OS_JamMessage

C Specification

#include <nitro/os.h>
BOOL OS_JamMessage(
OSMessageQueue*   mq,
OSMessage         msg,
s32               flags );
  

Arguments

mq Pointer to the message queue
msg Transmission message
flags When OS_MESSAGE_BLOCK is set, OS_JamMessage blocks the full queue. When OS_MESSAGE_NOBLOCK is set, OS_JamMessage returns whether or not the queue is full.

Return Values

TRUE is returned when the message is successfully sent. FALSE is returned when the queue is full and OS_MESSAGE_NOBLOCK is specified.

Description

OS_JamMessage() is similar to OS_SendMessage except that it inserts a message at the beginning of the specified message queue. Call this function when transmitting high priority messages.

If OS_MESSAGE_BLOCK is set in flags and the queue is full, the thread that called this function is temporarily stopped. It can be restarted by running a reception thread and removing a message from the queue. Be aware that if there are transmission threads of higher priority, they will execute first and may fill up the queue. In this case, this thread will again temporarily stop until an opening in the message queue is made by the reception thread.

When OS_MESSAGE_NOBLOCK is set in flags, the called thread is returned to immediately. When the queue is not full, TRUE is returned. If the queue is full, FALSE is returned.

See Also

OS_InitMessageQueue, OS_SendMessage, OS_ReceiveMessage

Revision History

12/01/2003 Initial Version