check bits in first byte, if StartingIndex isn't a byte boundary */
 -  if (StartingIndex & 7)
 -  {
 -    if (Length > 7)
 -    {
 -      /* Check from start bit to the end of the byte */
 -      if ((*lpOut &
 -          ((0xff << (StartingIndex & 7))) & 0xff) != ((0xff <<
(StartingIndex & 7) & 0xff)))
 -        return FALSE;
 -      lpOut++;
 -      Length -= (8 - (StartingIndex & 7));
 -    }
 -    else
 -    {
 -      /* Check from the start bit, possibly into the next byte also */
 -      USHORT initialWord = NTDLL_maskBits[Length] << (StartingIndex & 7);
 -
 -      if ((*lpOut & (initialWord & 0xff)) != (initialWord & 0xff))
 -        return FALSE;
 -      if ((initialWord & 0xff00) &&
 -          ((lpOut[1] & (initialWord >> 8)) != (initialWord >> 8)))
 -        return FALSE;
 -      return TRUE;
 -    }
 -  }
 -
 -  /* Check bits in blocks of 8 bytes */
 -  ulRemainder = Length & 7;
 -  Length >>= 3;
 -  while (Length--)
 -  {
 -    if (*lpOut++ != 0xff)
 -      return FALSE;
 -  }
 -
 -  /* Check remaining bits, if any */
 -  if (ulRemainder &&
 -      (*lpOut & NTDLL_maskBits[ulRemainder]) != NTDLL_maskBits[ulRemainder])
 -    return FALSE;
 -  return TRUE;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -VOID NTAPI
 -RtlClearAllBits(IN OUT PRTL_BITMAP BitMapHeader)
 -{
 -    memset(BitMapHeader->Buffer, 0, ((BitMapHeader->SizeOfBitMap + 31) & ~31)
>> 3);
 -}
 -
 -/*
 - * @implemented
 - */
 -VOID
 -NTAPI
 -RtlClearBit(PRTL_BITMAP BitMapHeader,
 -            ULONG BitNumber)
 -{
 -    PUCHAR Ptr;
 -
 -    if (BitNumber >= BitMapHeader->SizeOfBitMap) return;
 -
 -    Ptr = (PUCHAR)BitMapHeader->Buffer + (BitNumber / 8);
 -    *Ptr &= ~(1 << (BitNumber % 8));
 -}
 -
 -/*
 - * @implemented
 - */
 -VOID
 -NTAPI
 -RtlClearBits(IN PRTL_BITMAP BitMapHeader,
 -             IN ULONG StartingIndex,
 -             IN ULONG NumberToClear)
 -{
 -  LPBYTE lpOut;
 -
 -  if (!BitMapHeader || !NumberToClear ||
 -      StartingIndex >= BitMapHeader->SizeOfBitMap ||
 -      NumberToClear > BitMapHeader->SizeOfBitMap - StartingIndex)
 -    return;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)BitMapHeader->Buffer) + (StartingIndex >> 3u);
 -
 -  /* Clear bits in first byte, if StartingIndex isn't a byte boundary */
 -  if (StartingIndex & 7)
 -  {
 -    if (NumberToClear > 7)
 -    {
 -      /* Clear from start bit to the end of the byte */
 -      *lpOut++ &= ~(0xff << (StartingIndex & 7));
 -      NumberToClear -= (8 - (StartingIndex & 7));
 -    }
 -    else
 -    {
 -      /* Clear from the start bit, possibly into the next byte also */
 -      USHORT initialWord = ~(NTDLL_maskBits[NumberToClear] << (StartingIndex &
7));
 -
 -      *lpOut++ &= (initialWord & 0xff);
 -      *lpOut &= (initialWord >> 8);
 -      return;
 -    }
 -  }
 -
 -  /* Clear bits (in blocks of 8) on whole byte boundaries */
 -  if (NumberToClear >> 3)
 -  {
 -    memset(lpOut, 0, NumberToClear >> 3);
 -    lpOut = lpOut + (NumberToClear >> 3);
 -  }
 -
 -  /* Clear remaining bits, if any */
 -  if (NumberToClear & 0x7)
 -    *lpOut &= ~NTDLL_maskBits[NumberToClear & 0x7];
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindClearBits(PRTL_BITMAP BitMapHeader,
 -		 ULONG NumberToFind,
 -		 ULONG HintIndex)
 -{
 -  ULONG ulPos, ulEnd;
