get_mpl

Outline

Acquire variable-sized memory block (waiting forever).

C format

 ER      get_mpl (ID mplid, UINT blksz, VP *p_blk);
Parameter(s)

I/O

Parameter

Description

I

 ID      mplid;
ID number of the variable-sized memory pool.

I

 UINT    blksz;
Memory block size to be acquired (in bytes).

O

 VP      *p_blk;
Start address of the acquired memory block.



Explanation

This service call acquires a variable-size memory block of the size specified by parameter blksz from the variable-size memory pool specified by parameter mplid, and stores its start address into the area specified by parameter p_blk.

If no variable-size memory blocks could be acquired from the target variable-size memory pool (no successive areas equivalent to the requested size were available) when this service call is issued, this service call does not acquire variable-size memory blocks but queues the invoking task to the target variable-size memory pool wait queue and moves it from the RUNNING state to the WAITING state (variable-size memory block acquisition wait state).

The WAITING state for a variable-sized memory block is cancelled in the following cases.

WAITING State for a Variable-sized Memory Block Cancel Operation

Return Value

The variable-size memory block that satisfies the requested size was returned to the target variable-size memory pool as a result of issuing rel_mpl.

E_OK

The task at the top of the transmission wait queue was forcedly released from waiting by following either.

- Forced release from waiting (accept rel_wai while waiting).

- Forced release from waiting (accept irel_wai while waiting).

- Forced release from waiting (accept ter_tsk while waiting).

- The time specified by tmout for tget_mpl has elapsed.

E_OK

Forced release from waiting (accept rel_wai while waiting).

E_RLWAI

Forced release from waiting (accept irel_wai while waiting).

E_RLWAI

The variable-sized memory pool is reset as a result of issuing vrst_mpl.

EV_RST



Note 1 For the size of the memory block, refer to "7.3.2 Size of Variable-sized memory block".

Note 2 Invoking tasks are queued to the target variable-size memory pool wait queue in the FIFO order.

Note 3 The contents of the block are undefined.

Note 4 The alignment number of memory blocks is 1. To enlarge the alignment number to 4, specify unique section to Section name assigned to the memory pool area (mpl_section) in Variable-sized Memory Pool Information (variable_memorypool[]) and locate the section to 4-bytes boundary address when linking.

Return value

Macro

Value

Description

E_OK

0

Normal completion.

E_PAR

-17

Parameter error.

- blksz == 0

- blksz exceeds the maximum size that can be acquired.

E_ID

-18

Invalid ID number.

- mplid < 0

- mplid > VTMAX_MPL

E_CTX

-25

Context error.

- This service call was issued from a non-task.

- This service call was issued in the CPU locked state.

- This service call was issued in the dispatching disabled state.

- This service call was issued in the status "PSW.IPL > kernel interrupt mask level".

E_RLWAI

-49

Forced release from the WAITING state.

- Accept rel_wai/irel_wai while waiting.

EV_RST

-127

Released from WAITING state by the object reset (vrst_mpl)