/**
* @brief Receives bytes as many as possible, without blocking the
* calling task.
*
* rt_mbx_receive_wp receives at most @e msg_size of bytes of message
* from the mailbox @e mbx then returns immediately.
*
* @param mbx is a pointer to a user allocated mailbox structure.
*
* @param msg points to a buffer provided by the caller.
*
* @param msg_size corresponds to the size of the message to be received.
*
* @return On success, the number of bytes not received is returned. On
* failure a negative value is returned as described below:
* - @b EINVAL: mbx points to not a valid mailbox.
*/
RTAI_SYSCALL_MODE int _rt_mbx_receive_wp(MBX *mbx, void *msg, int msg_size, int space)
{
unsigned long flags;
RT_TASK *rt_current = RT_CURRENT;
int size = msg_size;
CHK_MBX_MAGIC;
flags = rt_global_save_flags_and_cli();
if (mbx->rcvsem.count > 0 && mbx->avbs) {
mbx->rcvsem.count = 0;
if (mbx->rcvsem.type > 0) {
mbx->rcvsem.owndby = rt_current;
enqueue_resqel(&mbx->rcvsem.resq, rt_current);
}
rt_global_restore_flags(flags);
msg_size = mbxget(mbx, (char **)(&msg), msg_size, space);
mbx_signal(mbx);
rt_sem_signal(&mbx->rcvsem);
} else {
rt_global_restore_flags(flags);
}
if (msg_size < size) {
rt_wakeup_pollers(&mbx->poll_send, 0);
}
return msg_size;
}
/**
* @brief Sends a message overwriting what already in the buffer
* if there is no place for the message.
*
* rt_mbx_ovrwr_send sends the message @e msg of @e msg_size bytes
* to the mailbox @e mbx overwriting what already in the mailbox
* buffer if there is no place for the message. Useful for logging
* purposes. It returns immediately and the caller is never blocked.
*
* @return On success, 0 is returned. On failure a negative value
* is returned as described below:
* - @b EINVAL: @e mbx points to an invalid mailbox.
*/
RTAI_SYSCALL_MODE int _rt_mbx_ovrwr_send(MBX *mbx, void *msg, int msg_size, int space)
{
unsigned long flags;
RT_TASK *rt_current = RT_CURRENT;
CHK_MBX_MAGIC;
flags = rt_global_save_flags_and_cli();
if (mbx->sndsem.count > 0)
{
mbx->sndsem.count = 0;
if (mbx->sndsem.type > 0)
{
mbx->sndsem.owndby = rt_current;
enqueue_resqel(&mbx->sndsem.resq, rt_current);
}
rt_global_restore_flags(flags);
msg_size = mbxovrwrput(mbx, (char **)(&msg), msg_size, space);
mbx_signal(mbx);
rt_sem_signal(&mbx->sndsem);
}
else
{
rt_global_restore_flags(flags);
}
return msg_size;
}
