JP3087518B2 - Look-ahead data processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing apparatus, and an object of the present invention is to read data recorded in blocks on a medium as quickly as possible when reading data continuously.

[0002]

2. Description of the Related Art In recent years, multimedia orientation has advanced, and not only character information but also audio, image and video information has been required as data handled by computers such as personal computers. The voice,
CD (Comp) as a medium for easily recording image and video information
act-CD). CD-RO
M addresses data in units of blocks of about 2 KB, and random access is possible, but it is an effective medium if successive blocks are accessed sequentially.

FIG. 3 is a diagram showing the concept of data on a CD-ROM. The data is divided into blocks on a spiral track, and 2 KB data and its block address are assigned. When displaying moving images using a CD-ROM, it is necessary to read data at a high speed one after another. The processor prepares an appropriate reading area on the memory, and prepares an address of the first block and an address of the last block. Issue a read command to the controller by specifying the address. Since an excessively large area cannot be prepared, commands are continuously issued in image display or the like, and the received data is displayed one after another.

FIG. 4 shows the configuration of a conventional apparatus. FIG. 5 is a flowchart showing the concept of the look-ahead according to the related art. When the controller 2 that controls the drive 3 receives the read command from the processor 1, it determines whether or not the data requested by the processor 1 is in the prefetch buffer 4 according to the block address designated by the read command. (s1) If there is, data is transferred from the pre-read buffer 4 (s2). If not, a drive control command is issued (s5), and data is transferred from the drive 3 (medium 6). By the time you transfer data,
It takes time (search time) for positioning and rotation waiting of the read head (d1). Thereafter, the data of the designated block is directly transferred to the processor 1 without passing through the prefetch buffer 4 (d2, s7). After the transfer to the processor 1 is completed, the data of the subsequent block is stored in the prefetch buffer 4 (d2, s6, s8). Therefore, when data is continuously read from the CD, when the next read command is received thereafter, the data can be transferred from the pre-read buffer 4 to the processor 1, so that the waiting time can be absorbed. This is the pre-reading function, and is effective when data such as a moving image is read out by a read command every frame and displayed on a display.

[0005]

However, naturally, when there is no data in the prefetch buffer 4, when the data has not completely entered the prefetch buffer 4,
Since the data is read again from the drive 3 and the data is transferred, it takes the same waiting time as the normal data transfer when the data is not pre-read. Therefore, even if the timing of issuing the next read command from the processor 1 is too early. There has been a problem that data transfer is delayed for an application that requires high-speed data transfer.

According to the present invention, in consideration of the above problem, when the controller 2 receives a data read command from the processor 1, the data requested by the processor 1 is not in the prefetch buffer 4, but the prefetch control is being performed. Then, the purpose is to read out data as fast as possible by determining whether it is faster to transfer the data after entering the pre-read buffer 4 as it is.

[0007]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The processor 1 includes a processor 1, a controller 2, and a drive 3. The processor 1 specifies a block address of a medium and issues a read command to the controller 2.
The controller 2 checks if the data of the designated block address exists in the prefetch buffer 4 in the controller 2 and transfers the data from the prefetch buffer 4 to the processor 1 if it exists. Upon receiving the drive control command, the drive 3 searches for the block address of the medium, reads and sends the data, and the controller 2 receives the data and transfers the data to the processor 1, and transfers the specified amount of data. When it is over, the subsequent data is read ahead in buffer 4.
Is a data processing device that performs pre-reading control to be stored in the data storage device.

The controller 2 of such a data processing device is provided with a standby determination unit 5. The standby determination means 5
Although the data of the specified block address does not exist in the prefetch buffer 4 in the controller 2 , the prefetch control is being performed.
When it is determined that the data
Waits for data from the prefetch buffer 4 to the processor 1
Control to transfer .

[0009]

[0010]

The data specified by the standby judgment means is prefetching.
If it is determined that the controller 2 it final
Then , the data is transferred from the prefetch buffer 4 to the processor 1. Issue a new control command to drive 3
The processor 1 can receive data faster than it does.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where a medium is a CD and a controller 2 controls a CD drive 3 will be described with reference to the flowchart of the processing of the present invention in FIG. The controller 2 includes a microprocessor, a memory, and the like. 64 memories
If it is about KB, 1
About 0 KB is used, and the remaining 50 KB is used as the pre-reading buffer 4 to hold 25 or more 2 KB data blocks. The block address of the pre-read data is held in the block address area.

When the first read command is issued, there is no data in the pre-read buffer 4 yet, so the controller 2 issues a control command to the CD drive 3 and searches the specified address. After transferring data from there to the specified block,
The subsequent block data is stored in the prefetch buffer. It also records which block address of the CD the data put in the prefetch buffer is. Thereafter, if a read command specifying the address of the data existing in the prefetch buffer is received, the data is transferred from the prefetch buffer to the processor as in the conventional case. If the next read command is received from the processor 1 before the operation of storing the data in the prefetch buffer by the previous read command is completed, it can be determined that the requested data is not in the prefetch buffer (s1) but the prefetch is being performed (s3). ) So wait,
After entering the prefetch buffer (s4), it is transferred (s2).
Accordingly, high-speed data transfer can be performed because the time for searching (d1) data in the CD drive can be eliminated.

[0013]

As described above, according to the present invention,
When data is continuously transferred from the medium, restrictions on the issuance timing of the read command issued from the processor are reduced. As a result, high-speed data transfer can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a flowchart illustrating the operation of the present invention.

FIG. 3 is a diagram showing the concept of data on a CD-ROM.

FIG. 4 is a diagram showing a conventional device configuration.

FIG. 5 is a flowchart showing the concept of the look-ahead according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processor 2 Controller 3 Drive 4 Read ahead buffer 5 Standby judgment means 6 Medium

Claims (1)

(57) [Claims] When a processor issues a read command to a controller by designating a block address of a medium, the controller stores data of the designated block address in a prefetch buffer in the controller. Check if it exists, transfer the data from the prefetch buffer to the processor if it exists, and issue a drive control command to the drive if not, the drive receives the drive control command, searches the block address of the medium, reads the data, and The controller receives the data, transfers the data to the processor, and after transferring the specified amount of data, in the data processing device that performs the pre-reading control of storing the subsequent data in the pre-reading buffer, the controller is provided with standby determination means. The waiting judgment means Although data for the specified block address is not present in the look-ahead buffer in the controller, when it is determined that the system is in the prefetch control waits for the data to enter the look-ahead buffer, to transfer data from the prefetch buffer to the processor A look-ahead data processing device characterized by controlling .