JP2009205591A - Access module, information recording module, and information recording system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for increasing seek processing speed when the nonvolatile memory of an information recording module is managed in terms of area by a FAT file system, and easily maintaining consistency in area management information. <P>SOLUTION: An access module 1 stores an extension FAT in a file system which manages the nonvolatile memory of the information recording module 2. The access module includes an extension FAT processing part 104 for performing area management by either normal FAT entries or extension FAT entries which are stored in the extension FAT with reference to the extension FAT. When file data is stored in continuous areas, the extension FAT entries are used so as to collectively manage the continuous areas with a small amount of information through area management by the extension FAT processing part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an access module, an information recording module, and an information recording system that store data in a nonvolatile memory and manage the data as a file.

  There are various types of recording media for recording digital data such as music content and video data, such as magnetic disks, optical disks, and magneto-optical disks. Among these recording media, memory cards that use a semiconductor memory such as a flash ROM as a recording element can rapidly reduce the size of the recording medium. Therefore, the memory card is rapidly used mainly for small portable devices such as digital still cameras and mobile phone terminals. It is popular. More recently, semiconductor memories such as flash ROMs are built into devices and used in place of hard disks. For example, they can be used not only as removable media such as conventional memory cards, but also as devices built-in storage. Semiconductor memory has come into use.

  For such a memory card or a device built-in storage, a semiconductor element called a NAND flash memory is mainly used. The NAND flash memory is a recording element that can once erase already recorded data and then record another data again, and forms an information recording device that can be rewritten a plurality of times, similar to a conventional hard disk. Is possible.

  Conventionally, data stored in a memory card or device built-in storage is managed by a file system. By managing data with a file system, it becomes possible to share data as a file between devices that interpret the same file system, and users can easily reference their stored data among multiple devices, It is possible to copy.

  Conventionally, the most widely used file system is called a FAT file system. The FAT file system has a feature that the area management is centrally managed by a table called a file allocation table (FAT). Since the structure is relatively simple and easy to implement, a flexible disk, a PC hard disk, or a memory card is used. It is widely used as a file system.

  FIG. 2 shows the configuration of the FAT file system. In the FAT file system, there are types such as FAT12, FAT16, and FAT32 depending on the bit width of the management unit in the file allocation table. However, the area management method using the file allocation table is almost the same. In the following, FAT16 is taken as an example. explain. As shown in the figure, at the head of the logical address space, there is a file system management information area 201 that is an area for storing file system management information such as an area allocation unit and the size of the area managed by the file system. . This file system management information area 201 includes file system management information called a master boot record / partition table 203, partition boot sector 204, FAT (205, 206), and root directory entry 207. Information necessary for management is stored. The master boot record / partition table 203 is an area in which information for managing an area on the logical address space managed by the file system by dividing it into areas called partitions is stored. The partition boot sector 204 is an area in which management information in one partition such as the size of the area management unit in the partition is stored. The FAT (205, 206) is an area in which information regarding the storage position of data included in a file is stored. Usually, there are two FAT (205, 206) having the same information, and one FAT (205, 206). Even if 206) is damaged, it is duplexed so that the file can be accessed by the other FAT (205, 206). The root directory entry 207 is an area in which information (directory entry) of files and directories existing directly under the root directory is stored.

  In the FAT file system, a user data area 202 for storing file body data and the like exists in an area subsequent to the file system management information area 201. The user data area 202 is divided and managed for each management unit called a cluster having a size of about 512 bytes to 32 KB, and data contained in a file is stored in each cluster. A file storing a lot of data stores data across a plurality of clusters, and the connection between the clusters is managed by link information stored in the FAT (205, 206). In addition, information (directory entry) on files and subdirectories existing in the directory immediately under the root directory is stored using a part of the user data area 202.

  FIG. 3 is a diagram showing the structure of the directory entry of FAT16. The directory entry 208 is assigned a 32-byte directory entry 208 for each file and directory, and stores information on the file and directory. That is, every time one file or directory is added, information of a 32-byte directory entry 208 is newly created and recorded in the area of the root directory entry 207 or the user data area 202. In the first 8 bytes of the directory entry 208, the name of the file or directory is stored. The extension is stored in the following 3 bytes. The subsequent 1 byte stores attribute information such as a flag for identifying the type of the file / directory and a flag for identifying whether the file / directory is read-only. Further, information on the last update date / time of the file / directory, the start cluster number indicating the start position of the cluster in which the substance of the file / directory data is stored, the number of bytes of the file size and the like are stored. As described above, the directory entry 208 includes only information indicating the position of the first cluster in the area in which the data entity is stored, and the second cluster when the size of the data entity is larger than one cluster. The area in which subsequent data is stored is managed by FAT (205, 206).

  FIG. 4 is a diagram showing the configuration of FAT (205, 206) of FAT16. In FAT16, FAT (205, 206) manages information of 2 bytes (16 bits) as one FAT entry, and one FAT entry indicates the state of one cluster. That is, when there are M clusters in the user data area 202, there are M FAT entries, so the size of one FAT (205, 206) is about 2 × M bytes. However, since the fixed value (0xF8FF, 0xFFFF) indicating the beginning of the FAT is recorded as the signature for the first 2 FAT entries, the FAT entry corresponding to the first cluster in the user data area 202 is 4 bytes of FAT (205, 206). The second and fifth bytes are present. Assuming that the 4-byte signature existing at the beginning of the FAT is 0 and 1 of the FAT entry, the position of the 2nd byte of the 4th and 5th bytes is second, so the top cluster of the user data area 202 is For convenience, cluster number = “2” is assigned, and there is no cluster corresponding to cluster number = “0”, “1”.

