lab-rv32i-freertos-mutex/include/freertos/mutex.hpp

#ifndef FREERTOS_CPP_MUTEX_HPP
#define FREERTOS_CPP_MUTEX_HPP

#include <type_traits>

extern "C"
{
#include "FreeRTOS.h"
#include "semphr.h"
#include "task.h"
}

namespace freertos
{

struct StaticMutexStorage final
{
    StaticSemaphore_t control {};
};

class Mutex final
{
public:
    explicit Mutex( StaticMutexStorage & storage ) noexcept
        : handle_ { xSemaphoreCreateMutexStatic( &storage.control ) }
    {
    }

    ~Mutex() noexcept
    {
        if( handle_ != nullptr )
        {
            vSemaphoreDelete( handle_ );
        }
    }

    Mutex( const Mutex & ) = delete;
    Mutex & operator=( const Mutex & ) = delete;
    Mutex( Mutex && ) = delete;
    Mutex & operator=( Mutex && ) = delete;

    [[nodiscard]] bool valid() const noexcept { return handle_ != nullptr; }

    [[nodiscard]] bool lock( TickType_t timeout ) noexcept
    {
        return handle_ != nullptr &&
               xSemaphoreTake( handle_, timeout ) == pdPASS;
    }

    [[nodiscard]] bool unlock() noexcept
    {
        return handle_ != nullptr && xSemaphoreGive( handle_ ) == pdPASS;
    }

    [[nodiscard]] TaskHandle_t owner() const noexcept
    {
        return handle_ == nullptr ? nullptr :
            xSemaphoreGetMutexHolder( handle_ );
    }

    [[nodiscard]] SemaphoreHandle_t native_handle() const noexcept
    {
        return handle_;
    }

private:
    SemaphoreHandle_t handle_ {};
};

template< typename Lockable >
class LockGuard final
{
public:
    explicit LockGuard( Lockable & lockable, TickType_t timeout ) noexcept
        : lockable_ { &lockable }, owns_ { lockable.lock( timeout ) }
    {
    }

    ~LockGuard() noexcept
    {
        if( owns_ )
        {
            ( void ) lockable_->unlock();
        }
    }

    LockGuard( const LockGuard & ) = delete;
    LockGuard & operator=( const LockGuard & ) = delete;
    LockGuard( LockGuard && ) = delete;
    LockGuard & operator=( LockGuard && ) = delete;

    [[nodiscard]] bool owns_lock() const noexcept { return owns_; }

private:
    Lockable * const lockable_;
    const bool owns_;
};

static_assert( !std::is_copy_constructible< Mutex >::value );
static_assert( !std::is_move_constructible< Mutex >::value );
static_assert( !std::is_copy_constructible< LockGuard< Mutex > >::value );
static_assert( !std::is_move_constructible< LockGuard< Mutex > >::value );

} // namespace freertos

#endif