OS_JamMessage

Syntax

#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 sending 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. This thread immediately restarts when a receiving thread operates to remove messages from the queue. Be aware that if there are any other sending threads with a higher priority, those will operate first and the queue may fill up again. In such a case, this thread will be suspended again until the receiving thread makes an opening in the message queue.

When OS_MESSAGE_NOBLOCK is set in flags, the calling 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

2003/12/01 Initial version.

CONFIDENTIAL