  Furthermore, each FAT entry indicates the status of the corresponding cluster (in use, available, defective) and the cluster number of the link destination. For example, in FIG. 4, the FAT entry for the corresponding cluster number 2 is set to 0x0003 (decimal number “3”), and the data subsequent to the data stored in the cluster with the cluster number 2 is within the cluster with the cluster number 3 It means that it is stored in. Similarly, the FAT entry of the corresponding cluster number 3 is set to 0x0004 ("4" in decimal), and the data subsequent to the data stored in the cluster of cluster number 3 is stored in the cluster of cluster number 4 Means that The FAT entry for the corresponding cluster number 6 is set to 0xFFFF. This means that the next link destination does not exist and the link is terminated. Therefore, in the example of FIG. 4, a series of file data is stored in the order of cluster numbers 2, 3, 4, 5, and 6. The FAT entry for the corresponding cluster number 7 is set to 0x0000. This means that the corresponding cluster is not used and is in an “empty” state. The FAT entry for the corresponding cluster number (M + 1) is set to 0xFFF7. This means that the corresponding cluster is in a defect state, such as a state in which recording is not possible because the cluster is physically broken. In summary, the three FAT entry values 0x0000, 0xFFFF, and 0xFFF7 have special meanings, and the FAT entry values from 0x0002 to 0xFFF6 are used as the link destination cluster numbers. The other values from 0x0001, 0xFFF8 to 0xFFFE are reserved and are not normally used.

  As described above, in the FAT file system, when file data is stored across a plurality of clusters, the link relationship between the clusters is stored and managed in the value of the FAT entry. Therefore, when reading the file data from the beginning to the end, it is necessary to specify the cluster number of the next link destination by referring to the FAT (205, 206) every time the cluster boundary is reached. Similarly, when performing seek processing to read an arbitrary position in the file, refer to FAT (205, 206) and follow the link for the number of clusters corresponding to the seek size to identify the cluster number where the desired data is stored. There is a need to. For this reason, the seek process takes a longer processing time in proportion to the file size. Here, assuming a case where a 1 GB file is managed in units of 16 KB clusters, the number of times the link is traced is about 65000 times, and when a relatively low-speed CPU is used, the seek process may take several seconds. Furthermore, since the FAT (205, 206) holds only the forward link information of the file, when seeking to the front of the file, it is necessary to redo the seek process from the beginning of the file, and the seek cannot be performed at high speed. The problem arises.

Conventionally, as a method for solving such a problem, a method using a jump table has been proposed (see, for example, Patent Document 1). In this method, a list of cluster numbers in which data is stored for each predetermined unit size from the beginning of the file is generated and held as a jump table, and at the seek destination position by referring to the information held in the jump table during seek A technique is disclosed in which the cluster number at the nearest position is found and the seek process is continued with reference to the FAT (205, 206).
JP 2001-236251 A

  However, the above prior art has the following problems. In the conventional method, it takes time to generate a jump table in advance at the time of power activation or the like, which causes a problem that the activation time of the access device becomes long. In addition, information related to the area where the file data is stored is double-managed using FAT (205, 206) and jump table, so when adding or deleting a file, both information can be consistent. Complex processing is required to maintain the state.

  In the present invention, in view of the above problems, an access module, an information recording module, and an information recording system are provided that increase the FAT entry in the FAT file system, thereby speeding up the seek process and preventing inconsistencies in file system management information. The purpose is to provide.

  An access module according to the present invention is an access module for accessing an information recording module including a nonvolatile memory for storing file data, and manages a recording area in the nonvolatile memory in units of fixed-length blocks. Using first entry information including area management information related to the fixed-length block and second entry information including management information of a continuous area composed of a plurality of the fixed-length blocks in the nonvolatile memory, A file system control unit that performs area management of a recording area in the nonvolatile memory is provided.

  The first entry information and the second entry information are managed in a common area management information table existing in the recording area of the nonvolatile memory, and the area management of one fixed-length block is performed. May be performed only in either the first entry information or the second entry information.

  Further, the file system control unit uses the normal FAT processing unit that performs region management using only the first entry information, region management using both the first entry information and the second entry information. It may be configured to include an extended FAT processing unit for performing the above.

  In this configuration, the file system control unit refers to the determination flag stored in the file system management information existing in the recording area in the non-volatile memory, and the normal FAT processing unit and the extended FAT processing unit It can be configured to determine which one to use.

  The first entry information may include information indicating a position of the fixed-length block in which data subsequent to the data stored in the corresponding fixed-length block is stored.

  The second entry information includes information for identifying the first entry information and the second entry information, information indicating a size of a continuous area managed by the second entry information, and , Information indicating a position of the fixed-length block in which data subsequent to data stored in a continuous area managed by the second entry information is stored may be included.

