USBB17RX78K4-XXX NEC Electronics, USBB17RX78K4-XXX Datasheet - Page 27

• Manufacturer Part Number: USBB17RX78K4-XXX
• Description: 78K/4 series realtime OS
• Manufacturer: NEC Electronics

2.5 Memory Management
task acquires memory when necessary, and releases it when unnecessary. By using this feature, it is not necessary
to acquire a memory area in advance for even two or more tasks, so that the memory can be efficiently used.
returned after it has been used and is no longer necessary. If one memory block cannot be acquired, state transition
of a task does not take place, but only an error code is returned. The size of one memory block is fixed to a value
specified on system creation.
model, the first 1 byte with the small model, are used as a queue link area. Therefore, the area that can be used as a
message area is the area excluding link area.
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RX78K/IV performs dynamic memory management based on a memory block of fixed size. This means that a
The memory block of RX78K/IV is dynamically acquired by a system call under execution by the system, and is
Usually, an acquired memory block is used as a message area, in which case the first 2 bytes with the large
Caution When using a memory block as a message area, please make the size of the memory block a
multiple of 2. Operation is not guaranteed if the size is not a multiple of 2.
Memory pool
first address
CHAPTER 2
Fig. 2-4 Memory Pool Configuration
Memory block
Memory block
Memory block
Queue area
Queue area
Queue area
Queue area
Queue area
BASIC FUNCTIONS OF RX78K/IV
=0
(Queue area of last memory block)
Size of 1 memory block
Free block management area
Large model : 4 bytes
Small model : 2 bytes
Large model : 2 bytes
Small model : 1 byte