 -
 -  if (!BitMapHeader || !NumberToFind || NumberToFind >
BitMapHeader->SizeOfBitMap)
 +RtlTestBit(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG BitNumber)
 +{
 +    ASSERT(BitNumber < BitMapHeader->SizeOfBitMap);
 +    return (BitMapHeader->Buffer[BitNumber >> 5] >> (BitNumber & 31))
& 1;
 +}
 +
 +BOOLEAN
 +NTAPI
 +RtlAreBitsClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG Length)
 +{
 +    return RtlpGetLengthOfRunClear(BitMapHeader, StartingIndex, Length) >= Length;
 +}
 +
 +BOOLEAN
 +NTAPI
 +RtlAreBitsSet(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG StartingIndex,
 +    IN ULONG Length)
 +{
 +    return RtlpGetLengthOfRunSet(BitMapHeader, StartingIndex, Length) >= Length;
 +}
 +
 +ULONG
 +NTAPI
 +RtlNumberOfSetBits(
 +    IN PRTL_BITMAP BitMapHeader)
 +{
 +    PUCHAR Byte, MaxByte;
 +    ULONG BitCount = 0;
 +
 +    Byte = (PUCHAR)BitMapHeader->Buffer;
 +    MaxByte = Byte + (BitMapHeader->SizeOfBitMap + 7) / 8;
 +
 +    do
 +    {
 +        BitCount += BitCountTable[*Byte++];
 +    }
 +    while (Byte <= MaxByte);
 +
 +    return BitCount;
 +}
 +
 +ULONG
 +NTAPI
 +RtlNumberOfClearBits(
 +    IN PRTL_BITMAP BitMapHeader)
 +{
 +    /* Do some math */
 +    return BitMapHeader->SizeOfBitMap - RtlNumberOfSetBits(BitMapHeader);
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindClearBits(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG NumberToFind,
 +    IN ULONG HintIndex)
 +{
 +    ULONG CurrentBit, CurrentLength;
 +
 +    /* Check for valid parameters */
 +    if (!BitMapHeader || NumberToFind > BitMapHeader->SizeOfBitMap)
 +    {
 +        return MAXULONG;
 +    }
 +
 +    /* Check for trivial case */
 +    if (NumberToFind == 0)
 +    {
 +        return HintIndex;
 +    }
 +
 +    /* Start with hint index, length is 0 */
 +    CurrentBit = HintIndex;
 +    CurrentLength = 0;
 +
 +    /* Loop until something is found or the end is reached */
 +    while (CurrentBit + NumberToFind < BitMapHeader->SizeOfBitMap)
 +    {
 +        ULONG test;
 +        /* Search for the next clear run, by skipping a set run */
 +        test = RtlpGetLengthOfRunSet(BitMapHeader,
 +                                            CurrentBit,
 +                                            MAXULONG);
 +        CurrentBit += test;
 +
 +        /* Get length of the clear bit run */
 +        CurrentLength = RtlpGetLengthOfRunClear(BitMapHeader,
 +                                                CurrentBit,
 +                                                NumberToFind);
 +
 +        /* Is this long enough? */
 +        if (CurrentLength >= NumberToFind)
 +        {
 +            /* It is */
 +            return CurrentBit;
 +        }
 +
 +        CurrentBit += CurrentLength;
 +    }
 +
 +    /* Nothing found */
     return MAXULONG;
 -
 -  ulEnd = BitMapHeader->SizeOfBitMap;
 -
 -  if (HintIndex + NumberToFind > BitMapHeader->SizeOfBitMap)
 -    HintIndex = 0;
 -
 -  ulPos = HintIndex;
 -
 -  while (ulPos < ulEnd)
 -  {
 -    /* FIXME: This could be made a _lot_ more efficient */
 -    if (RtlAreBitsClear(BitMapHeader, ulPos, NumberToFind))
 -      return ulPos;
 -
 -    /* Start from the beginning if we hit the end and started from HintIndex */
 -    if (ulPos == ulEnd - 1 && HintIndex)
 -    {
