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CHAPTER 2 KERNEL
User’s Manual U14833EJ2V0UM
22
6. Memory management
The memory area is managed by the RX4000 as two types of areas: memory pools and memory blocks. A
memory pool consists of memory blocks grouped together in one large chunk. When memory is necessary to
execute applications such as tasks or handlers, memory blocks can be acquired from a memory pool, and then
returned to the memory pool when no longer required. Performing this kind of dynamic memory manipulation
allows users to make efficient use of a limited memory area.
7.
Time management
The RX4000 manages a software clock to enable specific operations at a fixed interval or at a specified time,
providing functions such as system clock management, task timeout (wait time upper limit setting), and cyclic
handlers.
8.
System status management
System management functions provided in this module include enabling/disabling dispatch (task switching)
and referencing the status of the system. Note that this category appears for the first time in
μ
ITRON4.0; the
majority of its associated service calls are classified into other categories in
μ
ITRON3.0.
9.
Interrupt management
The two kinds of interrupt management functions provided in this module are interrupt control functions for
processing such as enabling/disabling interrupts, and interrupt processing management functions for activating
interrupt service routines corresponding to interrupt sources. Note that because interrupt management is
heavily dependent on the hardware operated by the application, a source file has been provided as a sample,
allowing users to customize these functions.
10. Service call management
This module provides a function that can be used to register functions described by users as service calls.
11. System configuration management
This module provides a function to allow users to register handlers that are used to process exceptions
detected by the CPU, and a function to define the initialization routines called when the system is initialized.
12. Initialization processing
This module is used for processing such as initializing the hardware required for the RX4000 to operate and
initializing the kernel itself. Note that whereas the classifications of the functions in 1 to 11 above are specified
by
μ
ITRON4.0, initialization processing is not subject to this specification.