Queue

The Queue class, provides by the underlining mbed OS, is used for queue pointers to data from producer threads to consumer threads. For more information about Queue, please visit MbedOS.

Assembly

Arduino.h

Summary

Constructors

Queue

template<typename T, uint32_t queue_sz> rtos::Queue< T, queue_sz >::Queue  (  ) 

Parameters

Type	Name	Description
typename	T	Data type of the object in the queue.
uint32_t	pool_sz	Size of the queue.

Methods

put

template<typename T, uint32_t queue_sz> osStatus rtos::Queue<T, queue_sz>::put( T* data, uint32_t millisec = 0, uint8_t prio = 0)  

Put message in a Queue.

Parameters

Type	Name	Description
data	T	message pointer.
uint32_t	millisec	timeout value or 0 in case of no time-out. (default: 0)
uint32_t	prio	priority value or 0 in case of default. (default: 0)

Return value

address of the allocated memory block or NULL in case of no memory available.

free

template<typename T, uint32_t pool_sz> osStatus rtos::MemoryPool< T, pool_sz >::free(T* block) 

Free a memory block.

Parameters

Type	Name	Description
typename	block	address of the allocated memory block to be freed.

Return value

osOK on successful deallocation, osErrorParameter if given memory block id is NULL or invalid, or osErrorResource if given memory block is in an invalid memory pool state.

Sample code

typedef struct {
    float    voltage;   /* AD result of measured voltage */
    float    current;   /* AD result of measured current */
    int counter;        /* A counter value               */
} message_t;

MemoryPool<message_t, 16> mpool;
Queue<message_t, 16> queue;
Thread thread;

void send_thread (void) {
    int i = 0;
    while (true) {
        i++; // fake data update
        message_t *message = mpool.alloc();
        message->voltage = (i * 0.1) * 33; 
        message->current = (i * 0.1) * 11;
        message->counter = i;
        queue.put(message);
        delay(1000);
    }
}

void setup() {
	Serial.begin(115200);
	thread.start(callback(send_thread));
}

void loop() {
    osEvent evt = queue.get();
    if (evt.status == osEventMessage) {
        message_t *message = (message_t*)evt.value.p;          
        Serial.printf("\nVoltage: %.2f V\n\r"   , message->voltage);
        Serial.printf("Current: %.2f A\n\r"     , message->current);
        Serial.printf("Number of cycles: %d\n\r", message->counter);            
        mpool.free(message);
    }
}