JP3112709B2 - Access device for write-once storage medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for accessing a write-once storage medium which cannot physically modify or update stored data and additionally writes data in a storage area.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 20, a storage medium such as a hard disk (HD) or a floppy disk (FD) accesses storage data due to its nature and is located at the same storage location. It can be physically modified and updated easily. On the other hand, storage media such as optical discs (OD)
A so-called destructive writing method is employed, and data cannot be physically modified or updated at the same storage location due to its nature. If such correction or update is attempted, a write error will occur.

Therefore, in the conventional write-once storage medium access method, when the storage data is corrected or updated, the update data is not updated.
When writing the data to another unwritten area and adding the management table, or reading the updated data, the operator reads the management table on, for example, a display screen of a CRT and reads the latest data. It is configured to select update data.

[0004]

However, in the above-mentioned conventional write-once storage medium access method, the update data is not updated.
When reading the data, the operator reads the management table on, for example, a display screen of a CRT and selects the latest update data, so that the operator can correct and update the stored data. In addition, there is a problem that it is difficult to manage corrected data and updated data.

The present invention has been made in view of the above-mentioned conventional problems, and enables an operator to modify and update data stored in a write-once storage medium. It is an object to provide an access device for a write-once storage medium that can easily manage update data.

[0006]

According to the present invention, there is provided an apparatus for accessing a write-once storage medium, wherein at least one of a plurality of blocks of a first data storage area of a write-once storage medium is written last. If the data obtained by adding the additional data to the data of the first block does not satisfy one block, the data obtained by the addition is replaced with the first data.
If the data obtained by adding additional data to the last written data of the first block fills one block, the one block is filled. Writing means for writing the data for one minute into the second data storage area of the write-once type storage medium and writing the data for the one block exceeding the one block to the second block; and writing the data for the second data storage area to the second data storage area. Reading means for reading data, reading data from the last written block of the first data storage area, and combining the data read from the first and second data storage areas as the latest data. It is characterized by having.

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

According to the present invention, the writing means is a write-once type
Of the plurality of blocks in the first data storage area of the storage medium
Additional data is added to the last written data of the first block.
The data obtained by adding
If not, the additional data is stored in the first block.
Writes to the second block following the lock, while
Add additional data to the data of the first block
When the data obtained by filling up one block
Is the amount of data that satisfies the one block in the write-once storage medium.
Writing to the second data storage area and the block
Writing the excess data to the second block,
Reading means for writing to the second data storage area
Read out the data stored in the first data storage area
Read data from the last block written
And the data read from the first and second data storage areas.
Combine data and extract as the latest data. this
Therefore, the reading time can be reduced,
Data storage area of write-once storage media while improving
Can be used effectively.

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

The following examples of the present invention will further clarify such effects of the present invention, and further clarify other effects of the present invention.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an apparatus for accessing a write-once type storage medium according to the present invention, FIG. 2 is an explanatory view showing a storage area of an optical disk of the storage apparatus of FIG. 1, and FIG. FIG. 4 is an explanatory diagram showing the addresses of the storage areas, and FIG. 4 is a flowchart for explaining the operation of the access device for the write-once storage medium of FIG.

In FIG. 1, a CPU (Central Processing Unit) 11
Processes data and commands input through the keyboard 12, and controls the display of the CRT 13 and the writing and reading of the memory 15 through the control circuit 14. The CPU 11 also processes data read by the scanner 17 through an I / F (interface) circuit 16, controls writing and reading of a write-once storage device 18, and controls the printer 19. Control printing. The memory 15 is, for example, a RAM
(Random access memory), storage device
Reference numeral 18 includes, for example, an optical disk (OD) and its driving device.

The storage area of each file F on the optical disk of the storage device 18 is composed of, for example, a minimum unit block B1 of 512 bytes or 1024 bytes, and one block B1 to an area of one file B of the file F. Data is stored. Note that the capacity of the blocks B1 to B1 differs for each storage medium.

