JP2003256219A - Program execution method in incorporated equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a program execution method capable of simultaneously starting a plurality of programs fixedly using a specific memory area in incorporated equipment. <P>SOLUTION: This program execution method in incorporated equipment comprises a step for interrupting a first program which is being executed by the incorporated equipment having a processor 10 and a memory 20, a step for copying the contents of the specific area of the memory 20 used by the first program to another area of the memory 20, and a step for starting a second program using the specific area of the memory 20. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an embedded device (embe
dded device) on the program execution method.

[0002]

2. Description of the Related Art Conventionally, it has been generally practiced to mount a processor for executing software on equipment other than a computer or a computer system represented by a personal computer or a workstation to process information. Such devices are embedded d
evice) is collectively called. In addition, the systems installed in such devices are embedded systems (Embedded syste
m) is called.

Examples of the built-in equipment include AV equipment such as CD player, MD player, DVD player, digital camera, digital television, digital video, next-generation audio equipment, microwave oven, refrigerator, rice cooker, washing machine, etc. White goods, set-top boxes, game consoles,
Home gateway devices such as home servers, mobile phones,
Mobile terminals such as PDAs (personal digital assistants) and car navigation systems can be mentioned.

In recent years, such an embedded device has been evolving as an information home appliance that performs more advanced processing on the premise that a network is used, and the concept of a super distributed system and ubiquitous computing is realized by this. I am trying to do. However, since the processing capability of the processor mounted in the embedded device is severely limited as compared with an ordinary computer from the viewpoint of cost and stability, it is not easy to realize advanced processing in the embedded device.

For example, a processor installed in a normal computer is an MMU (Memory Man) that performs memory management.
age unit) and this and UNIX (R)
OS (Operating Syst) such as Windows and Windows (R)
By combining with em), even a program that uses a specific memory area fixedly, it is possible to start multiple programs at the same time. This is because an MMU-equipped processor and an OS having a paging function can divide a physical memory into blocks called pages or segments for management, and allocate this to a logical address space.

However, embedded devices often use a processor or OS that does not have such a memory management function, and such embedded devices simultaneously activate a plurality of programs that fixedly use a specific memory area. You can't do that, and you must end the running program before starting the next program. For this reason, there is an inconvenience that it is not possible to cope with the sophistication of processing required for the recent embedded devices.

An example of such an inconvenience may be a case where a Java (R) execution environment is built in an embedded system. The software interpreter, which conforms to the code provided by Sun Microsystems and is commonly used in the Java (R) execution environment, uses a large amount of global variables and thus uses a specific area of memory in a fixed manner. For this reason, a plurality of interpreters cannot be activated at the same time in an embedded device that does not have an MMU or paging function, and J
The next Java (R) application could not be started without terminating the Java (R) application.

[0008]

The present invention has been made in view of the above circumstances, and is a program execution method capable of simultaneously activating a plurality of programs that fixedly use a specific memory area in an embedded device. The purpose is to provide.

[0009]

In order to solve the above problems, the present invention provides a step of interrupting a first program which is being executed in an embedded device having a processor and a memory, and which is used by the first program. A step of copying the contents of the specific area of the memory to another area of the memory, and a second step of using the specific area of the memory.
The method for executing a program in an embedded device is provided.

According to this structure, after the execution of the first program is interrupted, the contents of the specific area of the memory used by the first program are copied to another area, and then this specific area is copied. Since the second program that uses the first program is started, the second program that uses the same memory area as the first program can be started without ending the first program that is being executed in the embedded device.

In the present invention, in addition to the above configuration, the step of interrupting the second program, and the contents of a specific area of the memory used by the second program are stored in another memory of the memory. Preferably, the method further comprises the steps of copying to an area, copying the contents of the other area of the memory to the specific area of the memory, and resuming execution of the first program.

As described above, the first program is interrupted, the second program is activated, the second program is interrupted, and the contents of the specific area of the memory used by the second program are changed. The second program without interrupting the second program by copying the contents used by the first program to a specific area of memory and then restarting the execution of the first program. It is possible to restart the execution of the first program, which has been interrupted. After switching the program to be executed in this manner to the first program, it is possible to further switch to the second program.

The first and second programs may be the same program.

Further, when the first and second programs are software interpreters used in the Java (R) execution environment, the Java that has been activated first.
Next Ja without terminating the a (R) application
The va (R) application can be launched.
This enables a plurality of Java (R) applications to be started simultaneously in an embedded device equipped with a Java (R) execution environment using a commonly used software interpreter.