  Further, the file system control unit manages the area using the second entry information when the area for storing file data is an area composed of a predetermined number or more of the fixed-length blocks, When the area for storing data is an area composed of the fixed-length blocks less than the predetermined number, the area may be managed using the first entry information.

  The file system control unit holds current reference position information which is the position of the fixed-length block currently referenced in the file, and changes the current reference position information to an arbitrary position in the file. When performing a seek process, if the current reference position is managed by the first entry information, the current reference position is advanced by the size of one fixed-length block, and the current reference position is the second entry. When managed by information, the current reference position may be advanced by the size of the continuous area managed by the second entry information.

  The information recording module of the present invention is an information recording module including a nonvolatile memory for storing file data, the nonvolatile memory being managed in units of fixed-length blocks, and area management relating to one fixed-length block The area management information of the nonvolatile memory configured by first entry information including information and second entry information including management information of a continuous area composed of a plurality of the fixed-length blocks is stored in the nonvolatile memory. It is characterized by being stored in.

  The information recording system of the present invention comprises an information recording module having a nonvolatile memory for storing file data and an access device for accessing the information recording module, and the nonvolatile memory is managed in units of fixed-length blocks. The non-volatile configuration configured by first entry information including area management information related to one fixed-length block and second entry information including management information of a continuous area composed of a plurality of fixed-length blocks. Memory area management information is stored in the nonvolatile memory, and the access module includes a file system control unit that performs area management of a recording area in the nonvolatile memory using the area management information. And

  According to the present invention, when data is managed by the FAT file system, seek processing can be performed at high speed, and the possibility of inconsistencies in file system management information can be reduced.

  Hereinafter, an access module, an information recording module, and an information recording system of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram of an access module and an information recording module in the embodiment of the present invention. In FIG. 1, the access module 1 includes a CPU 11, a RAM 12, an information recording module interface 13, and a ROM 14. The ROM 14 stores a program for controlling the access module 1, and this program uses the RAM 12 as a temporary storage area and operates on the CPU 11. The information recording module interface 13 is a connection part between the information recording module 2 and the access module 1 and transmits and receives control signals and data. The ROM 14 further includes an application control unit 101, a file system control unit 102, and an information recording module access unit 105. The application control unit 101 controls the entire access module 1 such as data generation and power control. The file system control unit 102 performs control for managing data as files by the FAT file system. The information recording module access unit 105 receives the size and address together with the data from the file system control unit 102 and records the data of the specified size at a specified position in the recording area of the information recording module 2. Controls transmission / reception of commands and data to / from module 2. The file system control unit 102 further includes a normal FAT processing unit 103 and an extended FAT processing unit 104. The normal FAT processing unit 103 is a processing unit that controls the conventional FAT (205, 206), and is the same as the FAT processing unit existing in the conventional access module. The extended FAT processing unit 104 is a processing unit that controls the extended FAT, which is a feature of the present application, and does not exist in the conventional access module.

  On the other hand, in FIG. 1, the information recording module 2 includes an access module interface 21, a CPU 22, a RAM 23, a ROM 24, and a nonvolatile memory 25. The access module interface 21 is a connection part between the information recording module 2 and the access module 1, and is an interface that transmits and receives control signals and data, like the information recording module interface 13. The ROM 24 stores a program for controlling the information recording module 2, and this program operates on the CPU 22 using the RAM 23 as a temporary storage area. The nonvolatile memory 25 is an area for recording data transmitted from the access module 1, and is managed by the FAT file system. The logical address space in the non-volatile memory 25 stores management information existing in the conventional FAT file system such as the master boot record / partition table 203, the partition boot sector 204, and the root directory entry 207. Files and directories stored in the data area 202 are managed. Further, an extended FAT which is a feature of the present application is stored in an area where a conventional FAT (file allocation table) is stored. In the extended FAT, in addition to the normal FAT entries stored in the conventional FAT, extended FAT entries for managing continuous areas together with a small amount of information are stored.

  The access module 1 of the present embodiment has a function of recording an extended FAT entry that manages a continuous area with a small amount of information in the FAT file system constructed in the nonvolatile memory 25 in the information recording module 2. Further, it has a function of reading and interpreting the extended FAT entry. With the function of accessing these extended FATs, it is possible to speed up the file seek process and reduce the possibility of inconsistencies in file system management information.

  Next, the configuration of the extended FAT file system according to the present invention will be described with reference to FIGS. FIG. 5 is a diagram showing the configuration of the extended FAT file system in the present invention. FIG. 5 differs from FIG. 2 showing the configuration of the conventional FAT file system in that the FAT (205, 206) area is changed to an extended FAT (301, 302) area. In the conventional FAT (205, 206), management information corresponding to one cluster is managed using one FAT entry (normal FAT entry), but in the extended FAT (301, 302) of the present invention, the normal FAT entry In addition, an extended FAT entry for storing a series of continuous area information by combining a plurality of FAT entries is also stored.

  FIG. 6 is a diagram showing the configuration of the extended FAT entry in the present invention. The extended FAT entry normally uses three areas of the FAT entry. In the case of FAT16, since one normal FAT entry is managed by 2 bytes, the extended FAT entry has a size of 6 bytes. In the first 2 bytes of the extended FAT entry, a fixed value indicating that this entry is an extended FAT entry is stored as an extended entry signature (ext_sig). For example, 0xFFFE is used as the extended entry signature.

