T-Kernel Specification (1.B0.02)

4.5. EXTENDED SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 121
tk snd mbf
Send Message to Message Buffer
[C Language Interface]
ER ercd = tk_snd_mbf ( ID mbfid, VP msg, INT msgsz, TMO tmout ) ;
[Parameters]
ID mbfid Message buffer ID
INT msgsz Send message size (in bytes)
VP msg Start address of send message packet
TMO tmout Timeout designation
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E PAR
E DLT
E RLWAI
E DISWAI
E TMOUT
E CTX
Normal completion
Invalid ID number (mbfid is invalid or cannot be used)
Object does not exist (the message buffer designated in mbfid does not exist)
Parameter error (msgsz ≤ 0, msgsz > maxmsz,value that cannot be used in msg, or
tmout ≤ (−2))
The object being waited for was deleted (message buffer was deleted while waiting)
Wait state released (tk rel wai received in wait state)
Wait released by wait disabled state
Polling failed or timeout
Context error (issued from task-independent portion or in dispatch disabled state)
[Description]
Sends the message at the address designated in msg to the message buffer designated in mbfid. The
message size is indicated in msgsz. This system call copies msgsz bytes starting from msg to the message
queue of message buffer mbfid. The message queue is implemented as a ring buffer.
If msgsz is larger than the maxmsz designated with tk cre mbf, error code E PAR is returned.
If there is not enough available buffer space to accommodate message msg in the message queue, the
task issuing this system call goes to send wait state and is queued waiting for buffer space to become
available (send queue). Waiting tasks are queued in either FIFO or priority order, depending on the
designation made with tk cre mbf.
A maximum wait time (timeout) can be set in tmout. If the tmout time elapses before the wait release
condition is met (before there is sufficient buffer space), the system call terminates, returning timeout
error code E TMOUT.
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T-Kernel 1.B0.02