The CPU 11 first receives each data file F in accordance with data or commands input via the keyboard 12.
Is fixedly assigned to the position and size of the area for storing the. In this case, if there are a plurality of files F to be handled, they are allocated for them, and the size is determined in consideration of the predicted number of updates.

When data is stored on the optical disk, the data is stored from the first block B1 in the area of the file F. When updating the stored data, the CPU 11
First, the stored data is read out from the optical disk to the memory 15 and displayed on the screen of the CRT 13 and corrected on the memory 15 in accordance with the data and commands input via the keyboard 12.
Then, when registering this update data on the optical disc,
As shown in FIG. 2, the data is transferred from the memory 15 to the optical disk, and is written last in the data storage area (data allocation area) constituting the file F in the entire data storage area 101 of the optical disk. The block Bn + 1 next to the block Bn is registered. When data is updated on the file F in this manner, the written area F1 becomes larger and the unwritten area F2 becomes smaller.

Next, the detailed operation of the updating process and the updating data reading process will be described with reference to FIGS.
In FIG. 3, T is the start address of the file F,
Y is the last address of the written area F1 of the file F, and X is the start address of the unwritten area F2 of the file F.

In the updating process, first, an address T indicating the position of the first block B1 of the file F is set to the read address n (step S1 in FIG. 4), and the data of the read address n is read from the optical disk. It is stored in the memory 15 (step S2). Next, it is determined whether or not the area of the read address n is in the unwritten state (area F2) (step S3). If not, the read address n is incremented (step S4) and step S2 is performed.
Then, the area F2 in the unwritten state is searched. In step S4, it is preferable to check the size of the data area of the file F.

When the area F2 in the unwritten state is obtained, the process branches from step S3 to step S5, where the read address n is set to the write address X of the update data. Address T
It is determined whether or not the value is greater than (step S6). If n> T, the read address n is decremented by one (step S7), the read address n is set to the last address Y of the stored data (step S8), and then the start address X of the unwritten area F2 is set. The updated data is stored in the area of. In step S7, it is preferable to check the storage data in consideration of the write error.

If it is determined in step S6 that n.ltoreq.T, the optical disk is in a completely unwritten state.
Then, the last address Y of the stored data is set to the address "0", and the data is stored in the area of the write address X.

When reading the updated data, the data is sequentially read from the area of the write address T, and the unwritten area F2 next to the latest updated data is searched.
The data of the written area F1 before this unwritten area F2
Write area by judging whether the data is valid
Read the latest update data of F1.

Therefore, according to the above embodiment, the CPU 11 reads the data written on the optical disk, searches the unwritten area F2 next to the written area F1, and updates the unwritten area F2 with the updated data. Data is sequentially written and the latest update data is read out by searching the write area F1 of the latest update data written in the data area of the optical disk. Can be corrected and updated, and the corrected data and updated data of the optical disk can be easily managed. In this case, the history of the update data can be managed, which is convenient.

In the above embodiment, when the area of the update data is obtained, the search is started from the first write address of the file F (steps S1 to S4). The search may be performed from the write address.

In the above embodiment, a non-rewritable storage medium such as an optical disk has been described as an example.
If the present invention is applied to a rewritable storage medium such as a hard disk, update data can be sequentially added without erasing the storage data. History can be managed and stored data
Data security. In this case, if a flag indicating an unwritten state is set in a predetermined area of each block of the storage medium, the unwritten area is supported.
Touch processing can be simplified.

Next, a second embodiment of the present invention will be described with reference to FIGS.
An example will be described. FIG. 5 is an explanatory diagram showing a storage area of an optical disk in a second embodiment of the write-once type storage medium access apparatus according to the present invention, FIG. 6 is an explanatory diagram showing addresses of the storage area in FIG. 5, and FIG. 7 is a flowchart for explaining the operation of the write-once type storage medium access device of the second embodiment. In the first embodiment, one block B1 ~
Data is written to each block, so that one block B1
Although it is not possible to write data with a capacity exceeding
The present embodiment is configured to be able to process data D having a capacity exceeding one block B1.

