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Mail

Mail class hierarchy

Mail works like a queue, with the added benefit of providing a memory pool for allocating messages (not only pointers).

Mail class reference

Public Member Functions
 Mail ()
 Create and initialize Mail queue. More...
bool empty () const
 Check if the mail queue is empty. More...
bool full () const
 Check if the mail queue is full. More...
T * alloc (uint32_t millisec=0)
 Allocate a memory block of type T. More...
T * calloc (uint32_t millisec=0)
 Allocate a memory block of type T, and set memory block to zero. More...
osStatus put (T *mptr)
 Put a mail in the queue. More...
osEvent get (uint32_t millisec=osWaitForever)
 Get a mail from the queue. More...
osStatus free (T *mptr)
 Free a memory block from a mail. More...

Mail example

This code uses mail to manage measurement.

#include "mbed.h"

/* Mail */
typedef struct {
  float    voltage; /* AD result of measured voltage */
  float    current; /* AD result of measured current */
  uint32_t counter; /* A counter value               */
} mail_t;

Mail<mail_t, 16> mail_box;
Thread thread;

void send_thread (void) {
    uint32_t i = 0;
    while (true) {
        i++; // fake data update
        mail_t *mail = mail_box.alloc();
        mail->voltage = (i * 0.1) * 33; 
        mail->current = (i * 0.1) * 11;
        mail->counter = i;
        mail_box.put(mail);
        wait(1);
    }
}

int main (void) {
    thread.start(callback(send_thread));
    
    while (true) {
        osEvent evt = mail_box.get();
        if (evt.status == osEventMail) {
            mail_t *mail = (mail_t*)evt.value.p;
            printf("\nVoltage: %.2f V\n\r"   , mail->voltage);
            printf("Current: %.2f A\n\r"     , mail->current);
            printf("Number of cycles: %u\n\r", mail->counter);
            
            mail_box.free(mail);
        }
    }
}

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