  The subsequent 2 bytes store the number of consecutive clusters (count) of the area managed by this entry. For example, when an extended FAT entry manages a continuous area consisting of 100 clusters, “0x0064 (100)” is stored in the count.

  The last two bytes store the next link destination cluster number (next) indicating the start cluster number of the area existing next to the area managed by this entry. For example, if the start cluster number of the area existing next to the continuous area managed by the extended FAT entry is 1000, “0x03E8 (1000)” is stored in next.

  As described above, information of one cluster is conventionally managed per one FAT entry, whereas information of one continuous area can be managed per one in the extended FAT entry. Therefore, the larger the size of the continuous area, the larger the continuous area can be managed with a small amount of information, and the number of FAT entries referred to at the time of seek processing can be reduced to speed up the processing. Become.

  Next, in order to clarify the features of the present invention, the processing procedure in the conventional FAT file system and the processing procedure in the extended FAT processing unit of the present invention will be compared and described.

First, the file data write processing procedure in the conventional FAT file system will be described with reference to FIG.
(S701) The directory entry 208 of the target file is read.
(S702) The starting cluster number stored in the read directory entry 208 is acquired, and the head position of the file data is confirmed.
(S703) The FAT (205, 206) is read onto the RAM of the access module, the link is traced in the FAT (205, 206) on the RAM in order from the head position of the file data acquired at S702, and the cluster number of the write position is determined. get. The process of following the link here is almost the same as the process of seeking to an arbitrary position in the file, and details will be described later.
(S704) At the time of writing file data, it is determined whether it is necessary to newly allocate a free area to the file. If a free area needs to be allocated, the process proceeds to S705. If it is not necessary to allocate a free area, the process proceeds to S708.
(S705) A free area is searched in the FAT (205, 206) on the RAM, and a free area of one cluster is acquired. Specifically, the FAT entries in the FAT (205, 206) on the RAM are sequentially referred to, a FAT entry whose value is set to 0x0000 is found, and the value of the corresponding cluster number of the FAT entry is obtained. For example, the FAT entry search process may be performed sequentially from the beginning to the end of the FAT (205, 206), or the process is started from the FAT entry next to the FAT entry to which the previous free space is allocated. , 206) may be returned to the beginning of the FAT (205, 206), and the process may be executed up to the FAT entry to which the previous free area is allocated. As described above, the FAT entry search processing procedure is not particularly limited as long as it can realize a process of searching for a free area in the entire FAT (205, 206) area.
(S706) The value of the FAT entry corresponding to the empty cluster number acquired in S705 is set on the RAM to 0xFFFF meaning used.
(S707) The value of the FAT entry corresponding to the cluster number at the current link end is set on the RAM from 0xFFFF to the free cluster number acquired in S705. When it is necessary to acquire a free area, this means appending to the end of the file. In this case, the link is traced to the end of the file in the process of tracing the link in S703. Therefore, the value of the FAT entry corresponding to the current cluster number of the link end is set to 0xFFFF meaning the link end. Therefore, by connecting the link to the free cluster newly acquired in S705 by the processing in S707, the file link becomes longer by one cluster, and it becomes possible to add file data.
(S708) The file data is written into the cluster at the currently referenced write position. If it is determined in S704 that the free area needs to be acquired, the currently referred writing position is the free cluster acquired in S705. If it is determined in S704 that it is not necessary to acquire a free area, the currently referenced write position is a cluster that has arrived as a result of following the link in S703.
(S709) It is determined whether writing of all file data is completed. If file data still remains, the process returns to S704. When writing of all file data is completed, the process proceeds to S710.
(S710) Information such as the file size and the last update date and time stored in the directory entry 208 is updated, and the directory entry 208 stored in the nonvolatile memory of the information recording module is overwritten.
(S711) The FAT (205, 206) stored in the nonvolatile memory of the information recording module is overwritten with the data of the FAT (205, 206) on the RAM of the access module, and the processing is completed.

  By this file data writing process, FILE1. When 10,000 bytes of data are added to TXT, the file changes to a file having 70000 bytes of data as shown in FIG. That is, a cluster with cluster number 6 is acquired as an empty cluster, file data is added, and cluster number 6 is connected to a link on the conventional FAT (205, 206). As a result, FILE1. The TXT link is updated from a state of 4 clusters with cluster numbers 2 to 5 to a state of 5 clusters with cluster numbers 2 to 6.

  Next, a file data write processing procedure in the extended FAT processing unit 104 of the present invention will be described. The access module 1 of the present invention includes a normal FAT processing unit 103 and an extended FAT processing unit 104 in the file system control unit 102. The normal FAT processing unit 103 is a processing unit that accesses the conventional FAT (205, 206), and executes the same procedure as the conventional processing procedure described with reference to FIG. 7 when writing file data. The extended FAT processing unit 104 is a processing unit that interprets and accesses the extended FAT (301, 302) that is a feature of the present invention. In addition, the determination as to which of the normal FAT processing unit 103 and the extended FAT processing unit 104 is used is made by, for example, providing a flag indicating the presence or absence of the extended FAT in the partition boot sector and referring to it. This method is realized. The file data write processing procedure in the extended FAT processing unit 104 of the present invention will be described below using FIG.

