RoundRobinQuantum.hpp

Go to the documentation of this file.

#ifndef INCLUDE_DISTORTOS_INTERNAL_SCHEDULER_ROUNDROBINQUANTUM_HPP_
#define INCLUDE_DISTORTOS_INTERNAL_SCHEDULER_ROUNDROBINQUANTUM_HPP_

#include "distortos/TickClock.hpp"

namespace distortos
{

namespace internal
{

class RoundRobinQuantum
{
public:

    using Representation = uint8_t;

    using Duration = std::chrono::duration<Representation, TickClock::period>;

    constexpr static Duration getInitial()
    {
        return Duration{quantumRawInitializer_};
    }

    constexpr RoundRobinQuantum() :
            quantum_{getInitial()}
    {

    }

    void decrement()
    {
        if (isZero() == false)
            --quantum_;
    }

    Duration get() const
    {
        return quantum_;
    }

    bool isZero() const
    {
        return quantum_ == Duration{0};
    }

    void reset()
    {
        quantum_ = getInitial();
    }

private:

    static_assert(DISTORTOS_TICK_FREQUENCY > 0, "DISTORTOS_TICK_FREQUENCY must be positive and non-zero!");
    static_assert(DISTORTOS_ROUND_ROBIN_FREQUENCY > 0,
            "DISTORTOS_ROUND_ROBIN_FREQUENCY must be positive and non-zero!");

    constexpr static auto quantumRawInitializer_ = (DISTORTOS_TICK_FREQUENCY + DISTORTOS_ROUND_ROBIN_FREQUENCY / 2) /
            DISTORTOS_ROUND_ROBIN_FREQUENCY;

    static_assert(quantumRawInitializer_ > 0 || quantumRawInitializer_ <= UINT8_MAX,
            "DISTORTOS_TICK_FREQUENCY and DISTORTOS_ROUND_ROBIN_FREQUENCY values produce invalid round-robin quantum!");

    Duration quantum_;
};

}   // namespace internal

}   // namespace distortos

#endif  // INCLUDE_DISTORTOS_INTERNAL_SCHEDULER_ROUNDROBINQUANTUM_HPP_