JP3168921B2 - Information processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to multi-task processing to perform an information processing equipment.

[0002]

2. Description of the Related Art Information processing devices capable of executing multitask processing are not limited to personal computers and workstations, but are multifunctional peripheral devices having a plurality of functions as computer peripheral devices such as a printer function and a scanner function. Widely used for control devices.

In such an information processing apparatus, in order to realize a multitasking process, a task switching process is generally performed by executing a task switching process by a timer interrupt at predetermined time intervals.

[0004]

However, when the task switching process is executed by a timer interruption, the task switching process is nested, so that the task switching process is executed twice or more continuously, and the task switching process is performed. Were not done in the prescribed order.

For example, assuming that a scanner task and a printer task are alternately switched at predetermined time intervals by a timer interrupt and operate, a higher-order interrupt than the timer interrupt is performed during execution of the task switching process. Occurs,
The task switching process is interrupted, and the higher-order interrupt is processed. Then, after the upper-level interrupt is processed, the rest of the interrupted task switching process is executed. At this time, if a timer interrupt for task switching occurs, the task switching process nests. As a result, the task switching process is performed twice consecutively. That is, when the task switching process interrupted by the higher-order interrupt should switch from the scanner task to the printer task, after the higher-order interrupt is processed, first, the task switching process by a new timer interrupt is executed. Then, the task is switched from the scanner task to the printer task, and thereafter, the rest of the task switching process interrupted by the higher-order interrupt is resumed, and the task is switched from the printer task to the scanner task. As a result, the task that should have been switched from the scanner task to the printer task returns to the scanner task due to a higher-order interrupt, and the execution of the printer task becomes one.
Will be skipped twice.

The present invention, which has been proposed in view of the above, and its object is to provide an information processing equipment which can prevent malfunction of the task switch due to nesting of task switching processing.

[0007]

In order to achieve the above object, an information processing apparatus according to the present invention is an information processing apparatus capable of executing a multitask process, wherein a timer interrupt is generated. Task switching means for performing task switching processing, counter means for adding a certain number before the task switching processing is started by the task switching means, and subtracting a certain number after the task switching processing ends, and starting the task switching processing A task switching prohibiting means for prohibiting task switching in the task switching process if the content of the counter means is at least a predetermined value.

According to this information processing apparatus, a certain number is added before the task switching process is started by the task switching means,
Counter means for decrementing a certain number after the task switching processing is completed, and task switching inhibiting means for inhibiting task switching in the task switching processing if the content of the counter means is equal to or more than a predetermined value at the start of the task switching processing. Since the nesting is provided, the occurrence of nesting can be detected based on the content of the counter means, and when nesting occurs, task switching is prohibited until the nesting is eliminated. Therefore, malfunction of task switching due to nesting in the task switching process can be prevented. .

The information processing apparatus includes a control device for a multi-function peripheral device having a plurality of functions as a computer peripheral device such as a scanner function and a copy function, a control device for a multi-function office electronic device, and a multi-function home. For example, a control device of an electronic device for use may be considered, but not limited thereto, and a computer itself such as a personal computer or a workstation is also included.

The fixed number to be added or subtracted by the counter means is usually one, but need not always be one.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing a state in which a multifunctional peripheral device having an information processing apparatus according to the present invention is connected to a personal computer. The personal computer 1 employs a GUI using a so-called multi-window, and can simultaneously activate a plurality of application software. The multifunctional peripheral device (hereinafter, referred to as “MFD”) 2 has a plurality of functions such as a facsimile, a printer, an image scanner, and a copier. Note that MFD is an abbreviation for multi-function device.

The personal computer 1 includes a processor 1
1, EEPROM 12, RAM 13, gate array 1
4, interface 15, hard disk drive 17,
A flexible disk drive 18, a display unit 19, an operation unit 20, and a LAN adapter 21 are provided. The processor 11, the EEPROM 12, the RAM 13, the gate array 14, and the interface 15 are interconnected by a bus line. The bus lines include a data bus, an address bus, and a control signal line. Hard disk drive 17, flexible disk drive 18, display unit 1
The operation unit 9, the operation unit 20, and the LAN adapter 21 are connected to the gate array 14.

The processor 11 includes a hard disk drive 17
It operates based on programs such as an OS and various application software installed in the PC and performs information processing. The EEPROM 12 stores various registration data and the like. The RAM 13 is used by various application software and stores various data. The gate array 14 functions as an interface between the processor 11 and the hard disk device 17, flexible disk drive 18, display unit 19, operation unit 20, and LAN adapter 21. The interface 15 controls transmission and reception of data between the personal computer 1 and the MFD 2 based on, for example, standards such as Centronics. Hard disk drive 1
Reference numeral 7 stores various application software programs and the like. Flexible disk drive 18
Reads the contents of a flexible disk and writes data to the flexible disk. The display unit 19
For example, it is composed of an LCD or the like, and displays characters and figures under the control of the processor 11. The operation unit 20 includes, for example, a keyboard or a mouse, and outputs an operation signal based on an operation by a user. The LAN adapter 21 functions as an interface between the personal computer 1 and the LAN.