(S1001) The directory entry 208 of the target file is read.
(S1002) The start cluster number stored in the read directory entry 208 is acquired, and the head position of the file data is confirmed.
(S1003) The extended FAT (301, 302) is read onto the RAM 12 of the access module 1, and the link is traced in the extended FAT (301, 302) on the RAM 12 in order from the start position of the file data acquired in S1002, and the write position Get the cluster number. The process of following the link here is almost the same as the process of seeking to an arbitrary position in the file, and details will be described later.
(S1004) When writing file data, it is determined whether it is necessary to newly allocate a free area to the file. If it is necessary to allocate a free area, the process proceeds to S1005. If it is not necessary to allocate a free area, the process proceeds to S1011.
(S1005) A free area is searched in the extended FAT (301, 302) on the RAM 12, and a free area of one cluster is acquired. Specifically, the normal FAT entry and the extended FAT entry in the extended FAT (301, 302) on the RAM 12 are sequentially referenced to find the normal FAT entry whose value is set to 0x0000, and the corresponding cluster number of the normal FAT entry Find the value of. The FAT entry search processing procedure is not particularly limited as described with reference to FIG. If an extended FAT entry is found, it is known that an area has already been allocated. Therefore, the normal FAT entries for the number of clusters set in the count of the extended FAT entry are skipped and the search process is performed. continue.
(S1006) It is determined whether the free cluster acquired in S1005 can be managed by the extended FAT entry. If it is determined that management is possible, the process proceeds to S1009. If it is determined that management is not possible, the process proceeds to S1007. The case where management is possible with the extended FAT entry is a case where both of the following two conditions are satisfied.
<Condition 1> The empty cluster acquired in S1005 is a cluster immediately after the cluster at the current link end.
<Condition 2> When the cluster at the current link end is already managed by the extended FAT entry or is managed by the normal FAT entry, there are three or more continuous areas including the free cluster acquired in S1005.
If the above condition is satisfied, the free cluster acquired in S1005 is located at the end of a series of continuous areas and is a continuous area having a size of 3 clusters or more, so entry information for 3 clusters of normal FAT entries. It can be managed by an extended FAT entry composed of
(S1007) When it is determined in S1006 that the extended FAT entry cannot be managed, the value of the normal FAT entry corresponding to the free cluster number acquired in S1005 is set on the RAM 12 to 0xFFFF meaning used.
(S1008) The value of the FAT entry corresponding to the cluster number of the current link end is set on the RAM 12 from 0xFFFF to the free cluster number acquired in S1005. When the current link termination is managed by a normal FAT entry, the value of the free cluster number is set directly in the normal FAT entry. If the extended FAT entry is used for management, the value of the free cluster number is set in the next of the extended FAT entry.
(S1009) When it is determined in S1006 that the extended FAT entry can be managed, the information of the extended FAT entry is updated on the RAM 12. Specifically, when the current link termination is already managed by the extended FAT entry, 1 is added to the value of count in the extended FAT entry. If the current link termination is managed by a normal FAT entry, the head of the continuous area including the free cluster acquired in S1005 is found, and the ext_sig of the extended FAT entry is located at the position of the normal FAT entry corresponding to the head cluster. 0xFFFE is set, and the number of continuous clusters is set in the count of the extended FAT entry, and 0xFFFF which means the link end is set in next.
(S1010) The value of the normal FAT entry corresponding to the free cluster number acquired in S1005 is set on the RAM 12 to 0xFFFF meaning used. However, when the normal FAT entry management is switched to the extended FAT entry management in the processing of S1009, the correct next value is already set in the corresponding area, and thus the processing of S1010 is unnecessary.
(S1011) The file data is written into the cluster at the writing position currently referred to. If it is determined in S1004 that a free area needs to be acquired, the currently referred writing position is the free cluster acquired in S1005. If it is determined in S1004 that it is not necessary to acquire a free area, the currently referenced write position is a cluster that has arrived as a result of following the link in S1003.
(S1012) It is determined whether writing of all file data has been completed. If file data still remains, the process returns to S1004. When writing of all file data is completed, the process proceeds to S1013.
(S1013) Information such as the file size and the last update date and time stored in the directory entry 208 is updated, and the directory entry 208 stored in the nonvolatile memory 25 of the information recording module 2 is overwritten.
(S1014) The extended FAT (301, 302) stored in the nonvolatile memory 25 of the information recording module 2 is overwritten with the data of the extended FAT (301, 302) on the RAM 12 of the access module 1, and the processing is completed. .

  As described above, the main difference between the file data write processing procedure of the present invention and the conventional file data write processing procedure is that the processes described in S1006, S1009, and S1010 are added. The extended FAT control unit 104 of the present invention handles both normal FAT entries and extended FAT entries, and uses both FAT entries depending on whether they can be managed as a continuous area. The handling of this extended FAT entry is very different from the conventional file data write processing procedure, and the seek processing can be speeded up by this extended FAT entry.