 -      ulEnd = HintIndex;
 -      ulPos = HintIndex = 0;
 -    }
 -    else
 -      ulPos++;
 -  }
 -  return MAXULONG;
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindClearRuns(PRTL_BITMAP BitMapHeader,
 -		 PRTL_BITMAP_RUN RunArray,
 -		 ULONG SizeOfRunArray,
 -		 BOOLEAN LocateLongestRuns)
 -{
 -    return NTDLL_FindRuns(BitMapHeader, RunArray, SizeOfRunArray, LocateLongestRuns,
NTDLL_FindClearRun);
 -}
 -
 -/*
 - * @unimplemented
 - */
 -ULONG NTAPI
 -RtlFindLastBackwardRunClear(IN PRTL_BITMAP BitMapHeader,
 -			    IN ULONG FromIndex,
 -			    IN PULONG StartingRunIndex)
 -{
 -  UNIMPLEMENTED;
 -  return 0;
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindNextForwardRunClear(IN PRTL_BITMAP BitMapHeader,
 -			   IN ULONG FromIndex,
 -			   IN PULONG StartingRunIndex)
 -{
 -  ULONG ulSize = 0;
 -
 -  if (BitMapHeader && FromIndex < BitMapHeader->SizeOfBitMap &&
StartingRunIndex)
 -    *StartingRunIndex = NTDLL_FindClearRun(BitMapHeader, FromIndex, &ulSize);
 -
 -  return ulSize;
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindFirstRunSet(IN PRTL_BITMAP BitMapHeader,
 -		   IN PULONG StartingIndex)
 -{
 -  ULONG Size;
 -  ULONG Index;
 -  ULONG Count;
 -  PULONG Ptr;
 -  ULONG  Mask;
 -
 -  Size = BitMapHeader->SizeOfBitMap;
 -  if (*StartingIndex > Size)
 -  {
 -    *StartingIndex = MAXULONG;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindSetBits(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG NumberToFind,
 +    IN ULONG HintIndex)
 +{
 +    ULONG CurrentBit, CurrentLength;
 +
 +    /* Check for valid parameters */
 +    if (!BitMapHeader || NumberToFind > BitMapHeader->SizeOfBitMap)
 +    {
 +        return MAXULONG;
 +    }
 +
 +    /* Check for trivial case */
 +    if (NumberToFind == 0)
 +    {
 +        return HintIndex;
 +    }
 +
 +    /* Start with hint index, length is 0 */
 +    CurrentBit = HintIndex;
 +    CurrentLength = 0;
 +
 +    /* Loop until something is found or the end is reached */
 +    while (CurrentBit + NumberToFind <= BitMapHeader->SizeOfBitMap)
 +    {
 +        /* Search for the next set run, by skipping a clear run */
 +        CurrentBit += RtlpGetLengthOfRunClear(BitMapHeader,
 +                                              CurrentBit,
 +                                              MAXULONG);
 +
 +        /* Get length of the set bit run */
 +        CurrentLength = RtlpGetLengthOfRunSet(BitMapHeader,
 +                                              CurrentBit,
 +                                              NumberToFind);
 +
 +        /* Is this long enough? */
 +        if (CurrentLength >= NumberToFind)
 +        {
 +            /* It is */
 +            return CurrentBit;
 +        }
 +
 +        CurrentBit += CurrentLength;
 +    }
 +
 +    /* Nothing found */
 +    return MAXULONG;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindClearBitsAndSet(
 +    PRTL_BITMAP BitMapHeader,
 +    ULONG NumberToFind,
 +    ULONG HintIndex)
 +{
 +    ULONG Position;
 +
 +    /* Try to find clear bits */
 +    Position = RtlFindClearBits(BitMapHeader, NumberToFind, HintIndex);
 +
 +    /* Did we get something? */
 +    if (Position != MAXULONG)
 +    {
 +        /* Yes, set the bits */
 +        RtlSetBits(BitMapHeader, Position, NumberToFind);
