NtGetCurrentProcessorNumberEx - NtDoc

#ifndef _NTPSAPI_H
//
// Threads
//
#if (PHNT_MODE != PHNT_MODE_KERNEL)
#if (PHNT_VERSION >= PHNT_WIN7)

/**
 * Retrieves the number of the current processor.
 *
 * @param ProcessorNumber An optional pointer to a PROCESSOR_NUMBER structure that receives the processor number.
 * @return ULONG The number of the current processor.
 */
NTSYSCALLAPI
ULONG
NTAPI
NtGetCurrentProcessorNumberEx(
    _Out_opt_ PPROCESSOR_NUMBER ProcessorNumber
    );

#endif
#endif
#endif
View code on GitHub

#ifndef _NTZWAPI_H

NTSYSCALLAPI
ULONG
NTAPI
ZwGetCurrentProcessorNumberEx(
    _Out_opt_ PPROCESSOR_NUMBER ProcessorNumber
    );

#endif
View code on GitHub