Further, as the processor, a low-end processor which does not have an address conversion function, for example, a processor which does not have an MMU can be preferably used.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram of an embedded system 100 to which a first embodiment of the present invention is applied.
As shown in FIG. 1, the embedded system 100 includes a calculation unit 10, a storage unit 20, a communication unit 30, and an input unit 40.

Such an embedded system 100 can be used, for example, in AV equipment such as CD player, MD player, DVD player, digital camera, digital television, digital video, next-generation audio equipment, microwave oven, refrigerator, etc.
White goods such as rice cookers and washing machines, set-top boxes,
Home gateway devices such as game consoles and home servers,
It is installed in embedded devices such as mobile terminals such as mobile phones, PDAs (personal digital assistants) and car navigation systems.

The calculating means 10 is provided with an ALU (ar (not shown).
CPU (Central Processing) having ithmetic logic unit), CU (control unit), various registers, buses, etc.
A processor such as a Unit) or MPU (micro processor unit).

The storage means 20 is a RAM (random acc
It includes an ess memory 21 and a ROM (read only memory) 22. The RAM 21 is a volatile storage element,
It is used as a variable area, a heap area, or the like when the arithmetic means 10 performs processing. On the other hand, the ROM 22 is a non-volatile storage element, and in the embedded system 100, the Ja 22
va (R) execution environment interpreter 23, Java
The a (R) execution manager 24, a class library, other files for assisting the execution of Java (R), a multi-task OS (Opereting System), and software that performs various functions are stored in the native code of the computing means 10 (class). The code below the library is not shown). Further, the ROM 22 may be a rewritable one such as an EPROM or a flash memory, or may be provided with a memory card or the like which can be attached and detached via a slot.

The interpreter 22 is an arithmetic unit 10.
Has a function of sequentially extracting bytecode instructions from a class file of a predetermined Java (R) application and sequentially executing them. As such an interpreter 22, it is possible to use the one provided by Sun Microsystems, Inc., or the one based on the code, which is adopted in a general Java (R) execution environment. Also, the above J
The ava (R) execution manager 24 is the interpreter 2
2 controls and assists the execution of Java (R) applications. Further, as the multi-task OS in this embodiment, for example, ITRON can be cited. Such a multitasking OS has a function of executing a plurality of tasks in parallel.

The communication unit 30 is a communication interface for connecting to the Internet, and the embedded system 100 can connect to the Internet to send and receive data via the communication unit 30. Further, as the input means 40, for example, a button key, a cursor key or the like is used.

Next, the operation of switching and executing two Java (R) applications in the embedded system 100 configured as described above will be described with reference to FIGS. 2 and 3. FIG. 2 shows J in this embodiment.
FIG. 3 is a flowchart showing the switching operation of the ava (R) application, and FIG. 3 is an explanatory diagram showing the operation of the memory that the embedded system 100 performs on the RAM 21 in accordance with this switching operation, and the memory of the RAM 21 is on the right side of FIG. The area is partially shown, and the processing executed by the embedded system is shown on the left side of FIG.

The feature of the Java (R) application switching operation in this embodiment is that the Java that was previously executed is executed.
a (R) application without terminating the next J
The point is that an ava (R) application can be activated.

A Java (R) application whose source code is created in the Java (R) language is compiled into one or more class files on the vendor side, and
In case of pre-installation, ROM of storage means 20 in advance
22 is stored in the RAM 21 of the storage means 20 by being downloaded by the user after shipment if it is not a printout. Interpreter the bytecode instructions contained in these class files.
By taking out sequentially in 3 and executing sequentially, Ja
The va (R) application is executed. here,
First, referring to FIG. 2A, Java of a WWW browser
(R) Stop the execution of the application and
The case where an ava (R) application is started is shown.

In this switching operation, the interpreter 23 is activated in advance and the Java (R) application of the WWW browser is being executed (hereinafter, the Java of the WWW browser is
Task A to run the va (R) application
Therefore, it is started in response to an input signal from the input means 40 (S101). Here, in the present embodiment, as the interpreter 23, one that complies with the code provided by Sun Microsystems is used.
Global variables frequently used in the interpreter 23 are fixedly stored in the specific area R1 of the RAM 21. Further, the values of local variables (internal variables) of the interpreter 23, the return addresses from the main routine or the subroutine, the contents of the registers of the arithmetic means 10, etc. are managed by the multitasking OS installed in the embedded system 100, and this task It is appropriately stored in the stack A provided corresponding to A. This stack A
The position of is pointed by a TCB (Task Control Block) stored in the task control information management area R3 of the RAM 21, and the OS accesses the stack A through this TCB to input / output a value. .