 +    }
 +
 +    /* Return what we found */
 +    return Position;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindSetBitsAndClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG NumberToFind,
 +    IN ULONG HintIndex)
 +{
 +    ULONG Position;
 +
 +    /* Try to find set bits */
 +    Position = RtlFindSetBits(BitMapHeader, NumberToFind, HintIndex);
 +
 +    /* Did we get something? */
 +    if (Position != MAXULONG)
 +    {
 +        /* Yes, clear the bits */
 +        RtlClearBits(BitMapHeader, Position, NumberToFind);
 +    }
 +
 +    /* Return what we found */
 +    return Position;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindNextForwardRunClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG FromIndex,
 +    IN PULONG StartingRunIndex)
 +{
 +    ULONG Length;
 +
 +    /* Assume a set run first, count it's length */
 +    Length = RtlpGetLengthOfRunSet(BitMapHeader, FromIndex, MAXULONG);
 +    *StartingRunIndex = FromIndex;
 +
 +    /* Now return the length of the run */
 +    return RtlpGetLengthOfRunClear(BitMapHeader, FromIndex, MAXULONG);
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindNextForwardRunSet(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG FromIndex,
 +    IN PULONG StartingRunIndex)
 +{
 +    ULONG Length;
 +
 +    /* Assume a clear run first, count it's length */
 +    Length = RtlpGetLengthOfRunClear(BitMapHeader, FromIndex, MAXULONG);
 +    *StartingRunIndex = FromIndex;
 +
 +    /* Now return the length of the run */
 +    return RtlpGetLengthOfRunSet(BitMapHeader, FromIndex, MAXULONG);
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindFirstRunClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN PULONG StartingIndex)
 +{
 +    return RtlFindNextForwardRunClear(BitMapHeader, 0, StartingIndex);
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindLastBackwardRunClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN ULONG FromIndex,
 +    IN PULONG StartingRunIndex)
 +{
 +    UNIMPLEMENTED;
     return 0;
 -  }
 -
 -  Index = *StartingIndex;
 -  Ptr = (PULONG)BitMapHeader->Buffer + (Index / 32);
 -  Mask = 1 << (Index & 0x1F);
 -
 -  /* Skip clear bits */
 -  for (; Index < Size && ~*Ptr & Mask; Index++)
 -  {
 -    Mask <<= 1;
 -
 -    if (Mask == 0)
 -    {
 -      Mask = 1;
 -      Ptr++;
 -    }
 -  }
 -
 -  /* Return index of first set bit */
 -  if (Index >= Size)
 -  {
 -    *StartingIndex = MAXULONG;
 -    return 0;
 -  }
 -  else
 -  {
 -    *StartingIndex = Index;
 -  }
 -
 -  /* Count set bits */
 -  for (Count = 0; Index < Size && *Ptr & Mask; Index++)
 -  {
 -    Count++;
 -    Mask <<= 1;
 -
 -    if (Mask == 0)
 -    {
 -      Mask = 1;
 -      Ptr++;
 -    }
 -  }
 -
 -  return Count;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindLongestRunClear(PRTL_BITMAP BitMapHeader,
 -		       PULONG StartingIndex)
 -{
 -  /* GCC complaints that it may be used uninitialized */
 -  RTL_BITMAP_RUN br = { 0, 0 };
 -
 -  if (RtlFindClearRuns(BitMapHeader, &br, 1, TRUE) == 1)
 -  {
 -    if (StartingIndex)
 -      *StartingIndex = br.StartingIndex;
 -    return br.NumberOfBits;
 -  }
 -  return 0;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindLongestRunSet(PRTL_BITMAP BitMapHeader,
 -		     PULONG StartingIndex)
 -{
