T-Kernel Specification (1.B0.02)

4.4. SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 79
tk cre sem
Create Semaphore
[C Language Interface]
ID semid = tk_cre_sem ( T_CSEM *pk_csem ) ;
[Parameters]
T CSEM* pk csem Information about the semaphore to be created
pk csem detail:
VP exinf Extended information
ATR sematr Semaphore attributes
INT isemcnt Initial semaphore count
INT maxsem Maximum semaphore count
(Other implementation-dependent parameters may be added beyond this point.)
[Return Parameters]
ID semid Semaphore ID
or Error Code
[Error Codes]
E OK
E NOMEM
E LIMIT
E RSATR
E PAR
Normal completion
Insufficient memory (memory for control block cannot be allocated)
Semaphore count exceeds the system limit
Reserved attribute (sematr is invalid or cannot be used)
Parameter error (pk csem is invalid; isemcnt or maxsem is negative or invalid)
[Description]
Creates a semaphore, assigning to it a semaphore ID.
This system call allocates a control block to the created semaphore, setting the initial count to isemcnt
and maximum count (upper limit) to maxsem. It must be possible to set maxsem to at least 65535.
Whether values above 65536 can be set is implementation-dependent.
exinf can be used freely by the user to set miscellaneous information about the created semaphore.
The information set in this parameter can be referenced by tk ref sem. If a larger area is needed for
indicating user information, or if the information may need to be changed after the semaphore is created,
this can be done by allocating separate memory for this purpose and putting the memory packet address
in exinf. The OS pays no attention to the contents of exinf.
sematr indicates system attributes in its low bits and implementation-dependent information in the
high bits. Designation in the system attributes part of sematr is as follows.
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T-Kernel 1.B0.02