Method for controlling memory card and method for controlling nonvolatile semiconductor memory

• US 8,065,473 B2
• Filed: 06/10/2010
• Issued: 11/22/2011
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ito, Takafumi, Sakamoto, Hiroyuki
• Primary Examiner(s): PATEL, HETUL B
• Application Number:
  US12/813,164
• Publication Number:
  US 20100250839A1
• Time in Patent Office: 530 Days
• Field of Search: 711/103, 711/703, 711/E12.006
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0626 Reducing size or complexity of storage systems
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A method for controlling a memory card which includes a nonvolatile semiconductor memory whose memory area includes a plurality of write areas is disclosed. A first area which is a part of the plurality of write areas is set in accordance with management executed by a first file system. The first file system sequentially writes data along a direction in which addresses of the plurality of write areas increase. A second area which is a part of the plurality of write areas is set in accordance with management executed by a second file system. The second file system writes data in an order which does not depend on the addresses.

Claims

1. A method for controlling a memory card which includes a nonvolatile semiconductor memory whose memory area includes a plurality of write areas, the method comprising:

formatting a first area which is a part of the plurality of write areas in accordance with management executed by a first file system which sequentially writes data along a direction in which addresses of the plurality of write areas increase; and

formatting a second area which is a part of the plurality of write areas in accordance with management executed by a second file system which writes data in an order which does not depend on the addresses;

creating a temporary file entry describing a size of a reserved region which is at least a free part of the plurality of write areas and a start position of the reserved region;

writing a file of a plurality of data in the reserved region from the start position after creating the temporary file entry; and

when the file has been completely written, determining a size of the file written and writing a final file entry describing the start position and the size of the file by writing the final entry based on the determined size of the file or overwriting the temporary file entry as the final file entry based on the determined size of the file; and

when the file has not been completely written, referencing the temporary file entry to recognize the start position;

detecting a final position in the reserved region, in final position data partly constituting an unfinished file which is a part of the file being written;

determining a size of the unfinished file using the start position and the final position; and

changing the temporary file entry to a final file entry describing the start position and the size of the unfinished file.

2. The method according to claim 1, wherein sequentially writing data along a direction in which addresses of the plurality of write areas increase includes continuously writing data in the plurality of write areas having consecutive addresses.

3. The method according to claim 1, wherein the first file system is one of a DVD-R type file system, a DVD-RW type file system, and a DVD-RAM type file system, and

the second file system is a FAT file system.

4. The method according to claim 1, wherein a host into which the memory card is inserted sets the first area in accordance with the management executed by the first file system and sets the second area in accordance with the management executed by the second file system.

5. The method according to claim 1, wherein the first area includes an region which a user can use, and the second area includes an region in which management information in the nonvolatile semiconductor memory is stored.

6. The method according to claim 1, wherein a data erasure is performed in units of erase areas each having a plurality of write areas in the nonvolatile semiconductor memory, and

the first file system recognizes a size of the plurality of erase areas and manages data taking the erase area into account.

7. The method according to claim 1, further comprising:

writing a partition table in the leading write area of the write areas, the partition table including information describing the leading write areas of the write areas in each of the first and second write areas and file system type of each of the first and second write areas.

8. The method according to claim 1, wherein the reserved region consists of a plurality of write areas having consecutive addresses, and

writing the file in the reserved region includes continuously writing data constituting the file in the plurality of write areas having consecutive addresses, along a direction in which the addresses increase.

9. The method according to claim 1, wherein each of the plurality of write areas has a data storage section which stores data and a written state information section which indicates a written state or a free state, and

writing the file in the reserved region includes writing data in the data storage section of one of the plurality of write areas and writing a written state indication in the written information section, and

detecting the final position includes referencing the written state information section to detect the final position.

10. A method for controlling a nonvolatile semiconductor memory whose memory area includes a plurality of write areas, the method comprising:

using a first control method to control the nonvolatile semiconductor memory when writing or reading data to or from a first area which is a part of the plurality of write areas, the first area being formatted in accordance with management executed by a first file system which sequentially writes data along a direction in which addresses of the plurality of write areas increase;

using a second control method to control the nonvolatile semiconductor memory when writing or reading data to or from a second area which is a part of the plurality of write areas, the second area being formatted in accordance with management executed by a second file system which writes data in an order which does not depend on the addresses;

creating a temporary file entry describing a size of a reserved region which is at least a free part of the plurality of write areas and a start position of the reserved region;

writing a file of a plurality of data in the reserved region from the start position after creating the temporary file entry; and

when the file has been completely written, determining a size of the file written and writing a final file entry describing the start position and the size of the file by writing the final entry based on the determined size of the file or overwriting the temporary file entry as the final file entry based on the determined size of the file; and

when the file has not been completely written, referencing the temporary file entry to recognize the start position;

detecting a final position in the reserved region, in final position data partly constituting an unfinished file which is a part of the file being written;

determining a size of the unfinished file using the start position and the final position; and

changing the temporary file entry to a final file entry describing the start position and the size of the unfinished file.

11. The method according to claim 10, wherein the first file system is one of a DVD-R type file system, a DVD-RW type file system, and a DVD-RAM type file system,

a data erasure is performed in units of one of a plurality of erase areas each having a plurality of write areas, and

the first control method includes avoiding copying data in one of the plurality of erase areas to another one of the plurality of erase areas.

12. The method according to claim 10, wherein each of the plurality of write areas has a data storage section which stores data and a written state information section which indicates a written state or a free state, and

a controller which controls the nonvolatile semiconductor memory writes data to the data storage section of one of the plurality of write areas and writes a written state indication in the written state information section.

13. The method according to claim 12, wherein the written state information section is used to detect one of the plurality of write areas in which data is written.

14. The method according to claim 10, wherein

each of write areas includes a data storage section which stores data and a written state information section which indicates a written state or a free state,

the method further comprises to sequentially write data in the plurality of write areas in a direction in which addresses of the plurality of write areas increase, while writing data in the data storage section of one of the plurality of write areas and writing a written state indication in the written state information section.

15. The method according to claim 13, wherein sequentially writing data in the plurality of write areas along a direction in which addresses of the plurality of write areas increase includes continuously writing data in the plurality of write areas having consecutive addresses.

16. The method according to claim 10, further comprising:

writing a partition table in the leading write area of the write areas, the partition table including information describing the leading write areas of the write areas in each of the first and second write areas and file system type of each of the first and second write areas.

17. The method according to claim 10, wherein the reserved region consists of a plurality of write areas having consecutive addresses, and

writing the file in the reserved region includes continuously writing data constituting the file in the plurality of write areas having consecutive addresses, along a direction in which the addresses increase.

18. The method according to claim 10, wherein each of the plurality of write areas has a data storage section which stores data and a written state information section which indicates a written state or a free state, and

writing the file in the reserved region includes writing data in the data storage section of one of the plurality of write areas and writing a written state indication in the written information section, and

detecting the final position includes referencing the written state information section to detect the final position.