RtlByteToInt8 - NtDoc

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

//
// BYTE -> INT8 conversion
//
_Must_inspect_result_
__inline
NTSTATUS
RtlByteToInt8(
    _In_ BYTE bOperand,
    _Out_ _Deref_out_range_(==, bOperand) INT8* pi8Result)
{
    NTSTATUS status;
    
    if (bOperand <= INT8_MAX)
    {
        *pi8Result = (INT8)bOperand;
        status = STATUS_SUCCESS;
    }
    else
    {
        *pi8Result = INT8_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }
    
    return status;
}

#endif
#endif
View code on GitHub