Next, in order to compare the seek processing procedure, first, the seek processing procedure in the conventional FAT file system will be described with reference to FIG.
(S1101) The number of seek clusters (SEEK_NUM) is calculated based on the size that is actually moved by seek. The number of seek clusters means the number of clusters that need to follow the link in the seek process. For example, when seeking for 10 clusters from the beginning of the file is performed, “10” is set in SEEK_NUM. When seeking ahead of the current reference position in the file, SEEK_NUM is calculated by calculating the offset from the beginning of the file after the seek operation and converting it to the number of clusters. For example, when the current reference position is present at the 10th cluster position from the beginning of the file and the 2nd cluster seek is performed in front of the file, the position of the 8th cluster from the beginning of the file is the offset after the seek operation, so SEEK_NUM contains “ 8 "is set.
(S1102) The current reference cluster number is confirmed. If seeking from the beginning of the file, the current reference cluster number is the cluster number at the beginning of the file. If the current reference position has already been moved to an arbitrary position in the file by seek processing or read / write processing, the cluster number at that position becomes the current reference cluster number.
(S1103) The FAT (205, 206) read out on the RAM of the access module is referred to, and the value of the FAT entry corresponding to the current reference cluster number is acquired.
(S1104) The FAT entry value (next link destination cluster number) acquired in S1103 is managed as a new current reference cluster number.
(S1105) Since seek processing for one cluster is completed, 1 is subtracted from SEEK_NUM.
(S1106) If the value of SEEK_NUM is other than 0, the process returns to S1102, and the process is continued. When the value of SEEK_NUM is 0, all seek processes are completed, and the process ends.

  That is, in the seek process in the conventional FAT file system, the process of referring to the FAT (205, 206) for each FAT entry and obtaining the cluster number of the next link destination is repeated by repeating the process for the number of seek clusters. become. Therefore, when the number of seek clusters is large, the number of loops becomes enormous and the seek process takes a long time.

Next, a seek process procedure in the extended FAT processing unit 104 of the present invention will be described with reference to FIG.
(S1201) The number of seek clusters (SEEK_NUM) is calculated based on the size that is actually moved by seek. The method for calculating the number of seek clusters is the same as that described with reference to FIG.
(S1202) The current reference cluster number is confirmed. If seeking from the beginning of the file, the current reference cluster number is the cluster number at the beginning of the file. If the current reference position has already been moved to an arbitrary position in the file by seek processing or read / write processing, the cluster number at that position becomes the current reference cluster number.
(S1203) With reference to the extended FAT (301, 302) read out on the RAM 12 of the access module 1, the value of the FAT entry corresponding to the current reference cluster number is acquired. However, if it is already known that the reference cluster number is present in any one of the continuous areas managed by the extended FAT entry after the seek process or the like has already been performed, the extended FAT (301, 302) is newly determined. ) Without proceeding to the next process. In this case, it is assumed that information on the extended FAT entry indicating the continuous area including the current reference cluster number is held in the RAM 12 of the access module 1 when the previous seek process or the like is performed.
(S1204) It is confirmed whether the FAT entry acquired in S1203 is an extended FAT entry. If it is an extended FAT entry, the process proceeds to S1205. If it is not an extended FAT entry, the process proceeds to S1209.
(S1205) When it is determined in the determination process of S1204 that the entry is an extended FAT entry, it is determined whether the seek destination exists within the continuous area indicated by the extended FAT entry acquired in S1203. If it exists in the continuous area, the process proceeds to S1206. If it does not exist in the continuous area, the process proceeds to S1207.
(S1206) If it is determined in S1205 that the seek destination exists in the continuous area, the current reference cluster number is updated to the seek position, and the process ends. For example, it is assumed that the extended FAT entry indicates a continuous area of 10 clusters with cluster numbers 10 to 20, the current reference cluster number is 10, and SEEK_NUM is 5. In this case, since the seek destination exists in the continuous area indicated by the extended FAT entry, 5 of SEEK_NUM is added to 10 of the current reference cluster number, the current reference cluster number is updated to 15, and the process is terminated.
(S1207) When it is determined in S1205 that the seek destination does not exist in the continuous area, the current reference cluster number is updated to the value of the next link destination cluster number (next) of the extended FAT entry. For example, it is assumed that the extended FAT entry indicates a continuous area of 10 clusters with cluster numbers 10 to 20, the next is set to 30, the current reference cluster number is 10, and SEEK_NUM is 15. In this case, since there is no seek destination in the continuous area indicated by the extended FAT entry, the current reference cluster number 10 is updated to 30 which is the value set in the next of the extended FAT entry.
(S1208) Subtract the number of continuous clusters of the extended FAT entry from SEEK_NUM, and proceed to the processing of S1211. For example, it is assumed that the extended FAT entry indicates a continuous area of 10 clusters with cluster numbers 10 to 20, the current reference cluster number is 10, and SEEK_NUM is 15. In this case, the number of continuous area clusters of 10 is subtracted from SEEK_NUM, and SEEK_NUM is set to 5. However, if the current reference cluster number does not indicate the beginning of the continuous area, the number of clusters from the current reference position to the end of the continuous area is subtracted from SEEK_NUM.
(S1209) When it is determined in the determination processing in S1204 that the entry is not an extended FAT entry, the FAT entry value (next link destination cluster number) acquired in S1203 is managed as a new current reference cluster number.
(S1210) Since seek processing for one cluster is completed, 1 is subtracted from SEEK_NUM.
(S1211) When the value of SEEK_NUM is other than 0, the process returns to S1202 and the process is continued. When the value of SEEK_NUM is 0, all seek processes are completed, and the process ends.

