#ifndef _NTRTL_H
NTSYSAPI
VOID
NTAPI
RtlSetBits(
_In_ PRTL_BITMAP BitMapHeader,
_In_range_(0, BitMapHeader->SizeOfBitMap - NumberToSet) ULONG StartingIndex,
_In_range_(0, BitMapHeader->SizeOfBitMap - StartingIndex) ULONG NumberToSet
);
View code on GitHub
This function is documented in Windows Driver Kit.