Our Phoenix Flight Management system features a Fatigue Index score which is calculated by way of a third party proprietary DLL. This fatigue score is an important indicator of crew safety and is essential to our clients. The supplier of this DLL is upgrading it and we will be required to pass values to and from it as INT64 variables.
Is there a corresponding variable type to INT64 in DF19.0 that we can employ, or will we have to build our own DLL in C# to pass data back and forth from our application to the fatigue DLL? (We have done this in the past but would like to encapsulate the fatigue process within Dataflex if possible).

Below is a small scrap of a sample C# program provided by the DLL designers:

if (validData)
Int64[] l_fatigueTime = new Int64[logCount];
Double[] l_fatigueValue = new Double[logCount];
Marshal.Copy(fatigueTime, l_fatigueTime, 0, logCount);
Marshal.Copy(fatigueValue, l_fatigueValue, 0, logCount);

Int32[] l_sleepID = new Int32[sleepCount];
Int64[] l_sleepStart = new Int64[sleepCount];
Int64[] l_sleepFinish = new Int64[sleepCount];
Marshal.Copy(sleepID, l_sleepID, 0, sleepCount);
Marshal.Copy(sleepStart, l_sleepStart, 0, sleepCount);
Marshal.Copy(sleepFinish, l_sleepFinish, 0, sleepCount);

Int64[] l_FAID_fatigueTime = new Int64[FAID_logCount];
Double[] l_FAID_fatigueValue = new Double[FAID_logCount];

I will very much appreciate any assistance anyone can provide.