FreeRTOS Modern C++ Wrappers

freertos-mcpp is a C++ wrapper library that allows developers to use the ubiquitous FreeRTOS kernel while simplifying its use by a new API that closely follows the C++ standard classes.

Features

• No virtual classes, the wrapper classes accurately encapsulate the underlying data structures
• Promotes static allocation, optimizing RAM use and reducing heap fragmentation risks
• Public API closely matches the standard C++ thread support library
• The API selects the threading or interrupt service routine (xFromISR) FreeRTOS API calls by detecting ISR context

Compatibility

• C++11 and above
• ESP-IDF platform supported (simply add it to EXTRA_COMPONENT_DIRS, or submodule it into {project}/components)
• MCUXpresso SDK supported (as a west module, drop-in, see mcux/Kconfig)

Porting

In general the library adheres to the FreeRTOS configuration flags, so there's little integration work needed. Certain features and functionality require specific configurations for FreeRTOSConfig.h, see below:

// required globally
#define configSUPPORT_STATIC_ALLOCATION         1

// optional, to allow termination of threads and automatic resource freeing (see thread documentation)
// NOTE: statically allocated threads are still not allowed to return!
#define configSUPPORT_DYNAMIC_ALLOCATION        1
    extern void vTaskExitHandler(void);
#define configTASK_RETURN_ADDRESS               vTaskExitHandler

// optional, for thread termination signalling, used by thread::join
// configNUM_THREAD_LOCAL_STORAGE_POINTERS must be higher than configTHREAD_EXIT_CONDITION_INDEX
#define configNUM_THREAD_LOCAL_STORAGE_POINTERS 1
#define configTHREAD_EXIT_CONDITION_INDEX       0

In addition to the C++ wrappers, there are helper files located in src/helpers for some common use-cases:

1. tasks_static.c is required as source to support static allocation of kernel objects
2. runtime_stats_timer.c is a zero-cost runtime statistics timer for Cortex Mx architectures
3. malloc_free.c and new_delete_ops.cpp redirect heap allocation to FreeRTOS's heap management