T-Kernel Specification (1.B0.02)

4.6. MEMORY POOL MANAGEMENT FUNCTIONS 159
tk get mpl
Get Variable-size Memory Block
[C Language Interface]
ER ercd = tk_get_mpl ( ID mplid, INT blksz, VP *p_blk, TMO tmout ) ;
[Parameters]
ID mplid Variable-size memory pool ID
INT blksz Memory block size (in bytes)
TMO tmout Timeout
[Return Parameters]
ER ercd Error code
VP blk Block start address
[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 (mplid is invalid or cannot be used)
Object does not exist (the variable-size memory pool designated in mplid does not exist)
Parameter error (tmout ≤ (−2))
The object being waited for was deleted (the memory pool 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]
Gets a memory block of size blksz (bytes) from the variable-size memory pool designated in mplid.
The start address of the allocated memory block is returned in blk.
The allocated memory is not cleared to zero, and the memory block contents are indeterminate.
If memory cannot be allocated, the task issuing this system call enters WAIT state.
A maximum wait time (timeout) can be set in tmout. If the tmout time elapses before the wait release
condition is met (memory space does not become available), the system call terminates, returning
timeout error code E TMOUT.
Only positive values can be set in tmout. The time base for tmout (time unit) is the same as that for
system time (= 1 ms).
When TMO POL = 0 is set in tmout, this means 0 was designated as the timeout value, and E TMOUT is
returned without entering WAIT state even if memory cannot be allocated.
When TMO FEVR = (−1) is set in tmout, this means infinity was designated as the timeout value, and
the task continues to wait for memory allocation without timing out.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02