RtlDWordPtrSub - NtDoc

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// DWORD_PTR subtraction
//
#ifdef _WIN64

#define RtlDWordPtrSub    RtlULongLongSub

#endif
#endif
#endif
View code on GitHub

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// DWORD_PTR subtraction
//
#ifdef _WIN64
// ...
#else

_Must_inspect_result_
__inline
NTSTATUS
RtlDWordPtrSub(
    _In_ DWORD_PTR dwMinuend,
    _In_ DWORD_PTR dwSubtrahend,
    _Out_ _Deref_out_range_(==, dwMinuend - dwSubtrahend) DWORD_PTR* pdwResult)
{
    NTSTATUS status;

    if (dwMinuend >= dwSubtrahend)
    {
        *pdwResult = (dwMinuend - dwSubtrahend);
        status = STATUS_SUCCESS;
    }
    else
    {
        *pdwResult = DWORD_PTR_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }
    
    return status;
} 

#endif
#endif
#endif
View code on GitHub