The MFD 2 includes a CPU 31, a ROM 32, an R
An AM 33, an EEPROM 34, a gate array 35, an interface 36, a scanner 38, a printer 39, a modem 40, an operation unit 41, and a display unit 42 are provided.
CPU31, ROM32, RAM33, EEPROM3
4. Gate array 35 and interface 36
Are interconnected by a bus line. The bus lines include a data bus, an address bus, and a control signal line. A scanner 38, a printer 39, a modem 40, an operation unit 41, and a display unit 42 are connected to the gate array 35. The interface 36 is connected to the interface 15 of the personal computer 1 via a cable 51. A LAN 53 is connected to the LAN adapter 21 of the personal computer 1, and a telephone line 54 is connected to the modem 40 of the MFD 2.

The CPU 31 controls the entire MFD 2.
The ROM 32 stores a program for controlling the MFD 2 and the like. The RAM 33 stores various data. The EEPROM 34 stores various flags, registration data, and the like. The gate array 35 includes a CPU 31, a scanner 38, a printer 39, a modem 40, an operation unit 41,
And an interface with the display unit 42. The interface 36 controls transmission and reception of data between the personal computer 1 and the MFD 2 based on a standard such as Centronics. The scanner 38 reads an image of a document and converts it into an image signal.
The printer 39 prints an image based on the image data. When transmitting and receiving facsimile communication, the modem 40 modulates a carrier with transmission data and demodulates a received carrier to extract received data. The operation unit 41 includes a group of key switches and the like, and outputs an operation signal according to an operation by a user. The display unit 42 includes an LCD or the like, and performs various displays under the control of the CPU 31.

The hard disk device 17 of the personal computer 1 allows the personal computer 1 to perform facsimile communication between the personal computer 1 and another facsimile device using the modem 40 of the MFD 2 or creates the personal computer 1 using the printer 39. The personal computer 1 captures an image signal read out using the scanner 38 or prints out a scanned document or image.
MFD control application software for realizing various functions is installed. This MFD
The control application software inserts the flexible disk into the flexible disk drive 18 and performs a predetermined operation, so that the hard disk drive 17
Installed in The MFD control application software includes software called a FAX driver for performing data conversion such as conversion of text data to bitmap data, software called a log manager for managing and displaying a communication history, and communication between the personal computer 1 and the MFD 2. It is composed of software called a status monitor for managing the transmission and reception of the data.

That is, the CPU 31 of the MFD 2 generates a timer interrupt and performs a task switching process, and a certain number is added before the task switching process is started by the task switching device. Counter means for decrementing a certain number after completion and task switching prohibiting means for prohibiting task switching in task switching processing when the content of the counter means is equal to or more than a predetermined value at the start of task switching processing.

The ROM 32 of the MFD 2 has a task switching program for generating a timer interrupt and performing task switching processing, and a certain number added before the task switching processing by the task switching program is started. A program storing a program including a task switching prohibition program for prohibiting task switching in the task switching process if the content of the counter means for decrementing a certain number after completion is equal to or more than a predetermined value at the start of the task switching process. Make up the medium.

Next, the essential points of the operation of the MFD 2 configured as described above will be described. The MFD 2 causes a scanner 38 to read an original, converts the image signal into image data and outputs the image data to the personal computer 1, and prints an image on a printer 39 based on print data input from the personal computer 1. A printer function for causing the printer 39 to print an image read by the scanner 38; a document function for causing the scanner 38 to read an original; converting the image signal into facsimile data and sending it to the telephone line 54; A facsimile function for causing the printer 39 to print facsimile data input via the telephone 54, transmitting facsimile data input from the personal computer 1 to the telephone line 54, and transmitting facsimile data input via the telephone line 54 to the personal computer 1. Compilation Over data 1
And a PC facsimile function for outputting to a PC.

The CPU 31 of the MFD 2 has a scanner task for realizing the scanner function, a printer task for realizing the printer function, a copy task for realizing the copy function, and a facsimile function. A facsimile task and a PC facsimile task for realizing a PC facsimile function are executed. Further, when simultaneously operating a plurality of these functions, a plurality of tasks for realizing the functions are switched at predetermined time intervals by a timer interrupt to execute a multitask process.

By the way, if a higher-order interrupt occurs while the task switching process is being executed by a timer interrupt, the task switching process is interrupted and the higher-order interrupt is processed.
Then, after the upper-level interrupt is processed, the rest of the interrupted task switching process is executed. At this time, if a timer interrupt for task switching occurs, the task switching process nests. If no action is taken, the task switching process is performed twice consecutively. For example, if the task switching process interrupted by a higher-order interrupt should have switched from a scanner task to a printer task, after the higher-order interrupt has been processed,
First, a task switching process by a new timer interrupt is executed and the task is switched from the scanner task to the printer task. After that, the rest of the task switching process interrupted by the higher-order interrupt is resumed and the task is switched from the printer task to the scanner task. I will. As a result, the task that should have been switched from the scanner task to the printer task returns to the scanner task due to a higher-order interrupt, and the execution of the printer task is skipped once.

