#ifndef _NTEXAPI_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)

//
// Global atoms
//

/**
 * The NtAddAtom routine adds a Unicode string to the system atom table and
 * returns the corresponding atom identifier.
 *
 * \param AtomName A pointer to a Unicode string containing the atom name.
 * \param Length The length, in bytes, of the string pointed to by AtomName.
 * \param Atom An optional pointer that receives the resulting atom identifier.
 * \return NTSTATUS Successful or errant status.
 * \remarks If the atom already exists, its reference count is incremented and
 * the existing atom identifier is returned.
 * \see https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-addatomw
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtAddAtom(
    _In_reads_bytes_opt_(Length) PCWSTR AtomName,
    _In_ ULONG Length,
    _Out_opt_ PRTL_ATOM Atom
    );

#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwAddAtom(
    _In_reads_bytes_opt_(Length) PCWSTR AtomName,
    _In_ ULONG Length,
    _Out_opt_ PRTL_ATOM Atom
    );

#endif
View code on GitHub