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Function DLLs#

ATLAS supports function DLLs written in .NET Framework.

Code Structure#

Function classes:

  • Implement MESL.SqlRace.Domain.Functions.DotNet.IDotNetFunction
  • Are decorated with:
    • System.Serializable
    • System.ComponentModel.Composition.ExportAttribute

Example

[Serializable]
[Export(typeof(IDotNetFunction))]
public class VCarMultipliedByThree : IDotNetFunction
{
    public void Initialize(IFunctionManager functionManager)
    {
        // ...
    }

    public void Execute(IExecutionContext executionContext)
    {
        // ...
    }
}

Initialize#

Initalize is called at startup.

Example

var functionDefinition = functionManager .CreateFunctionDefinition(DotNetFunctionConstants.UniqueId);

functionDefinition.CalculateOverWholeSession = false;
functionDefinition.FunctionMode = FunctionMode.Instantaneous;
functionDefinition.InputParameterIdentifiers.Add("vCar:Chassis");
functionDefinition.InterpolateBetweenSamples = true;
functionDefinition.JoinGapsAroundNull = true;
functionDefinition.Name = @"vCarTimesThree";
this.Name = @"vCarTimesThree";

var implementationDefintion = (DotNetFunctionImplementationDefinition)functionDefinition.ImplementationDefinition;
implementationDefintion.Function = this;

functionDefinition.OutputParameterDefinitions.Add(
    new FunctionOutputParameterDefinition
    {
        ApplicationName = "Functions",
        Identifier = "vCarTimesThree",
        Name = "vCarTimesThree",
        BitShift = 0x00,
        ByteOrder = ByteOrderType.BigEndian,
        DataBitMask = 0x00,
        Description = @"Multiply vCar three times",
        FormatOverride = @"%5.1f",
        MaximumValue = 900,
        OffsetValue = 0x00,
        Units = "kph"
    });

functionDefinition.StoreInSession = true;
functionManager.Build(functionDefinition);

Multiple input identifiers and output parameter definitions can be defined.

Execute#

Execute is called with a context providing function input and output arrays, and other configuration.

Example

// find input
int vCarIndex = executionContext.FunctionInput.InputParameterIndexes["vCar:Chassis"];
double[] vCarInputValues = executionContext.FunctionInput.Values[vCarIndex];

// find output
int vCarTripledIndex = functionOutput.OutputParameterIndexes["vCarTripled:FunctionParameters"];
double[] vCarTripledOutputValues = functionOutput.OutputParametersValues[vCarTripledIndex];

// compute
for (var i = 0; i < executionContext.FunctionInput.Timestamps.Length; i++)
{
    vCarTripledOutputValues[i] = vCarInputValues[i] * 3;
}
  • The function execution framework will sample the input data based on each function’s properties.
  • You must provide an output for each input timestamp:
    function input and output arrays will be the same length as FunctionInput.Timestamps.Length.
  • Return double.NaN for timestamps with no value.

Constants#

A function class can access constants through a two-step process:

  1. Specify the identifiers for required constants during Initialize;
  2. Access constant values through the IExecutionContext during Execute.

This enables ATLAS to disable a function if the requirements are not met.

Discovery#

Locate function DLLs in:
%USERPROFILE%\Documents\McLaren Electronic Systems\SQL Race\Functions

ATLAS checks this directory at startup.

When a function DLL is loaded, it is available in the Parameter Browser under Functions.
Function output parameters will also be available to use as inputs to other functions.
In FDL, they can be referenced like: $rSlipRatioFL:FunctionParameters