isr_mbx_check

#include <rtl.h>

OS_RESULT isr_mbx_check (
    OS_ID mailbox );    /* The mailbox to check for free space */

The isr_mbx_check function determines the number of messages that can still be added into the mailbox identified by the function argument. You can avoid losing the message by calling the isr_mbx_check function to check for available space in the mailbox before calling the isr_mbx_send function to send a message.

The isr_mbx_check function is in the RL-RTX library. The prototype is defined in rtl.h.

Note

• You can call the isr_mbx_check function only from the IRQ interrupt service routine. You cannot call it from the FIQ interrupt service routine.
• When sending more than one message from ISR, the mailbox might overflow, because the isr_mbx_send puts the messages in the fifo queue, not directly to the mailbox.

The isr_mbx_check function returns the number of message entries in the mailbox that are free.

isr_mbx_send, os_mbx_declare, os_mbx_init

#include <rtl.h>

os_mbx_declare (mailbox1, 20);

void timer1 (void) __irq {
   ..
  if (isr_mbx_check (&mailbox1) != 0) {
    isr_mbx_send (&mailbox1, msg);
  }
   ..
}

Example for sending more than one message from ISR:

#include <rtl.h>

os_mbx_declare (mailbox1, 20);

void timer1 (void) __irq {
  int i,free;
   ..
  free = isr_mbx_check (&mailbox1);
  for (i = 0; i < 16; i++) {
    if (free > 0) {
      free--;
      isr_mbx_send (&mailbox1, msg);
    }
  }
   ..
}