After starting the switching operation in S101,
The Java (R) application execution manager 24 fetches the bytecode instruction from the class file of the WWW browser and suspends the processing of the interpreter 23 that was being executed (S102), and the contents stored in the specific area R1 of the RAM 21 (interpreter). The value of the global variable used by 23) is copied to the save area R2 of the RAM 21 (S103). The copy destination may be a preset address, or the copy destination may be dynamically determined.

Next, in the task control unit of the OS, the TCB to be used is switched to one that points to a new stack (stack B) (S104), and the interpreter 23 is newly started to execute the Java (R) application of the game. (Hereinafter referred to as task B) is started (S
105). Even in this task B, the interpreter 2
Since 3 fixedly uses the specific area R1 of the RAM 21, the content of the specific area R1 is overwritten by the value of the global variable or the like used in the task B. Further, the values of the local variables and the like of the interpreter 23 used when executing the task B are the TCBs switched in S104.
It is stored in the stack B pointed by. The switching operation ends as described above (S106).

According to the switching operation as described above, in the Java (R) execution environment configured on the embedded system 100 by using the interpreter 23 that fixedly uses the specific area R1, the Java which was previously executed is executed. The next Java (R) application (game) can be started without ending the execution of the (R) application (WWW browser).

After that, when the WWW browser is restarted, the switching operation is restarted by an input signal from the input means 40 or the like as shown in FIG. 2B (S10).
7), the Java (R) application execution manager 24 suspends the processing (task B) of the interpreter 23 that was executing the Java (R) application of the game (S108), and the task A is used in the specific area R1. The global variables and other values are written back from the save area R2 (S109), the TCB used by the task control unit of the OS is returned to the one that points to the stack A (S110), and then the Java (R) of the WWW browser is used.
By restarting the process (task A) of the interpreter 23 that was executing the application (S111),
The switching operation ends (S112).

According to such an operation, the information at the time of interrupting the WWW browser (task A) that was previously executed may be confused with the information used at the time of executing the game (task B) started later. Since it is reproduced without being rewritten, it is possible to correctly restart the WWW browser (task A) from where it was interrupted. Therefore, after the Java (R) application is terminated, the next J
As in the case of activating an ava (R) application, in order to return to the previous Java (R) application, there is no choice but to restart it from the beginning, and the procedure such as repeating the same operation up to the point of interruption is required. Inconvenience can be avoided.

In the above operation, the case where the task A is interrupted, the task B is activated, and then the task B is interrupted and the task A is restarted is shown. However, the same procedure is repeated. It is also possible to continue switching between the task A and the task B by performing the above. In order to continue switching in this way, when suspending one task and restarting the other task, the contents of the specific area R1 used by the suspended task are saved in the save area R2, and The values of global variables used in the task to be restarted may be restored from the save area R2 to the specific area R1.

[Second Embodiment] Next, a second embodiment of the present invention will be described. The embedded system 100 to which this embodiment is applied has a basic configuration that is substantially the same as that of the first embodiment described above, and thus detailed description thereof is omitted. However,
Unlike the first embodiment, the OS installed by the embedded system 100 in the present embodiment is a single task OS.
Is. Even in the single-task OS, the values of local variables and the like are stored in the stack pointed to by the TCB and managed, but the single-task OS does not have a function to switch tasks by properly using a plurality of stacks unlike the multi-task OS. . Therefore, Ja in the present embodiment
The va (R) application execution manager 24 not only saves and restores the information held in the specific area R1, but also saves and restores the contents of the TCB and the stack to effectively manage the task. This point is different from the first embodiment.

Next, with reference to FIGS. 4 and 5, the operation of switching and executing the Java (R) application in this embodiment will be described. FIG. 4 is a flowchart showing the switching operation of the Java (R) application in the present embodiment, and FIG. 5 is an explanatory diagram showing the operation of the memory on the RAM 21 performed by the embedded system 100 in accordance with this switching operation. RAM on the right side of
The memory area 21 is partially shown, and the processing executed by the embedded system is shown on the left side of FIG. Here, W
The case where the execution of the Java (R) application of the WW browser is stopped and the Java (R) application of the game is started is shown.

As shown in FIG. 5 (a), this switching operation is started in response to an input signal from the input means 40 (S201), and the Java (R) application execution manager 24 is executing the WWW browser. The processing of the interpreter 23 (task A) is suspended (S20).
2). Next, the Java (R) application execution manager 24 copies the contents (the values of the global variables used by the interpreter 23) stored in the specific area R1 of the RAM 21 to the save area R2 of the RAM 21 (S203). , TC including the stack used at the time of execution of task A and the information of the stack
The contents of B are saved in the save area R4 (S204). At this time, although depending on the configuration of the arithmetic means 10, the contents of the registers and the like provided in the arithmetic means 10 may be saved as necessary.

