T-Kernel Specification (1.B0.02)

4.4. SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 105
tk ref mbx
Reference Mailbox Status
[C Language Interface]
ER ercd = tk_ref_mbx ( ID mbxid, T_RMBX *pk_rmbx ) ;
[Parameters]
ID mbxid Mailbox ID
T RMBX* pk rmbx Address of packet for returning status information
[Return Parameters]
ER ercd Error code
pk rmbx detail:
VP exinf Extended information
ID wtsk Waiting task information
T MSG* pk msg Start address of next message packet to be received
(Other implementation-dependent parameters may be added beyond this point.)
[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 (the return parameter packet address cannot be used)
[Description]
References the status of the mailbox designated in mbxid, passing in the return parameters the next
message to be received (the first message in the message queue), waiting task information (wtsk), and
extended information (exinf).
wtsk indicates the ID of a task waiting for the mailbox. If there are multiple waiting tasks, the ID of
the first task in the queue is returned. If there are no waiting tasks, wtsk = 0 is returned.
If the designated mailbox does not exist, error code E NOEXS is returned.
pk msg indicates the message that will be received the next time tk rcv mbx is issued. If there are no
messages in the message queue, pk msg = NULL is returned. At least one of pk msg = NULL and
wtsk = 0 is always true for this system call.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02