As shown in FIG. 6A, the storage area of each file F on the optical disk of the present embodiment is, for example, in units of blocks B1 to 512 bytes or 1024 bytes, which is the minimum unit, as in the first embodiment. However, when the write data D has a capacity of a plurality of blocks B1 to B1, the data is written continuously to each of the blocks B1 to B, and the data size and the start position (pointer S) are added at the end of the write data D. ) Is written. Update data
The general operation of writing the data D is the same as that of the first embodiment, and a detailed description thereof will be omitted.

Next, an operation for reading the update data D will be described with reference to FIGS. First, FIG.
In step S11 shown in FIG. 7, the stored data is sequentially read out for each block B1 to B1 and stored in the memory 15.
, The data of the last management data (address Y)
Search for the data size and the pointer S.
All the latest data D is read by the pointer S.

Therefore, in this embodiment, when the write data D has a capacity of a plurality of blocks B1 to
Since the management data including the data size and the start position (pointer S) is written at the end of the write data D at the end of the write data D, the data D having a capacity exceeding one block B1 is written. Can be processed.

As shown in FIG. 6B, in an actual system, in order to cope with an error or the like, a pointer indicating the next block of valid data in a data start block. It is preferable to have

Next, a third embodiment will be described with reference to FIGS. FIG. 8 is an explanatory diagram showing a DMA (Direct Memory Access) transfer in a third embodiment of the write-once storage medium access device according to the present invention, and FIG. 9 is a diagram for explaining the operation of the third embodiment. This is a flowchart.
In the second embodiment, all the stored data in the written area F1 is read out to the memory 15 and the head address of the unwritten area F2 is searched, so that the ready check time, seek time, etc. Although the processing time of the CPU 11 becomes longer, this embodiment is configured so as to reduce the processing time of the CPU 11 by adding a DMA controller.

First, as shown in FIG. 8, a buffer area (capacity M) of the memory 15 for storing the storage data of the optical disk is secured. The buffer area is desirably large enough to store all data in the allocated area of the optical disk. However, if the capacity of the system is limited, it is preferable that the buffer area be as large as possible.

Next, in FIG. 9, the start block position T (n ← T) of the file F (step S21), the read data amount H (h ← H) of the file F and (step S22)
), And sets the buffer capacity M (m ← M) of the memory 15 (step S23). Next, when the set buffer capacity m is larger than the read data amount h, the read data amount h is set to the buffer capacity m (step S2).
4, S25), so that all the data of the file F are DMA-transferred from the optical disk to the buffer area of the memory 15.
The MA controller is controlled (step S26).

Therefore, during this reading time, the CPU 11
Can perform other processing. This step
In S26, the DMA controller determines the current read processing block amount a (≦ m) and the last read position (error
Is returned to the CPU 11 as an error occurrence position) b.

Here, if all the data is read without any error, no unwritten block exists in the allocated area of the file F.
On the other hand, when an error occurs, the data in the unwritten area F2 may be read and the data in the written area F1 may be read.
It can be determined by the status. Therefore, in the former case, the block in which the error has occurred is the first block of the unwritten area F2. In the latter case, the unwritten area F2 can be searched by reading out the data further. it can.

In FIG. 9, if an error has occurred, the flow advances from step S27 to step S28 to proceed to the unwritten position.
It is determined whether it is F2 or not, and if it is not the unwritten position F2, the process proceeds to step S29, where the current read processing block amount a is set as the buffer capacity m of the memory 15 and the step S3
Go to 0. If no error occurs, step S2
From step 7, go directly to step S30.

