IN  SIZE_T SizeOfRange,
  IN  ULONG_PTR Alignment,
  IN  ULONG QuickCheck

Routine Description:

    The function examines the virtual address descriptors to locate
    an unused range of the specified size and returns the starting
    address of the range.


    SizeOfRange - Supplies the size in bytes of the range to locate.

    Alignment - Supplies the alignment for the address.  Must be
                 a power of 2 and greater than the page_size.

    QuickCheck - Supplies a zero if a quick check for free memory
                 after the VadFreeHint exists, non-zero if checking
                 should start at the lowest address.

Return Value:

    Returns the starting address of a suitable range.