  Thus, the main difference between the seek process in the conventional FAT file system and the seek process in the extended FAT processing unit of the present invention is that the processes described in S1204 to S1208 are added. With this processing, when continuous areas are managed together with the extended FAT entry, it is possible to seek the continuous areas together. Specifically, in the prior art, only 1 SEEK_NUM could be subtracted in S1105, but in the method of the present invention, SEEK_NUM can be subtracted collectively for consecutive areas in S1208. This can be reduced, and the seek process can be speeded up.

  Further, this effect will be described with reference to the examples of FIGS. FIG. 13 shows the FILE2. It is a figure which shows an example at the time of managing the file of TXT. Similarly, FIG. 14 is a diagram showing an example when the same file is managed in the extended FAT (301, 302) of the present invention. The file size managed in these two figures, the arrangement of the file data storage area, etc. are the same, and the file data is divided into two continuous areas with cluster numbers 2 to 15 and cluster numbers 24 to 30. A stored example is shown.

  In the conventional seek processing procedure, loop processing always involves referring to FAT (205, 206) of the number of seek clusters regardless of whether the file data is stored in the continuous area. In the example of FIG. 13, when seeking from the beginning to the end of the file, SEEK_NUM is 20, and the number of loops is 20.

  On the other hand, in the seek processing procedure of the extended FAT processing unit 104 of the present invention, when file data is stored in a continuous area, a seek process is collectively performed, and therefore a loop involving reference to the extended FAT (301, 302). It is possible to reduce the number of processing times. In the example of FIG. 14, when seeking from the beginning to the end of the file, SEEK_NUM is 20, but FILE2. Since TXT is composed of two continuous regions, the number of loops is two.

  Since the difference in the number of loops greatly affects the seek processing time, the seek processing is speeded up by the processing of the extended FAT processing unit 104 of the present invention. In the example of the present embodiment, an example in which the FAT (205, 206) or the extended FAT (301, 302) is all read into the RAM 12 of the access module 1 has been described. Is small, only a part of the FAT (205, 206) or the extended FAT (301, 302) can be read onto the RAM 12, and it is necessary to operate while sequentially reading like a cache. In this case, in the worst case, a FAT replacement process occurs every time one loop is processed, and the difference in processing time due to the difference in the number of loops becomes significant, so that the speed-up effect of the present invention becomes more prominent. .

  As described above, the nonvolatile memory 25 of the information recording module 2 of the present invention is managed by the file system, and has extended FAT (301, 302) as area management information. Further, the access module 1 of the present invention refers to the extended FAT (301, 302), and includes an extended FAT processing unit 104 that performs area management by using both the normal FAT entry and the extended FAT entry stored in the extended FAT (301, 302). Including. In the area management in the extended FAT processing unit 104, when file data is stored in a continuous area, an extended FAT entry is used, and the continuous area is managed together with a small amount of information. As a result, the processing time during seeking can be shortened, and the seek process can be speeded up.

  Furthermore, in the extended FAT (301, 302) of the present invention, the area management information is centrally managed by the extended FAT (301, 302). For this reason, the calculation time of the jump table at the time of startup or the like required by the conventional jump table speed-up method is not necessary in the present invention, and the startup time can be shortened. Further, by centrally managing the area management information, it is only necessary to update the information of the extended FAT (301, 302) even when file addition or partial deletion occurs, so it is easy to maintain consistency of the area management information Yes.

  Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. Various modifications can be made without departing from the spirit of the present invention. The numerical values described in the embodiments of the present invention are merely examples, and other values may be used. For example, although the case where 0xFFFE is set to ext_sig of the extended FAT entry has been described, it is only necessary to be able to determine that it is an extended FAT entry, and other methods may be used. Further, the case has been described in which the FAT entry other than the head entry portion is set to 0xFFFF indicating that it has been used in the continuous area managed by the extended FAT entry. This value is not particularly limited, and other values may be used.

  In addition, the case where the extended FAT entry is composed of three fields of ext_sig, count, and next has been described. However, it is sufficient that the continuous area can be managed with less information than conventional FAT entry management. It doesn't matter.

  Further, although an example based on FAT16 in which a FAT entry is composed of 2 bytes has been described, the present invention may be applied to other FAT file systems. In other words, it may be applied to a FAT type file system such as FAT12 or FAT32, and even if the file system is not compatible with the FAT file system, information of one processing unit is stored in one entry as in the FAT. The present invention can be applied to any method that manages areas in association with each other.

  The nonvolatile memory 25 of the information recording module 2 according to the present invention is managed by a file system, and has an extended FAT (301, 302) as area management information. The access module 1 of the present invention includes an extended FAT processing unit 104 that refers to the extended FAT (301, 302) and performs area management. As a result, continuous areas can be managed together in the FAT file system, and seek processing can be speeded up. Such an access module 1 is optimal for devices that handle digital content such as music, still images, and moving images, especially devices that handle content with a large file size, such as PC applications, audio recorders, DVD recorders, HDD recorders, It can be used as a movie, a digital still camera, a mobile phone terminal or the like. Further, the information recording module 2 of the present invention can be used as a removable medium such as a memory card for storing the digital content or the like, or a built-in recording device.

