if (Length != 0) {

        //
        // If the structure is not properly aligned, then raise a data
        // misalignment exception.
        //

        ASSERT((Alignment == 1) || (Alignment == 2) ||
               (Alignment == 4) || (Alignment == 8) ||
               (Alignment == 16));

        StartAddress = (ULONG_PTR)Address;
        if ((StartAddress & (Alignment - 1)) == 0) {

            //
            // Compute the ending address of the structure and probe for
            // write accessibility.
            //

            EndAddress = StartAddress + Length - 1;
            if ((StartAddress <= EndAddress) &&
             [B]   (EndAddress < MM_USER_PROBE_ADDRESS))[/B] {

                //
                // N.B. Only the contents of the buffer may be probed.
                //      Therefore the starting byte is probed for the
                //      first page, and then the first byte in the page
                //      for each succeeding page.
                //
                // If this is a Wow64 process, then the native page is 4K, which
                // could be smaller than the native page size/
                //

                EndAddress = (EndAddress & ~(PageSize - 1)) + PageSize;
                do {
                    *(volatile CHAR *)StartAddress = *(volatile CHAR *)StartAddress;
                    StartAddress = (StartAddress & ~(PageSize - 1)) + PageSize;
                } while (StartAddress != EndAddress);

                return;

            } else {
                [B]ExRaiseAccessViolation();[/B]
            }

        } else {
            ExRaiseDatatypeMisalignment();
        }
    }