T-Kernel Specification (1.B0.02)

4.6. MEMORY POOL MANAGEMENT FUNCTIONS 149
mpfatr:= (TA_TFIFO || TA_TPRI) | [TA_NODISWAI]
| (TA_RNG0 || TA_RNG1 || TA_RNG2 || TA_RNG3)
TA TFIFO
TA TPRI
TA RNGn
TA NODISWAI
Tasks waiting for memory allocation are queued in FIFO order
Tasks waiting for memory allocation are queued in priority order
Memory access privilege is set to protection level n
Wait disabling by tk dis wai is prohibited
#define TA_TFIFO 0x00000000 /* manage task queue by FIFO */
#define TA_TPRI 0x00000001 /* manage task queue by priority */
#define TA_NODISWAI 0x00000080 /* reject wait disabling */
#define TA_RNG0 0x00000000 /* protection level 0 */
#define TA_RNG1 0x00000100 /* protection level 1 */
#define TA_RNG2 0x00000200 /* protection level 2 */
#define TA_RNG3 0x00000300 /* protection level 3 */
The queuing order of tasks waiting for memory block allocation from a memory pool can be designated
in TA TFIFO or TA TPRI. If the attribute is TA TFIFO, tasks are ordered by FIFO, whereas TA TPRI
designates queuing of tasks in order of their priority setting.
TA RNGn is designated to limit the protection levels at which memory can be accessed. Only tasks
running at the same or higher protection level than the one designated can access the allocated memory.
If a task running at a lower protection level attempts access, a CPU protection fault exception is raised.
For example, memory allocated from a memory pool designated as TA RNG1 can be accessed by tasks
running at levels TA RNG0 or TA RNG1, but not by tasks running at levels TA RNG2 or TA RNG3.
The created memory pool is in resident memory in system space. There is no T-Kernel function for
creating a memory pool in task space.
[Additional Notes]
In the case of a fixed-size memory pool, separate memory pools must be provided for different block
sizes. That is, if various memory block sizes are required, memory pools must be created for each block
size.
For the sake of portability, the TA RNGn attribute must be accepted even by a system without an MMU.
It is possible, for example, to treat all TA RNGn designations as equivalent to TA RNG0; but error must
not be returned.
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T-Kernel 1.B0.02