T-Kernel Specification (1.B0.02)

4.4. SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 101
tk snd mbx
Send Message to Mailbox
[C Language Interface]
ER ercd = tk_snd_mbx ( ID mbxid, T_MSG *pk_msg ) ;
[Parameters]
ID mbxid Mailbox ID
T MSG* pk msg Message packet address
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E PAR
Normal completion
Invalid ID number (mbxid is invalid or cannot be used)
Object does not exist (the mailbox designated in mbxid does not exist)
Parameter error (pk msg is a value that cannot be used)
[Description]
Sends the message packet having pk msg as its start address to the mailbox designated in mbxid. The
message packet contents are not copied; only the start address (pk msg) is passed at the time of message
receipt.
If tasks are already waiting for messages in the same mailbox, the WAIT state of the task at the head of
the queue is released, and the pk msg passed to tk snd mbx is sent to that task, becoming a parameter
returned by tk rcv mbx. If there are no tasks waiting for messages in the designated mailbox, the sent
message goes in the message queue of that mailbox. In neither case does the task issuing tk snd mbx
enter WAIT state.
pk msg is the start address of the packet containing the message, including header. The message header
has the following format.
typedef struct t_msg {
? ? /* Implementation-dependent contents (fixed size) */
} T_MSG;
typedef struct t_msg_pri {
T_MSG msgque; /* message queue area */
PRI msgpri; /* message priority */
} T_MSG_PRI;
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02