 -  /* GCC complaints that it may be used uninitialized */
 -  RTL_BITMAP_RUN br = { 0, 0 };
 -
 -  if (NTDLL_FindRuns(BitMapHeader, &br, 1, TRUE, NTDLL_FindSetRun) == 1)
 -  {
 -    if (StartingIndex)
 -      *StartingIndex = br.StartingIndex;
 -    return br.NumberOfBits;
 -  }
 -  return 0;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindSetBits(PRTL_BITMAP BitMapHeader,
 -	       ULONG NumberToFind,
 -	       ULONG HintIndex)
 -{
 -  ULONG ulPos, ulEnd;
 -
 -  if (!BitMapHeader || !NumberToFind || NumberToFind >
BitMapHeader->SizeOfBitMap)
 -    return MAXULONG;
 -
 -  ulEnd = BitMapHeader->SizeOfBitMap;
 -
 -  if (HintIndex + NumberToFind > BitMapHeader->SizeOfBitMap)
 -    HintIndex = 0;
 -
 -  ulPos = HintIndex;
 -
 -  while (ulPos < ulEnd)
 -  {
 -    /* FIXME: This could be made a _lot_ more efficient */
 -    if (RtlAreBitsSet(BitMapHeader, ulPos, NumberToFind))
 -      return ulPos;
 -
 -    /* Start from the beginning if we hit the end and had a hint */
 -    if (ulPos == ulEnd - 1 && HintIndex)
 -    {
 -      ulEnd = HintIndex;
 -      ulPos = HintIndex = 0;
 -    }
 -    else
 -      ulPos++;
 -  }
 -  return MAXULONG;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindSetBitsAndClear(PRTL_BITMAP BitMapHeader,
 -		       ULONG NumberToFind,
 -		       ULONG HintIndex)
 -{
 -  ULONG ulPos;
 -
 -  ulPos = RtlFindSetBits(BitMapHeader, NumberToFind, HintIndex);
 -  if (ulPos != MAXULONG)
 -    RtlClearBits(BitMapHeader, ulPos, NumberToFind);
 -  return ulPos;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlNumberOfSetBits(PRTL_BITMAP BitMapHeader)
 -{
 -  ULONG ulSet = 0;
 -
 -  if (BitMapHeader)
 -  {
 -    LPBYTE lpOut = (BYTE *)BitMapHeader->Buffer;
 -    ULONG Length, ulRemainder;
 -    BYTE bMasked;
 -
 -    Length = BitMapHeader->SizeOfBitMap >> 3;
 -    ulRemainder = BitMapHeader->SizeOfBitMap & 0x7;
 -
 -    while (Length--)
 -    {
 -      ulSet += NTDLL_nibbleBitCount[*lpOut >> 4];
 -      ulSet += NTDLL_nibbleBitCount[*lpOut & 0xf];
 -      lpOut++;
 -    }
 -
 -    if (ulRemainder)
 -    {
 -      bMasked = *lpOut & NTDLL_maskBits[ulRemainder];
 -      ulSet += NTDLL_nibbleBitCount[bMasked >> 4];
 -      ulSet += NTDLL_nibbleBitCount[bMasked & 0xf];
 -    }
 -  }
 -  return ulSet;
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -VOID NTAPI
 -RtlSetAllBits(IN OUT PRTL_BITMAP BitMapHeader)
 -{
 -  memset(BitMapHeader->Buffer, 0xff, ((BitMapHeader->SizeOfBitMap + 31) & ~31)
>> 3);
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -VOID NTAPI
 -RtlSetBit(PRTL_BITMAP BitMapHeader,
 -	  ULONG BitNumber)
 -{
 -  PUCHAR Ptr;
 -
 -  if (BitNumber >= BitMapHeader->SizeOfBitMap)
 -    return;
 -
 -  Ptr = (PUCHAR)BitMapHeader->Buffer + (BitNumber / 8);
 -
 -  *Ptr |= (1 << (BitNumber % 8));
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -VOID NTAPI
 -RtlSetBits(PRTL_BITMAP BitMapHeader,
 -	   ULONG StartingIndex,
 -	   ULONG NumberToSet)
 -{
 -  LPBYTE lpOut;
 -
 -  if (!BitMapHeader || !NumberToSet ||
 -      StartingIndex >= BitMapHeader->SizeOfBitMap ||
 -      NumberToSet > BitMapHeader->SizeOfBitMap - StartingIndex)
 -    return;
 -
 -  /* FIXME: It might be more efficient/cleaner to manipulate four bytes
 -   * at a time. But beware of the pointer arithmetics...
