Hands-On: C++ Adaptive Application Module

#include "ara/core/result.h"
#include "ara/core/optional.h"
#include 
#include 

// Pure abstract interface: allows mocking in unit tests
class IAdcDriver {
public:
    virtual ~IAdcDriver() = default;
    virtual ara::core::Result Read(uint8_t channel) const noexcept = 0;
};

class TemperatureSensor {
public:
    // Dependency injection: inject ADC driver (real or mock)
    explicit TemperatureSensor(const IAdcDriver &adc, uint8_t channel) noexcept
        : m_adc(adc), m_channel(channel) {}

    // Returns celsius in Q4.12 fixed-point, or error
    ara::core::Result ReadTemperatureCelsius() const noexcept
    {
        auto raw_result = m_adc.Read(m_channel);
        if (!raw_result.HasValue()) {
            return ara::core::Result::FromError(raw_result.Error());
        }

        // Convert ADC raw to millivolts: raw * 3300 / 4095
        const uint32_t mv = (static_cast(raw_result.Value()) * 3300u) / 4095u;

        // LM35 transfer function: 10 mV/°C, offset 0°C at 0V
        // Celsius = mV / 10 — Q4.12: multiply by 4096/10 = 409.6 ≈ use *4096 / 10
        const int16_t celsius_q412 = static_cast((mv * 4096u) / 10000u);

        // Range check: -40°C to +150°C in Q4.12
        constexpr int16_t TEMP_MIN_Q412 = static_cast(-40 * 4096 / 10);
        constexpr int16_t TEMP_MAX_Q412 = static_cast(150 * 4096 / 10);
        if (celsius_q412 < TEMP_MIN_Q412 || celsius_q412 > TEMP_MAX_Q412) {
            return ara::core::Result::FromError(kSensorOutOfRange);
        }
        return celsius_q412;
    }

private:
    const IAdcDriver &m_adc;
    uint8_t m_channel;
};