In step S30, the read data amount h is set to the remaining read amount (= hm), and step S2 is executed.
Return to step 3 and read the remaining data. Step S30
, The read data amount h is equal to the remaining read amount (h
If −m), the update data cannot be written because the unwritten position F2 does not exist on the optical disk. In step S28, in the case of the unwritten position F2, since the error occurrence position is the start position of the unwritten area F2 as described above, the error occurrence position b is changed to the head write position of the update data. Set to (Step
S31).

Therefore, according to the above embodiment, since the storage data is transferred from the optical disk to the memory 15 by the DMA controller, the head write position of the update data can be searched in a short time. Ready, ready check time and
The processing time can be shortened by omitting the lock time and the like.
The processing efficiency can be improved even when the amount of storage data is small, and the CPU 11 can execute other processing during the DMA transfer.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10A is an explanatory view showing the storage area of the optical disc in the first to third embodiments, and FIG.
FIG. 14 is an explanatory diagram showing a storage area of an optical disc in a fourth embodiment.

As shown in FIG. 10A, in the first to third embodiments, the storage area of the optical disk is fixedly allocated for each file F, so that the storage area is full of update data. , New update data cannot be written. Therefore, if there is a file that is frequently updated according to the user, the update data cannot be written even though there is a free area.

Therefore, in the present embodiment, in such a case, the update data can be written by effectively utilizing the free space. As shown in FIG. 10B, at the head of the storage area, a management table 20 of an appropriate size is secured from the first block.
Reference numeral 20 denotes the start block position and size (or end block position) of each file F. The management table 20 can be changed as described later.
In FIG. 10B, it is fixedly assigned.

The data area of each file F is secured sequentially in an area following the management table 20 with an appropriate size (minimum size for normal use + α), and an unused spare area 21 is secured in a rear area. Is done. Then, as shown in the first to third embodiments, the updated data is added to the area of the file F, and when the area of the file F becomes full, the new updated data is written to the spare area 21. Also, the management table 20 is updated and added.

Therefore, according to the present embodiment, since the update data is written in the spare area 21 of the optical disk, it is possible to write the update data when there is a file which is frequently updated according to the user. it can. In this embodiment, the spare area
Although the update data is written in 21, the update data may be written in the free area F2 of another file where the update does not occur frequently.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory diagram showing the storage area of the optical disc in the fifth embodiment. In the fourth embodiment, the data area of each file is fixed and secured sequentially. In this embodiment, the data area of each file A and B is updated without updating the data area. Regardless of the files A and B, it is configured to be additionally written and managed by the management table 20.

As shown by reference numeral 20a in FIG. 11, an area of an appropriate size is secured for the management table 20 from the first block of the optical disk, and the data area of each of the files A and B follows this area. Is secured without being fixed. In the management table 20, an initial value "0" of the start block position and size (or end block position) of each of the files A and B is written. Then, as shown in FIG. 20b, the data of the files A and B are added to the data area and the management table 20 is updated, and the updated data of the files A and B are updated as shown in 20c. Then, the management table 20 is updated by being added to the data area in the updating order.

That is, in the fourth embodiment, since the data area of each file F is sequentially fixed and secured, a useless data area is generated. However, in the fifth embodiment, the data area is updated. Since data is additionally written irrespective of files A and B, the data area of the optical disk can be effectively used, and the unwritten position F2 can be searched at high speed by the management table 20. Can be. If the power is turned off while the update data is being written, the management table 20 is not destroyed, so that the update data can be written again.

Next, the sixth embodiment of the present invention will be described with reference to FIGS.
An example will be described. FIG. 12 is an explanatory diagram showing the updating process of the first to fifth embodiments, FIG. 13 is an explanatory diagram showing the updating process of the sixth embodiment, and FIG. 14 is an updating diagram of the sixth embodiment. FIG. 9 is an explanatory diagram showing a data reading process. In the first to fifth embodiments, as shown in FIG.
In this embodiment, the configuration is such that all
As shown in FIG. 13, data a is modified to data b, and data
When the data x is corrected to the data y, only the correction data b and y are added to the update area F3, and the management information exclusive management data of only the correction data b and y is added. It is configured as follows.

