// name task, period is milliseconds, function call - return pid
int PROCESS_ATTACH(char *name, uint32_t period, void *function); 

// pid of the task - return successful or not
int PROCESS_DETACH(uint16_t pid);

// return successful or not - contains while(1)
int RUN();

usleep(MIN_TIMESLOT_NS); // 1 millisecond for CPU relax into "scheduler()"

#define LOGGER_LEVEL_TRACE          LOW
#define LOGGER_LEVEL_DEBUG          ...
#define LOGGER_LEVEL_INFO           ...
#define LOGGER_LEVEL_WARNING        ...
#define LOGGER_LEVEL_ERROR          ...
#define LOGGER_LEVEL_FATAL          HIGH

// file name and path, logger level start, stdout enable/disable - return successful or not, [MUST] put on the main() head 
int LOGGER_INIT("test.log", LOGGER_LEVEL_DEBUG, LOGGER_STDOUT_ON);

// using like classic printf - return successful or not
int LOGGER_ERROR("color error\n");
int LOGGER_WARN("color warning\n");
int LOGGER_INFO("color infomation\n");
int LOGGER_DEBUG("color debug\n");

// close file, auto flush is always present for every logger raw - return successful or not
int LOGGER_CLOSE();

// Defines a global circular buffer `buf` of a given type and size. The type
// can be native data types or user-defined data types.
// Usage:
// CIRC_GBUF_DEF(uint8_t, byte_buf, 13);
// CIRC_GBUF_DEF(struct foo, foo_buf, 10);
int CIRC_GBUF_DEF(type, buf, size);

// Resets the circular buffer offsets to zero. Does not clean the newly freed slots. 
int CIRC_GBUF_FLUSH(buf);

// Pushes element pointed to by `elem` at the head of circular buffer `buf`.
// This is read-write method, occupancy count increases by one.
int CIRC_GBUF_PUSH(buf, elem)  _push_refd(elem);

// Copies the element at tail of circular buffer `buf` into location pointed
// by `elem`. This method is read-only, does not later occupancy status. 
int CIRC_GBUF_POP(buf, elem)  _pop_refd(elem);

// Returns the number of free slots in the circular buffer `buf` - return: number of slots available.
int CIRC_GBUF_FS(buf)   __circ_gbuf_free_space(&buf);

// OPTIONS:
// Zero slots in circular buffer after a pop.
int CRICBUF_CLEAN_ON_POP