ULONG
RtlFindSetBitsAndClear(
  IN  PRTL_BITMAP BitMapHeader,
  IN  ULONG NumberToFind,
  IN  ULONG HintIndex
  );

Routine Description:

    This procedure searches the specified bit map for the specified
    contiguous region of set bits, clears the bits and returns the
    number of bits found and the starting bit number which was set then
    clear.

Arguments:

    BitMapHeader - Supplies a pointer to the previously initialized BitMap.

    NumberToFind - Supplies the size of the contiguous region to find.

    HintIndex - Supplies the index (zero based) of where we should start
        the search from within the bitmap.

Return Value:

    ULONG - Receives the starting index (zero based) of the contiguous
        region found.  If such a region cannot be located a -1 (i.e.,
        0xffffffff) is returned.