 -   */
 -  lpOut = ((BYTE*)BitMapHeader->Buffer) + (StartingIndex >> 3u);
 -
 -  /* Set bits in first byte, if StartingIndex isn't a byte boundary */
 -  if (StartingIndex & 7)
 -  {
 -    if (NumberToSet > 7)
 -    {
 -      /* Set from start bit to the end of the byte */
 -      *lpOut++ |= 0xff << (StartingIndex & 7);
 -      NumberToSet -= (8 - (StartingIndex & 7));
 -    }
 -    else
 -    {
 -      /* Set from the start bit, possibly into the next byte also */
 -      USHORT initialWord = NTDLL_maskBits[NumberToSet] << (StartingIndex &
7);
 -
 -      *lpOut++ |= (initialWord & 0xff);
 -      *lpOut |= (initialWord >> 8);
 -      return;
 -    }
 -  }
 -
 -  /* Set bits up to complete byte count */
 -  if (NumberToSet >> 3)
 -  {
 -    memset(lpOut, 0xff, NumberToSet >> 3);
 -    lpOut = lpOut + (NumberToSet >> 3);
 -  }
 -
 -  /* Set remaining bits, if any */
 -  if (NumberToSet & 0x7)
 -    *lpOut |= NTDLL_maskBits[NumberToSet & 0x7];
 -}
 -
 -
 -/*
 - * @implemented
 - */
 -BOOLEAN NTAPI
 -RtlTestBit(PRTL_BITMAP BitMapHeader,
 -	   ULONG BitNumber)
 -{
 -  PUCHAR Ptr;
 -
 -  if (BitNumber >= BitMapHeader->SizeOfBitMap)
 -    return FALSE;
 -
 -  Ptr = (PUCHAR)BitMapHeader->Buffer + (BitNumber / 8);
 -
 -  return (BOOLEAN)(*Ptr & (1 << (BitNumber % 8)));
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindFirstRunClear(PRTL_BITMAP BitMapHeader,
 -		     PULONG StartingIndex)
 -{
 -    return RtlFindNextForwardRunClear(BitMapHeader, 0, StartingIndex);
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlNumberOfClearBits(PRTL_BITMAP BitMapHeader)
 -{
 -
 -  if (BitMapHeader)
 -    return BitMapHeader->SizeOfBitMap - RtlNumberOfSetBits(BitMapHeader);
 -  return 0;
 -}
 -
 -/*
 - * @implemented
 - */
 -ULONG NTAPI
 -RtlFindClearBitsAndSet(PRTL_BITMAP BitMapHeader,
 -		       ULONG NumberToFind,
 -		       ULONG HintIndex)
 -{
 -  ULONG ulPos;
 -
 -  ulPos = RtlFindClearBits(BitMapHeader, NumberToFind, HintIndex);
 -  if (ulPos != MAXULONG)
 -    RtlSetBits(BitMapHeader, ulPos, NumberToFind);
 -  return ulPos;
 -}
 -
 -/*
 - * @implemented
 - */
 -CCHAR WINAPI RtlFindMostSignificantBit(ULONGLONG ulLong)
 -{
 -    signed char ret = 32;
 -    DWORD dw;
 -
 -    if (!(dw = (DWORD)(ulLong >> 32)))
 -    {
 -        ret = 0;
 -        dw = (DWORD)ulLong;
 -    }
 -    if (dw & 0xffff0000)
 -    {
 -        dw >>= 16;
 -        ret += 16;
 -    }
 -    if (dw & 0xff00)
 -    {
 -        dw >>= 8;
 -        ret += 8;
 -    }
 -    if (dw & 0xf0)
 -    {
 -        dw >>= 4;
 -        ret += 4;
 -    }
 -    return ret + NTDLL_mostSignificant[dw];
 -}
 -
 -/*
 - * @implemented
 - */
 -CCHAR WINAPI RtlFindLeastSignificantBit(ULONGLONG ulLong)
 -{
 -    signed char ret = 0;
 -    DWORD dw;
 -
 -    if (!(dw = (DWORD)ulLong))
 -    {
 -        ret = 32;
 -        if (!(dw = (DWORD)(ulLong >> 32))) return -1;
 -    }
 -    if (!(dw & 0xffff))
 -    {
 -        dw >>= 16;
 -        ret += 16;
 -    }
 -    if (!(dw & 0xff))
 -    {
 -        dw >>= 8;
 -        ret += 8;
 -    }
 -    if (!(dw & 0x0f))
 -    {
 -        dw >>= 4;
 -        ret += 4;
 -    }
