JP3445848B2 - Buffer control method for external storage device - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] Field of the Invention The present invention relates to buffer control how the external storage device using a multi-task system. 2. Description of the Related Art Conventionally, an external storage device such as an optical disk device or a magnetic disk device has a device having a buffer memory for temporarily storing data read from each medium. Further, some of these apparatuses have a function of dividing a buffer memory into a plurality of sections and storing the data in each section according to the attribute of a data block reproduced from a medium. For example, Japanese Patent Application Laid-Open No. 60-206 discloses a device in which an audio data block and a still image data block are assigned respective identifiers and are separately stored in a buffer when reading from a medium.
No. 388 discloses this. [0003] In addition, when storing in a medium, using a task priority process of a multitasking system, the storing process and the process of determining the storage destination are performed by different tasks.
It is described in JP-A-2-173983. However,
The method described in this publication relates to replacement sector processing that occurs when writing to a medium. [0004] In the conventional apparatus and method, the storage destination is separated based on a predetermined identifier, or the data storage destination is determined based on a predetermined algorithm. For example, the case where the storage destination is changed in real time by an instruction from the host CPU is not considered. An object of the present invention, the external storage device to be stored in the buffer was fractionally data reproduced from media, is to provide a buffer control how that can change the storage destination in real time. [0006] According to an aspect of the present invention the buffer control how the external storage apparatus according to a multitasking system to proceed simultaneously in a time division multiple tasks, resources only a single task is common A semaphore mechanism for restricting access, a mechanism for dispatching a task when the semaphore is released , a buffer section management table for reading data from the optical disk and managing which section stores the read data, and a buffer section A table management task for changing the contents of the management table in accordance with an instruction from the host CPU, and a built-in task for reading data from a medium and storing the data in the buffer partition according to the buffer partition management table are provided. The buffer partition management table is accessed after locking the semaphore.
Also, the table management task has a higher priority than the built-in task. According to the present invention, during execution of a built-in task,
When the host CPU receives an instruction to change the data storage destination, the storage of the data currently being stored has been completed.
Since the buffer partition management table can be updated by dispatching to the table management task, the data storage destination can be changed in real time. An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of an external storage device (hereinafter referred to as a CD-ROM drive device 120) using a CD-ROM disk as a medium and adopting the buffer management system according to the present invention. The CD-ROM drive device 120 includes an I / F circuit 104 for controlling communication with the host CPU 90, a CPU 103 for controlling each component shown in the figure according to instructions from the host CPU 90, a CD-RO
CD drive 107 for playing M disk 108, CD
CD-ROM data conversion circuit 105 for converting a reproduction signal obtained from drive device 107 into data, buffer 102 for storing the converted data, and mutual operation between buffer 102, CD-ROM data conversion device 105, and I / F circuit 104. And a DMA circuit 106 for transferring data. Host CPU 90
Is connected to the CD-ROM drive 1 via an I / F data bus 112 and an access signal 111 for controlling access to the I / F.
A command for controlling the operation is issued to 20. An outline of a process in which the host CPU 90 reads data from the CD-ROM drive device 120 will be described below.
The host CPU 90 writes a data read command to the I / F circuit 104 using the I / F data bus 112 and the access signal 111. The CPU 103 receives the read command from the I / F circuit 104 and controls the CD drive 107 via the drive control signal 117 to reproduce a predetermined position on the CD disk 108 and, at the same time, sends the CD-ROM data to the DMA circuit 106. The output of the conversion circuit 105 is set to be transferred to the buffer 102. The reproduced CD reproduction signal 116 is a CD-R
The data is sent to the OM data conversion circuit 105, where it is converted into data as a CD-ROM, and is sequentially transferred to the buffer 102 under the control of the DMA circuit 106. The CPU 103 reports the status of data storage in the buffer 102 to the host CPU 90 via the I / F circuit 104. The host CPU 90 sends a data transfer command to the CPU 103 at any time, and the CPU 103
The DMA circuit 106 is set to transfer data from the buffer 102 to the host CPU 90 via the I / F circuit 104. The buffer 10 of the CD-ROM drive device 120
2 will be further described with reference to FIG. The buffer 102 is divided into n sections as shown. The section management table 203 holds information on the order of storing data from the CD-ROM disk 108 in this section. The contents of the partition management table 203 are rewritten by the table management task 202 according to an instruction from the host CPU 90. The built-in task 201 refers to the partition management table 203 and stores the data in the buffer 10.
Write to the designated section of 2. The built-in task 20
1 reports to the host CPU 90 how far data has been stored. A semaphore 204 is provided so that rewriting of the table management task 202 in the partition management table 203 and reference from the embedded task 201 do not conflict. The processing flow of both tasks using the semaphore 204 will be described with reference to FIG. First, the table management task 202
Shows the procedure for updating the table in FIG. This process is executed when a table change command is issued from the host CPU 90. S1 locks semaphore 204 and S
If the lock is not established after checking at 1 ', dispatch is performed once, and control is returned to the system.
Wait for the task to be executed again with the release of 4, and return to S1. Note that S1 and S1 'are instructions that are not separated by interruption or the like. When the semaphore 204 is locked, the partition management table 203 is updated in S3, the semaphore 204 is released in S4, and a series of processing ends. Next, the process of storing data by the built-in task 201 will be described with reference to FIG. First, S
Wait for data to be storable at 10. When it becomes possible, the semaphore 204 is locked in S11, and the inspection is locked in S11 '. Return to Note that S11 and S11 'are instructions that are not separated by interruption or the like. When the semaphore 204 is locked, the sector number being stored is indicated to the host CPU 90 in S12, and the storage destination of the data is determined by referring to the partition management table 203 in S13.
