Binding of VSS to Android Properties

There is a need to store the mapping between the VSS and Android properties. The following needs to be considered:

• Map between VSS leaf to Android Property ID
• Map between VSS leaf to Android Area
• Datatype conversion (e.g. int8 to float)
• Translation

As an example, it might look like

- Vehicle.Powertrain.FuelSystem.Level
	aospId: VehicleProperty::FUEL_LEVEL
	aospArea: VehicleArea::Global
	translation: 
	 	-complex: „$INFO_FUEL_CAPACITY * _VAL_ / 100”

where complex translation is described with another language considered in different ticket

NOTE: The first analysis of translation and description of linear-equation translation is in AASIG-122 - Getting issue details... STATUS

How to describe the complex translations

There is a need to store how to translate the signal from VSS to Android Property. The idea is to have some meta language that can use the references to the other signals and mathematical equations

As an example

- Vehicle.Powertrain.FuelSystem.Level
	translation: 
	 	-complex: „$INFO_FUEL_CAPACITY * _VAL_ / 100”

By the above it means that: To translate the Vehicle.Powertrain.FuelSystem.Level into VehicleProperty::FUEL_LEVEL the result value is = VehicleProperty::INFO_FUEL_CAPACITY * / 100.

It means that this should be generated to something like:

conversionMap["Vehicle.Powertrain.FuelSystem.Level"] = std::bind(convertFuelLevel,
            std::placeholders::_1, VehicleProperty::FUEL_LEVEL, toInt(VehicleArea::GLOBAL));

// ...

static VehiclePropValue convertFuelLevel(std::string value, VehicleProperty id, int32_t area) {
    VehiclePropValue prop = initializeProp(id, area);
    uint8_t valInt = std::stof(value);
    float mililiters = GET_PROP(VehicleProperty::INFO_FUEL_CAPACITY) * valInt / 100;
    prop.value.floatValues = std::vector<float> { mililiters };
    return prop;
}

Enumeration binding

There is a need to provide a way to bind enumerations, whether by meta language (see ticket [How to describe the complex translations] ).

In Android: Subscribe for TIRE_PRESSURE for left-front wheel. In VSS is more flexible (the entities of TIRES can be more than 4)

Instances to VehicleArea binding

For the AOSP Props that have multiple instances, another level of binding needs to be introduced.

Generation of the map and translation functions

By idea the VHAL implementation is using the map between the VSS and Android Properties to translation:

VehiclePropValue aospValue = conversionMap[vssId](vssValue);

Conversion map fragment:

 conversionMap["Vehicle.Powertrain.FuelSystem.Level"] = std::bind(convertFuelLevel,
            std::placeholders::_1, VehicleProperty::FUEL_LEVEL, toInt(VehicleArea::GLOBAL));

The map can be included as a header file during compilation from the deployment files described in other ticket.

Inverse translation (form Android Properties to VSS)

There is a need for inverse to use "setProperty" from Android partition