 -    return ret + NTDLL_leastSignificant[dw & 0x0f];
 -}
 -
 -/* EOF */
 +}
 +
 +
 +ULONG
 +NTAPI
 +RtlFindClearRuns(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN PRTL_BITMAP_RUN RunArray,
 +    IN ULONG SizeOfRunArray,
 +    IN BOOLEAN LocateLongestRuns)
 +{
 +    ULONG StartingIndex, NumberOfBits, Run, FromIndex = 0, SmallestRun = 0;
 +
 +    /* Loop the runs */
 +    for (Run = 0; Run < SizeOfRunArray; Run++)
 +    {
 +        /* Look for a run */
 +        NumberOfBits = RtlFindNextForwardRunClear(BitMapHeader, 
 +                                                  FromIndex,
 +                                                  &StartingIndex);
 +
 +        /* Nothing more found? Quit looping. */
 +        if (NumberOfBits == 0) break;
 +
 +        /* Add another run */
 +        RunArray[Run].StartingIndex = StartingIndex;
 +        RunArray[Run].NumberOfBits = NumberOfBits;
 +
 +        /* Update smallest run */
 +        if (NumberOfBits < RunArray[SmallestRun].NumberOfBits)
 +        {
 +            SmallestRun = Run;
 +        }
 +
 +        /* Advance bits */
 +        FromIndex += NumberOfBits;
 +    }
 +
 +    /* Check if we are finished */
 +    if (Run < SizeOfRunArray || !LocateLongestRuns)
 +    {
 +        /* Return the number of found runs */
 +        return Run;
 +    }
 +
 +    while (1)
 +    {
 +        /* Look for a run */
 +        NumberOfBits = RtlFindNextForwardRunClear(BitMapHeader, 
 +                                                  FromIndex,
 +                                                  &StartingIndex);
 +
 +        /* Nothing more found? Quit looping. */
 +        if (NumberOfBits == 0) break;
 +
 +        /* Check if we have something to update */
 +        if (NumberOfBits > RunArray[SmallestRun].NumberOfBits)
 +        {
 +            /* Update smallest run */
 +            RunArray[SmallestRun].StartingIndex = StartingIndex;
 +            RunArray[SmallestRun].NumberOfBits = NumberOfBits;
 +
 +            /* Loop all runs */
 +            for (Run = 0; Run < SizeOfRunArray; Run++)
 +            {
 +                /*Is this the new smallest run? */
 +                if (NumberOfBits < RunArray[SmallestRun].NumberOfBits)
 +                {
 +                    /* Set it as new smallest run */
 +                    SmallestRun = Run;
 +                }
 +            }
 +        }
 +
 +        /* Advance bits */
 +        FromIndex += NumberOfBits;
 +    }
 +
 +    return Run;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindLongestRunClear(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN PULONG StartingIndex)
 +{
 +    ULONG NumberOfBits, Index, MaxNumberOfBits = 0, FromIndex = 0;
 +
 +    while (1)
 +    {
 +        /* Look for a run */
 +        NumberOfBits = RtlFindNextForwardRunClear(BitMapHeader, 
 +                                                  FromIndex,
 +                                                  &Index);
 +
 +        /* Nothing more found? Quit looping. */
 +        if (NumberOfBits == 0) break;
 +
 +        /* Was that the longest run? */
 +        if (NumberOfBits > MaxNumberOfBits)