When reading the update data, the management table and the management data dedicated to the change information are used, and as shown in FIG. If the data is insufficient, the storage data is read out to a storage medium that can be physically modified and updated, such as a hard disk, and the latest data is managed by the change information dedicated management data.
Expand to Therefore, according to this embodiment, only the correction data b and y are added without writing all the update data of the file A, so that the data area of the optical disk can be used more effectively.

Next, a seventh embodiment of the present invention will be described with reference to FIGS.
An example will be described. FIG. 15 is an explanatory diagram showing a general write process, FIG. 16 is an explanatory diagram showing a process of reading update data written by the process of FIG. 15, and FIG. 17 is another general write process. FIG. 18 is an explanatory diagram showing the storage area of the optical disc in the seventh embodiment, and FIG.
FIG. 19 is an explanatory diagram showing a writing process in the seventh embodiment.

In general write processing, as shown in FIG. 15, when data a to d are written for each of the blocks B1 to B4, an empty area is generated in each of the blocks B1 to B4. When additional data e is additionally recorded, an empty area is generated in the block B5. And such data a to e
When reading into the memory 15, as shown in FIG.
The data is sequentially read in a state where the data a to e are packed in consideration of the free area of each block B1 to B5 by the management table.

In another general write process, as shown in FIG. 17, when data s and t are written in one block B1 and the next data u is written in the next block B2,
When an empty area is generated in the block B2 of the data u, and when additional data w is written, all the updated data s to w
Is added to the following blocks B3 and B4. When such data s to w are to be read into the memory 15, the updated data s to w added to the blocks B3 and B4 are read.

In the writing method as shown in FIG. 15, it takes a long time to read since the empty area of each of the blocks B1 to B5 is taken into account in the case of reading, and in the writing method as shown in FIG. Blocks B3,
Although the storage area is wasted because it is added to B4, in the seventh embodiment, as shown in FIG. 18, a temporary area F4 for temporarily storing data and a The data area is divided into two areas, ie, a normal area F5 for storing data, and the data area is effectively used by shortening the reading time.

In FIG. 19, data less than a block
When writing the data a, an empty area is provided and written to the block B1 of the temporary area F4. When writing the data b whose total amount with the data a is less than one block, a free area is provided and the data a, b are stored in the block B2 next to the temporary area F4.
Write b. When writing data c whose total amount of data a and b exceeds one block (= data c 'which reaches one block + remaining data c "), data of one block is required. -Blocks a, b, c 'in the normal area F5
At the same time as writing to B1, the remaining excess data c "is written to the block B3 next to the temporary area F4 with a free area provided.

Similarly, when writing the data d whose total amount with the data c "is less than one block, an empty area is provided and the data c" is stored in the block B4 next to the temporary area F4. ,
Write d. Then, when writing data e in which the total amount of data c "and d exceeds one block (= 1 data e 'which reaches up to one block + remaining data e"), one block worth of data is written. The data c ", d and e 'are written in the block B2 of the normal area F5, and the remaining excess data e" is provided with an empty area to provide the next block B5 of the temporary area F4.
Write to. When reading the write data a to e, the data a to d of the blocks B1 and B2 in the normal area F5 are read.
e ′ and the data e ″ of the block B5 in the temporary area F4 are read out.

That is, basically, when writing to the temporary area F4, data is added to the previous block and written.
The excess data is written in the block of the temporary area F4 and the excess data is written in the block next to the temporary area F4.
The block data is written in the normal area F5. Therefore, the data area can be used effectively, and when reading the latest data, the data in the regular area F5 having no free area is read, so that the reading time can be reduced. .

In this embodiment, the temporary data area F4 and the normal data area F5 are not secured for each file, and the updated data is additionally written regardless of the file, as in the fifth embodiment. If it is configured to manage the data area, the data area can be used effectively. In this case, if a pointer indicating the latest write block position of each file is written in the block in the temporary area, the management is simplified.