Next, the interpreter 23 is newly activated to start the execution of the Java (R) application of the game (hereinafter referred to as task B) (S205), thereby ending the switching operation of the Java (R) application. . In the task B, the values of the global variables and the like used in the task B are held in the specific area R1, and the local variables and the like used in the task B are stored in the stack pointed to by the new TCB.

According to the switching operation as described above, in the Java (R) execution environment configured on the embedded system 100 in which the single task OS is mounted using the interpreter 23 that fixedly uses the specific area R1, In the same manner as the first embodiment, the Java (R) application (game) that has been executed previously is not terminated without ending the execution of the Java (R) application (WWW browser).
Can be started.

After that, when the WWW browser is further restarted, as shown in FIG. 5B, the switching operation is restarted by an input signal from the input means 40 (S20).
7), the Java (R) application execution manager 24 suspends the processing (task B) of the interpreter 23 which was executing the Java (R) application of the game (S208), and the task A is used in the specific area R1. The values of global variables and the like are written back from the save area R2 (S209), and the contents of the TCB and the stack held in the save area R4 at the time of task A interruption are written back to the positions at the time of task A interruption (S210).
Further, when the contents of the registers and the like provided in the arithmetic means 10 are saved, the contents are restored in S210. Next, Java of WWW browser
(R) By restarting the process (task A) of the interpreter 23 that was executing the application (S21
1), the switching operation ends (S212).

According to such an operation, even in the embedded system 100 in which an OS that does not support multitask is installed, as in the first embodiment in which the multitask OS is installed, the WWW browser (task A) can be restarted correctly.

The present invention is not limited to the above-described embodiment, but various modifications can be made. For example, in each of the above-described embodiments, the Java (R) application manager 2 is used.
Although the contents of the specific region R1 are saved and restored by means of 4, it is also possible to save and restore them by another program module. In addition, in the second embodiment,
The Java (R) application manager 24 further saves and restores the TCB and the stack pointed to by the TCB, but this can also be performed by another program module. Furthermore, implementation of the OS is not essential in the present invention. Furthermore, a part of the function of the interpreter 23 may be hardware-configured on the arithmetic unit 10. Furthermore, in each of the above embodiments, a plurality of software interpreters for executing Java (R) applications are activated, but a plurality of other programs may be activated, for example, Java (R).
It may be a software interpreter for executing a language other than. In addition, substitution and modification by technical means usually used by those skilled in the art are possible without departing from the essence of the present invention.

[0040]

As described above, according to the present invention,
After interrupting the execution of the first program, copy the contents of the specific area of the memory used by the first program to another area, and then start the second program that uses this specific area. , 1st running on embedded device
The second program that uses the same memory area can be started without terminating the above program, and thus the first and second programs that use the same memory area in the embedded device can be started at the same time. .

[Brief description of drawings]

FIG. 1 is an embedded system 10 according to an embodiment of the present invention.
It is a block diagram which shows the whole 0 structure.

FIG. 2 is a flowchart showing a switching operation of Java (R) application according to the first embodiment.

FIG. 3 is a diagram showing a process executed by the embedded system 100 and a memory operation in the switching operation shown in FIG. 2 in association with each other.

FIG. 4 is a flowchart showing a switching operation of a Java (R) application according to the second embodiment.

5 is a diagram showing a process executed by the embedded system 100 in the switching operation shown in FIG. 4 and a memory operation in association with each other.

[Explanation of symbols]

10 computing means 20 storage means 21 RAM 22 ROM 23 Interpreter 24 Java (R) Application Execution Manager 30 Communication means 40 Input means

Claims (5)

[Claims] 1. A step of interrupting a first program being executed by an embedded device having a processor and a memory, and contents of a specific area of the memory used by the first program, And a step of activating a second program that uses the specific area of the memory, the program executing method in an embedded device. 2. A step of interrupting the second program; a step of copying the contents of a specific area of the memory used by the second program to another area of the memory; The embedded device according to claim 1, further comprising: a step of copying the content of the another area of the memory into the specific area of the memory; and a step of restarting the execution of the first program. Program execution method in. 3. The program execution method in an embedded device according to claim 1, wherein the first and second programs are the same program. 4. The embedded device according to claim 1, wherein the first and second programs are interpreters that sequentially interpret and execute intermediate code. Program execution method in device. 5. The program execution method in an embedded device, wherein the processor does not have an address conversion function.