T-Kernel Specification (1.B0.02)

118 CHAPTER 4. T-KERNEL/OS FUNCTIONS
tk cre mbf
Create Message Buffer
[C Language Interface]
ID mbfid = tk_cre_mbf ( T_CMBF *pk_cmbf ) ;
[Parameters]
T CMBF* pk cmbf Information about the message buffer to be created
pk cmbf detail:
VP exinf Extended information
ATR mbfatr Message buffer attributes
INT bufsz Message buffer size (in bytes)
INT maxmsz Maximum message size (in bytes)
(Other implementation-dependent parameters may be added beyond this point.)
[Return Parameters]
ID mbfid Message buffer ID
or Error Code
[Error Codes]
E OK
E NOMEM
E LIMIT
E RSATR
E PAR
Normal completion
Insufficient memory (memory for control block or ring buffer area cannot be allocated)
Number of message buffers exceeds the system limit
Reserved attribute (mbfatr is invalid or cannot be used)
Parameter error (pk cmbf is invalid, or bufsz or maxmsz is negative or invalid)
[Description]
Creates a message buffer, assigning to it a message buffer ID.
This system call allocates a control block to the created message buffer. Based on the information
designated in bufsz, it allocates a ring buffer area for message queue use (for messages waiting to be
received).
A message buffer is an object for managing the sending and receiving of variable-size messages. If differs
from a mailbox (mbx) in that the contents of the variable-size messages are copied when the message is
sent and received. It also has a function for putting the sending task in WAIT state when the buffer is
full.
exinf can be used freely by the user to set miscellaneous information about the created message buffer.
The information set in this parameter can be referenced by tk ref mbf. If a larger area is needed for
indicating user information, or if the information may need to be changed after the message buffer is
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02