[0065]

As described above in detail, according to the present invention, the writing means stores the first data in the write-once storage medium.
Is the last of multiple blocks in the data storage area
Obtained by adding additional data to the data of the first block.
If the data does not fill one block,
The data obtained by the addition is added to the second block following the first block.
While writing to the block, the last block written to the first
Data obtained by adding additional data to the lock data
If one block is filled,
A second data storage area of a write-once type storage medium
Data written to the area and exceeding the one block
Is written in the second block, and the reading means
Reading the data written in the second data storage area
And at the end of the first data storage area
Read data from the first and second blocks.
Combining data read from data storage areas
Retrieve as the latest data. Therefore, the read time
Can be shortened, and readout can be performed while improving readout efficiency.
More effective use of the data storage area of the recordable storage medium
Can be.

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

As a result, the operator can correct and update the storage data of the write-once storage medium, and easily manage the correction data and update data of the write-once storage medium. An extremely convenient write-once type storage medium access method can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus for accessing a write-once storage medium according to the present invention.

FIG. 2 is an explanatory diagram showing a storage area of an optical disk of the storage device of FIG.

FIG. 3 is an explanatory diagram showing addresses of storage areas in FIG. 2;

FIG. 4 is a flowchart for explaining the operation of the write-once storage medium access device of FIG. 1;

FIG. 5 is an explanatory diagram showing a storage area of an optical disc in a second embodiment of the write-once storage medium access device according to the present invention.

FIG. 6 is an explanatory diagram showing addresses of storage areas in FIG. 5;

FIG. 7 is a flowchart for explaining the operation of the write-once type storage medium access device of the second embodiment.

FIG. 8 is an explanatory diagram showing DMA (direct memory access) transfer in a third embodiment of the write-once storage medium access device according to the present invention.

FIG. 9 is a flowchart for explaining the operation of the third embodiment.

FIG. 10 is an explanatory view showing a fourth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a storage area of an optical disc in a fifth embodiment.

FIG. 12 is an explanatory diagram illustrating an update process according to the first to fifth embodiments.

FIG. 13 is an explanatory diagram illustrating an update process according to the sixth embodiment.

FIG. 14 is an explanatory diagram showing a process of reading updated data according to the sixth embodiment.

FIG. 15 is an explanatory diagram showing a general writing process.

FIG. 16 is an explanatory diagram showing a process of reading updated data written by the process of FIG. 15;

FIG. 17 is an explanatory diagram showing another general write process.

FIG. 18 is an explanatory diagram showing a storage area of an optical disc in a seventh embodiment.

FIG. 19 is an explanatory diagram showing a writing process in a seventh embodiment.

FIG. 20 is an explanatory diagram showing a storage medium update process capable of physically correcting and changing storage data.

[Explanation of symbols]

 11 CPU (central processing unit) 18 Storage device (optical disk)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-39316 (JP, A) Jeffrey R. Durude, “Application interface for write-once optical discs”, Nikkei Byte, Nikkei McGraw-Hill, No. . 24, September 1, 1986, p. 111-118 (58) Field surveyed (Int. Cl. ⁷ , DB name) G06F 12/00 G06F 3/08

Claims (1)

(57) [Claims] 1. A data obtained by adding additional data to data of a last block of a first block among a plurality of blocks of a first data storage area of a write-once type storage medium which fills one block. If not, the additional data is written to the second block next to the first block, while the additional data is added to the data of the last written first block. When the data reaches one block, the data that satisfies the one block is written into the second data storage area of the write-once type storage medium, and the data that exceeds the one block is written into the second data storage area.
Writing means for writing data to the second data storage area; reading data written to the second data storage area and reading data from the last written block of the first data storage area; An access device for a write-once type storage medium, comprising: reading means for combining data read from a data storage area and extracting the latest data.