RtlLongPtrToUChar - NtDoc

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)

//
// LONG_PTR -> UCHAR conversion
//
_Must_inspect_result_
__inline
NTSTATUS
RtlLongPtrToUChar(
    _In_ LONG_PTR lOperand,
    _Out_ _Deref_out_range_(==, lOperand) UCHAR* pch)
{
    NTSTATUS status;
    
    if ((lOperand >= 0) && (lOperand <= 255))
    {
        *pch = (UCHAR)lOperand;
        status = STATUS_SUCCESS;
    }
    else
    {
        *pch = '\0';
        status = STATUS_INTEGER_OVERFLOW;
    }
    
    return status;
}

#endif
#endif
View code on GitHub