 +        {
 +            /* Update values */
 +            MaxNumberOfBits = NumberOfBits;
 +            *StartingIndex = Index;
 +        }
 +
 +        /* Advance bits */
 +        FromIndex += NumberOfBits;
 +    }
 +
 +    return MaxNumberOfBits;
 +}
 +
 +ULONG
 +NTAPI
 +RtlFindLongestRunSet(
 +    IN PRTL_BITMAP BitMapHeader,
 +    IN PULONG StartingIndex)
 +{
 +    ULONG NumberOfBits, Index, MaxNumberOfBits = 0, FromIndex = 0;
 +
 +    while (1)
 +    {
 +        /* Look for a run */
 +        NumberOfBits = RtlFindNextForwardRunSet(BitMapHeader, 
 +                                                FromIndex,
 +                                                &Index);
 +
 +        /* Nothing more found? Quit looping. */
 +        if (NumberOfBits == 0) break;
 +
 +        /* Was that the longest run? */
 +        if (NumberOfBits > MaxNumberOfBits)
 +        {
 +            /* Update values */
 +            MaxNumberOfBits = NumberOfBits;
 +            *StartingIndex = Index;
 +        }
 +
 +        /* Advance bits */
 +        FromIndex += NumberOfBits;
 +    }
 +
 +    return MaxNumberOfBits;
 +}
 +

 Modified: trunk/reactos/tools/mkhive/mkhive.h
 URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/tools/mkhive/mkhive.h?rev=…
 ==============================================================================
 --- trunk/reactos/tools/mkhive/mkhive.h [iso-8859-1] (original)
 +++ trunk/reactos/tools/mkhive/mkhive.h [iso-8859-1] Tue Dec  8 02:02:36 2009
 @@ -46,6 +46,10 @@
 #define STATUS_OBJECT_NAME_NOT_FOUND     ((NTSTATUS)0xC0000034)
 #define STATUS_INVALID_PARAMETER_2       ((NTSTATUS)0xC00000F0)
 #define STATUS_BUFFER_OVERFLOW           ((NTSTATUS)0x80000005)
 +
 +unsigned char BitScanForward(ULONG * Index, const unsigned long Mask);
 +unsigned char BitScanReverse(ULONG * const Index, const unsigned long Mask);
 +#define RtlFillMemoryUlong(dst, len, val) memset(dst, val, len)

 NTSTATUS NTAPI
 RtlAnsiStringToUnicodeString(

 Modified: trunk/reactos/tools/mkhive/rtl.c
 URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/tools/mkhive/rtl.c?rev=444…
 ==============================================================================
 --- trunk/reactos/tools/mkhive/rtl.c [iso-8859-1] (original)
 +++ trunk/reactos/tools/mkhive/rtl.c [iso-8859-1] Tue Dec  8 02:02:36 2009
 @@ -185,3 +185,25 @@

    //DbgBreakPoint();
 }
 +
 +unsigned char BitScanForward(ULONG * Index, unsigned long Mask)
 +{
 +    *Index = 0;
 +    while (Mask && ((Mask & 1) == 0))
 +    {
 +        Mask >>= 1;
 +        ++(*Index);
 +    }
 +    return Mask ? 1 : 0;
 +}
 +
 +unsigned char BitScanReverse(ULONG * const Index, unsigned long Mask)
 +{
 +    *Index = 0;
 +    while (Mask && ((Mask & (1 << 31)) == 0))
 +    {
 +        Mask <<= 1;
 +        ++(*Index);
 +    }
 +    return Mask ? 1 : 0;
 +}

Best regards,
Alex Ionescu

Re: [ros-dev] [ros-diffs] [tkreuzer] 44464: [RTL] Rewrite the rtl bitmap implementation. The old one was a little .... suboptimal. The new one should outperform the old one by several orders of magnitude, especially RtlFindClearBits that was literally searching bit by bit.