JPH0667898A - Task control system - Google Patents

Abstract

PURPOSE:To attain a controllable program by securing a storage area for task control information inherent in each task in respect to a program solely existing in the storage area. CONSTITUTION:This task control system is constituted of only a program 11 solely existing in the storage area, a common memory 12 to be a storage area common to plural tasks, task memories 13, 19 to be independent storage areas in each task, an execution task memory address 15 included in the common memory to specify a task memory corresponding to each task, task stacks 14, 17 independently existing in each task and automatically allocated at their addresses, and saved task memory addresses 16, 18 included in respective task stacks 14, 17, and when a current task is switched, storing the execution task memory address of the task executed up to the switching time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a task control system,
In particular, the present invention relates to a task control method used for the task control method of a program which exists only in a storage area.

[0002]

2. Description of the Related Art A conventional task control method relates to a storage area controlled only by a program that exists in the storage area at the time of executing a task. There is no task memory that allocates the control information for each task, and is uniquely shared by the task stack and the task stack that is automatically allocated by the program to store temporary program control information when the task is executed. The program has only a common memory that stores program control information common to tasks at the time of execution.

In addition, the storage area is allocated to the task stack at the time of executing the program. For example, in C language, register information is saved when executing a function that uses an internal variable or when calling a function. However, the position of the task stack in the storage area could not be fixed.

[0004]

In the above-mentioned conventional task control system, since the common memory is a storage area common to all tasks, task-specific information must be secured on the task stack. Also, there is a drawback that it becomes difficult to specify the size of the required task stack and the program becomes complicated.

[0005]

A task control system according to the present invention comprises a program which exists only in a storage area, a common memory which stores program control information common to the tasks when the program is executed, and an arbitrary task. A task memory that stores control information for each task by arbitrarily assigning an address by the program when the program is executed, and an execution task memory address that exists in the common memory and that stores the address of the task memory by the program, The address is automatically assigned when the task is started, and the task stack that stores temporary program control information when the task is executed and the execution task memory address of the task that was being executed until the task was switched Exists in the task stack where the above program stores That saving task memory address, and a city.

[0006]

Embodiments of the present invention will now be described with reference to the drawings, using the C language as an example.

FIG. 1 is a memory map of an embodiment of the task control system of the present invention.

This memory map is an example in which two tasks, task A and task B, are controlled.

Reference numeral 11 denotes a program, which exists only in the storage area and is executed by a plurality of tasks.

A common memory 12 is a program 1
Controlled by execution of 1. For example, it includes external variables and static variables in C language.

Reference numerals 13 and 19 denote task memories, which are present by the number of tasks and store task-specific information. In this embodiment, there are tasks A and B.

Numerals 14 and 17 denote task stacks, which are present as many as the number of tasks and are used, for example, for saving internal variables in C language and registers for calling a function when executing the program 11. In this embodiment, there are tasks A and B.

Reference numeral 15 denotes an execution task memory address, which stores the address of the task memory 13 of the task which is present in the common memory 12 and is being executed.

Reference numerals 16 and 18 denote evacuation task memory addresses, which store the addresses of the task memories 13 and 19 existing in the task stacks 14 and 17 and corresponding to each task. In this embodiment, there are tasks A and B.

2 and 3 are flow charts showing an example of the operation in the task control system of this embodiment.

2 and 3 show a procedure in which two tasks, task A and task B, execute the program 11 which is uniquely present in the storage area.

The task control of task A and task B is O
Description will be made assuming that S manages.

First, the task A is started, and the execution of the program 11 is started (process 2001). At this time, the task A used by the program 11 under the control of the task A
The address of the task stack 14 for use is already determined by the OS. This task stack 14 is task A
Unless the process is terminated, the OS manages the task A.

Next, the program 11 is a task memory 13 for task A for reading and writing information specific to task A.
The address of the task memory 13 for task A is stored in the execution task memory address 15 in the common memory 12 so as to be referred to in the subsequent operation under the control of the task A (process 2002).

Next, the process A which is the original process of the program 11 is executed (process 2003).

Normally, when the process A is completed, the task A is suspended in the program 11, but when a certain task is suspended, the OS is generally suspended.
The task switching is performed under the control of 1., and the task in the execution waiting state is executed next. In this embodiment, the task B is executed next, but the task A is left as it is.
When the execution is switched from the task B to the task B, the address of the task memory 13 for the task A, that is, the execution task memory address 15 is overwritten with the address of the task memory 19 for the task B as described above. Therefore, the program 11 sets the address of the task memory 13 for task A stored in the execution task memory address 15 to the task stack 1 for task A before suspending the task A.
4 is stored in the saved task memory address 16 in 4 and the task memory 13 for the task A is stored again when the task A is restarted.
Can be referred to (process 2004).

Subsequently, the program 11 suspends the task A and transfers control to the OS. In this case, execution of task A is not completed (process 2005).

Next, task switching is caused by the task control of the OS, task B is started, and execution of the program 11 is started (process 2008).

Here, the subsequent processing 2008 to processing 20
The movement of the program 11 by 12 is the task A already described.
It is exactly the same as the case of Task B for task B 1
7, the task B save task memory address 18 and the task B task memory 19 are only used.

Next, task switching occurs under the task control of the OS, task A is restarted, and execution of the program 11 is restarted (process 2006).

Here, the task A stored in the process 2004
The address of the task memory 13 for read is read from the save task memory address 16 for task A and stored in the executed task memory address 15 (process 2007).

Subsequent processing of the program 11 is from processing 2003 when the task is started, processing from processing 2003 to processing 2
It is also clear that it can be the same as 005.

As described above, the program 11 which performs processing under the multitasking can arbitrarily allocate the task memories 13 and 19 for storing the control information unique to the task.

[0029]

As described above, according to the task control method of the present invention, it is possible to easily secure an independent information storage area for each task in the control method of a program which exists only in the storage area and is executed sequentially. Further, the above-mentioned program, which has been complicated and difficult to realize in the past, can be easily realized.

[Brief description of drawings]

FIG. 1 is a memory map of an embodiment of a task control system of the present invention.

FIG. 2 is a flowchart showing an example of an operation in the task control system of this embodiment.

[Explanation of symbols]

 11 program 12 common memory 13,19 task memory 14,17 task stack 15 execution task memory address 16,18 save task memory address

Claims (1)

[Claims] 1. A program uniquely present in a storage area, a common memory for storing program control information common to a task when the program is executed, and an address arbitrarily specified by the program when the program is executed by an arbitrary task. A task memory that allocates and stores control information for each task, an execution task memory address that exists in the common memory where the program stores the address of the task memory, and an address that is automatically allocated when the task is activated. Exists in the task stack that stores temporary program control information during task execution, and the program stores the execution task memory address of the task that was being executed when the task was switched. Saved task memory address, and A task control method characterized by and.