In S14, data for one sector is stored in a predetermined section.
In step S15, the semaphore 204 is released, and in step S16, it is checked whether all the data has been stored. If there is still a sector to be stored, the process returns to S11. However, when all the data has been stored, the task is terminated and control is returned to the system. Normally,
The embedded task 201 is activated each time data of one sector is read from the CD-ROM disk 108. In the case shown in FIG. 5, a plurality of sectors must be stored. CD-R
When data is transferred from the OM data conversion device to the buffer 102, the data is not directly transferred to the partition, but is once transferred to the cache area 101, where data error detection / correction is performed, and then stored in the partition. The cache area 101 may be a part of the buffer 102 or an independent memory. Since there is usually no error, data of one sector can be stored in a partition while data of one sector is read from the CD-ROM disk 108 as shown in FIG. But,
As shown in (b), when there is an error in the read data, the next data is read out during the correction processing and is stored in the cache area 101.
In (c), when the correction is completed and the storage of the data is started, since the read data is already stored, the built-in task 201 has to store the data of a plurality of sectors. Referring to FIG. 4, a description will be given of a process of changing a partition to be stored on the way from the host CPU 90 while data of a plurality of sectors is being stored. First, when the reading of the sector data a and the error correction are completed, the built-in task 201 is executed.
Is started. In step b, the semaphore 204 is locked and storage processing is performed. The host CPU 90 confirms that the storage process of the sector number 1 has occurred in c, sends an instruction to store the sector number 2 in a different partition, and starts the table management task 202. Since the table management task 202 has a higher priority than the built-in task 201, it is started immediately. However, since the semaphore 204 is already locked, the table management task 202 dispatches the table management task d to the built-in task 201. The built-in task 201 releases the semaphore 204 at the time e when the data storage operation in the partition is completed. When the semaphore 204 is released, the table management task 202 is started and the partition management table 203 is updated. During that time, the built-in task 201 which has been interrupted because its priority is lower than that of the table management task 202 is started at the end g of the table management task 203, and the data of the next sector is updated based on the updated partition management table 203. And store. With the above operation, data can be stored in an arbitrary partition in real time based on a command from the host CPU 90. According to the present invention, the data storage destination in the buffer can be changed at any time while the data is being read from the disk, so that the operability is improved. Further, according to the present invention, in an external storage device such as a CD-ROM disk device having a long waiting time until data retrieval, the sector is continuously reproduced without re-accessing the disk every time the buffer section is switched. Since data can be stored in arbitrary buffer sections in units, there is an effect of improving the data reproduction speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of an operation of a buffer management system according to the present invention. FIG. 2 is a flowchart showing processing of a buffer management type task according to the present invention; FIG. 3 shows a CD-R to which the buffer management method according to the present invention is applied.
FIG. 2 is a block diagram of an external storage device using an OM disk as a medium. FIG. 4 is an explanatory diagram showing task switching. FIG. 5 is an explanatory diagram showing a state of data managed by a built-in task. [Description of Signs] 90: Host CPU, 101: Cache area, 102: Buffer, 103: CPU, 104: I / F circuit, 105: CD-ROM data conversion circuit, 106: DMA circuit, 107: CD drive, 108 ... CD-ROM disk, 201: built-in task, 202: table management task, 203: partition management table.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirofumi Tsujimura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Video Media Research Laboratory, Hitachi, Ltd. (72) Inventor Setsuhiro Fukuyama 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa JP-A-3-28944 (JP, A) JP-A-4-85652 (JP, A) JP-A-5-282185 (JP, A) JP 60-19260 (JP, A) JP-A-2-264335 (JP, A) JP-A-2-79140 (JP, A) JP-A-3-113626 (JP, A) JP-A-4-288615 (JP, A A) JP-A-2-238546 (JP, A) JP-A-61-187060 (JP, A) JP-A-2-62623 (JP, A) JP-A-4-264940 (JP, A) JP-A-4 -270432 (JP, A) JP-A-5-282105 (JP, A ) Patent flat 2-173983 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) G06F 9/46 - 9/54 G06F 3/06 - 3/08 G06F 12/08 - 12 / 12 G06F 13/10-13/14 G06F 13/38-13/42

Claims (1)

(57) [Claim 1] In response to a command from a host CPU, data read from an optical disc is sorted according to its attribute,
An external storage device that stores data in an internal designated buffer partition. A partition that indicates in which partition the data read from the optical disk is stored according to the attribute of the data using a multitasking system that progresses multiple tasks simultaneously in a time-division manner. A management table, a semaphore for making access to the partition management table unique, a table management task for changing the partition management table in accordance with a partition designation command from the host CPU, and data read in accordance with a data read command from the host CPU. A built-in task for sorting data and storing data in a specified buffer partition; anda buffer control method for an external storage device that stores data in a buffer according to the following. According to the instruction, after locking the semaphore, Changing the partition management table, the embedded task locks the semaphore according to a data read command from the host CPU, and then stores the read data in a specified partition by referring to the partition management table. A buffer control method for an external storage device.