In order to solve such a problem caused by the nesting of the task switching process, a counter is provided which is incremented before the task switching process is started and decremented after the task switching process is completed. If the content of is more than one, the task switching in the task switching process is prohibited.
The counter is realized by using the RAM 33 of the MFD 2.

Assuming that the content of the counter is 0, the counter is incremented before the task switching processing is started by the timer interruption. Is 1
It is. Here, if a higher-level interrupt occurs during the execution of the task switching process and the task switching process is interrupted, the task switching process does not end, so that the content of the counter is maintained at 1. When the higher-order interrupt is processed, the rest of the interrupted task switching process is executed. At this time, when a timer interrupt for performing the task switching process occurs, the task The switching process is performed. Therefore, the content of the counter is 2 at the start of the task switching process. Thus, the content of the counter is 2
In this case, the task switching process ends without switching the task. The task was not switched,
Since the task switching process has been completed, the content of the counter becomes 1 at this point. Then, the rest of the task switching process interrupted by the higher-order interrupt is restarted, the task switching is actually performed, and after the termination, the content of the counter is decremented to zero.

As described above, when the task switching processing is nested, the content of the counter becomes a value of 2 or more according to the number of layers of the nested structure. In this case, the task switching processing is terminated without switching the task. Therefore, the task is not switched until the nesting is eliminated. Therefore, erroneous task switching due to nesting of task switching processing can be prevented.

Next, the procedure of the task switching control process including the task switching process and the task switching prohibition process will be described.
This will be described with reference to the flowchart shown in FIG.

When an interrupt for task switching occurs, M
The CPU 31 of the FD 2 increments the counter (S1), and determines whether the counter value is 2 or more (S2).

If the counter value is not 2 or more (S2: N
O), the CPU 31 executes a task transition setting process (S3), decrements the counter (S4), and ends this routine.

In S2, if the counter value is 2 or more (S2: YES), the CPU 31 does not execute the task transition setting process, proceeds to S4, decrements the counter, and ends this routine.

That is, in this task switching control process, the counter is incremented before the task transfer setting (S3) (S1), and after the task transfer setting (S3), the counter is decremented (S4). Therefore, the task transfer setting (S
If 3) is not interrupted, the content of the counter is always 1 at the start of the task transfer setting (S3), and the task transfer setting (S3) is executed to switch the task.

On the other hand, when the task transfer setting (S3) is interrupted by an interrupt higher than the timer interrupt, the content of the counter remains 1. Then, when the processing of the higher-order interrupt is completed and the interrupted task transfer setting (S3) is resumed, if a timer interrupt for task switching occurs,
As a result, the task transfer setting (S3) is interrupted again, and the task switching control process by a new timer interrupt is started. At this time, the task transition setting once resumed (S3)
Has not been completed yet, the content of the counter remains 1. Therefore, in the new task switching control process, the content of the counter is 2 at the start of the task transfer setting (S3), and the counter is decremented without executing the task transfer setting (S3) (S4). The content of the counter becomes 1. Thereafter, the rest of the suspended task transfer setting (S3) is resumed, the task is switched, the counter is decremented (S4), and the content of the counter becomes zero.

As described above, when the task switching processing by the timer interruption is nested, the task transition setting (S3) is not performed until the content of the counter becomes 1 or less, that is, until the nesting is canceled. Erroneous operation of task switching due to nesting of switching processing can be prevented.

In the above embodiment, the RAM 3
3 is realized by using the counter.
The counter may be realized by using a register (not shown) built in 31.

[0034]

As described above, according to the information processing apparatus of the first aspect, a certain number is added before the task switching process is started by the task switching means, and the fixed number is added after the task switching process ends. The counter means for decrementing the number and the task switching inhibiting means for inhibiting task switching in the task switching processing if the content of the counter means is equal to or more than a predetermined value at the start of the task switching processing. Accordingly, the occurrence of nesting can be detected, and when nesting occurs, task switching is prohibited until nesting is eliminated. Therefore, malfunction of task switching due to nesting of task switching processing can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating a state in which a multifunction peripheral device including an information processing device according to the present invention is connected to a personal computer.

FIG. 2 is a flowchart illustrating a procedure of a task switching control process performed by the information processing apparatus illustrated in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Personal computer 2 MFD 31 CPU 32 ROM 33 RAM 34 EEPROM 35 Gate array 38 Scanner 39 Printer 40 Modem 41 Operation part 42 Display part 51 Cable 54 Telephone line

Claims (1)

(57) [Claims] 1. An information processing apparatus capable of executing a multi-task process, comprising: a task switching unit for performing a task switching process by generating a timer interrupt; and a constant before the task switching process is started by the task switching unit. Counter means for adding a number and subtracting the fixed number after the task switching processing is completed; and when the content of the counter means is equal to or more than a predetermined value at the start of the task switching processing, An information processing apparatus comprising: a task switching prohibition unit that prohibits switching.