Explanatory drawing which showed the structure of the access module in embodiment of this invention, and an information recording module Explanatory diagram showing the configuration of the FAT file system Explanatory diagram showing the structure of the directory entry Explanatory drawing showing an example of FAT Explanatory drawing which showed the structure of the extended FAT file system in embodiment of this invention Explanatory drawing which showed the structure of the extended FAT entry in embodiment of this invention A flowchart showing file data writing processing in a conventional FAT file system Explanatory drawing which showed an example of the state before file data writing in the conventional FAT file system Explanatory drawing which showed an example of the state after file data writing in the conventional FAT file system The flowchart which showed the file data writing process in embodiment of this invention A flowchart showing a seek process in a conventional FAT file system The flowchart which showed the seek process in embodiment of this invention Explanatory drawing which showed an example of the arrangement state of the file data in the conventional FAT file system Explanatory drawing which showed an example of the arrangement | positioning state of the file data in embodiment of this invention

Explanation of symbols

1 Access Module 2 Information Recording Module 11, 22 CPU
12,23 RAM
13 Information recording module interface 14, 24 ROM
21 Access module interface 25 Non-volatile memory 101 Application control unit 102 File system control unit 103 Normal FAT processing unit 104 Extended FAT processing unit 105 Information recording module access unit 201 File system management information area 202 User data area 203 Master boot record / partition table 204 Partition boot sector 205,206 FAT
207 Root directory entry 208 Directory entry 301,302 Extended FAT

Claims (14)

An access module for accessing an information recording module comprising a nonvolatile memory for storing file data,
Managing the recording area in the nonvolatile memory in units of fixed-length blocks, and first entry information including area management information relating to one fixed-length block;
Second entry information including management information of a continuous area composed of a plurality of the fixed-length blocks in the nonvolatile memory;
An access module comprising a file system control unit for managing a recording area in the nonvolatile memory using The first entry information and the second entry information are managed in a common area management information table existing in a recording area of the nonvolatile memory,
2. The access module according to claim 1, wherein the area management of one fixed-length block is performed only in one of the first entry information and the second entry information. The file system control unit
A normal FAT processing unit that performs area management using only the first entry information;
An extended FAT processing unit that performs area management using both the first entry information and the second entry information;
The access module according to claim 2, further comprising: The file system control unit
A determination flag stored in file system management information existing in a recording area in the non-volatile memory is referred to determine which of the normal FAT processing unit and the extended FAT processing unit to use. The access module according to claim 3. The first entry information is:
3. The access module according to claim 2, further comprising information indicating a position of the fixed-length block in which data subsequent to the data stored in the corresponding fixed-length block is stored. The second entry information is:
Information for identifying the first entry information and the second entry information;
Information indicating the size of the continuous area managed by the second entry information;
3. The access module according to claim 2, further comprising information indicating a position of the fixed-length block in which data subsequent to data stored in a continuous area managed by the second entry information is stored. The file system control unit
When the area for storing file data is an area composed of a predetermined number or more of the fixed-length blocks, the area is managed using the second entry information,
3. The area is managed using the first entry information when an area for storing file data is an area composed of the fixed-length blocks less than the predetermined number. Access module. The file system control unit
Holding the current reference position information, which is the position of the fixed-length block currently referenced in the file,
When performing a seek process for changing the current reference position information to an arbitrary position in the file, if the current reference position is managed by the first entry information, only the size of one fixed-length block is stored. The current reference position is advanced, and when the current reference position is managed by the second entry information, the current reference position is advanced by the size of the continuous area managed by the second entry information. The access module according to claim 2. An information recording module comprising a non-volatile memory for storing file data,
The nonvolatile memory is managed in units of fixed-length blocks,
First entry information including area management information relating to one fixed-length block;
Second entry information including management information of a continuous area composed of a plurality of the fixed-length blocks;
An information recording module, wherein area management information of the non-volatile memory configured as described above is stored in the non-volatile memory. The first entry information and the second entry information are managed in a common area management information table existing in a recording area of the nonvolatile memory,
10. The information recording module according to claim 9, wherein the area management of one fixed-length block is performed only in one of the first entry information and the second entry information. The first entry information is:
11. The information recording module according to claim 10, further comprising information indicating a position of the fixed-length block in which data subsequent to the data stored in the corresponding fixed-length block is stored. The second entry information is:
Information for identifying the first entry information and the second entry information;
Information indicating the size of the continuous area managed by the second entry information;
11. The information recording module according to claim 10, further comprising information indicating a position of the fixed-length block in which data subsequent to data stored in a continuous area managed by the second entry information is stored. An information recording system comprising an information recording module having a nonvolatile memory for storing file data, and an access device for accessing the information recording module,
The nonvolatile memory is managed in units of fixed-length blocks,
First entry information including area management information relating to one fixed-length block;
Second entry information including management information of a continuous area composed of a plurality of the fixed-length blocks;
The non-volatile memory area management information configured by is stored in the non-volatile memory,
The information recording system, wherein the access module includes a file system control unit that performs area management of a recording area in the nonvolatile memory using the area management information. The first entry information and the second entry information are managed in a common area management information table existing in a recording area of the nonvolatile memory,
14. The information recording system according to claim 13, wherein the area management of one fixed-length block is performed only in one of the first entry information and the second entry information.

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