JP2007109181A - Data processor and its control method, computer program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase an access speed to a file system with a hierarchical structure even in a system of a small memory capacity. <P>SOLUTION: Recording positions of entry information of a directory which has once been accessed and of data successful in the directory last are held and, when there is an access request to the same directory, held information is used to control the access. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data processing device, a control method thereof, a computer program, and a storage medium.

  Conventionally, when a file system having a hierarchy (directory) structure is built on a nonvolatile memory and accessed, it is necessary to search the hierarchy sequentially for each access and find the target file by diving in order. In addition, even when accessing another file existing in the same hierarchy, it is necessary to search the hierarchy in order and repeat the same process of diving in order.

  As a method for suppressing the repetition of the hierarchy search, a technique in which information of each hierarchy is made resident on the system has been proposed (see Patent Document 1).

However, this method is not suitable for a system with a small memory capacity because all the information of each layer must be secured in the memory in the system. There is also a problem that the initial operation becomes heavy because all the information in the hierarchy must first be searched.
JP-A-5-324435

  Therefore, an object of the present invention is to make it possible to speed up access to a file system having a hierarchical structure even in a system with a small memory capacity.

  In order to achieve the above object, the present invention provides a data processing apparatus that can be connected to an external device and can be mounted with a nonvolatile storage medium that holds data in a hierarchical structure, and the nonvolatile storage medium from the external device An accepting means for accepting an access request, an extracting means for extracting hierarchical information for specifying an access target included in the access request, and a storage location of data belonging to a predetermined hierarchy in the nonvolatile storage medium Based on the storage means for storing the storage location information, the extracted hierarchical information, and the storage location information, entry information including the storage location to be accessed in the nonvolatile storage medium is stored in the nonvolatile storage medium. Entry information acquisition means acquired from the access information recorded on the nonvolatile storage medium based on the entry information. Access means for accessing the target data, and the entry information acquisition means determines whether or not the first storage location information for the first tier to which the access target belongs is stored in the storage means. When the first determination means and the first determination means determine that the first storage position information is not stored, the storage information is higher than the first hierarchy in the hierarchy information and the storage A search means for searching for a second hierarchy closest to the first hierarchy among the hierarchies in which the storage location information is stored in the means, and when the second hierarchy is searched by the search means, Using the second storage position information of the second hierarchy, the entry information of the third hierarchy belonging to the second hierarchy is acquired, and the third hierarchy of the third hierarchy is acquired based on the acquired entry information. 3 memory locations Writing means for generating and writing information to the storage means, and the searching and writing by the writing means are performed by the first storage position information as the third storage position information in the storage means. The entry information to be accessed is acquired from the non-volatile storage medium based on the first storage position information stored in the storage unit, which is repeated until it is written.

  As described above, according to the present invention, it is possible to speed up access to a file system having a hierarchical structure built on a nonvolatile memory even in a system with a small memory capacity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

  In FIG. 1, reference numeral 1 denotes a data processing device. Reference numeral 2 denotes a removable memory card (nonvolatile memory). 3 is an external device. The data processing device 1 constructs a file system on the memory card 2 and responds to a file access request from the external device 3. The data processing device 1 is configured as a reader / writer device for the memory card 2 and can write and read data to and from the memory card 2. The memory card 2 is a card-like recording medium such as a compact flash (registered trademark) or an SD card, and is detachable from the data processing apparatus 1. The external device 3 may be composed of a general-purpose personal computer, for example, and instructs the data processing device 1 to write or read data.

  Of the internal configuration of the data processing device 1, reference numeral 10 denotes a data processing unit for receiving a file access request from the external device 3 and performing media access to the memory card 2 in accordance with the format of the file system. Reference numeral 11 denotes a bus for transmitting and receiving data among the data processing unit 10, the volatile memory 12 and the connector 13. Reference numeral 12 denotes a volatile memory. The volatile memory 12 has a temporary save area for temporarily saving data (entry information and main body data) on the memory card 2 and a directory information holding area for holding information on the hierarchy (directory) of the file system. . In the directory information holding area, a parent directory information table is held, and the parent directory information is registered according to an LRU (Least Recently Used) algorithm. That is, in the parent directory information table, the registration data is ranked in ascending order of unused time. Reference numeral 13 denotes a connector for transmitting / receiving data to / from the memory card 2 via the bus 11. Reference numeral 14 denotes a connector for transmitting and receiving data between the data processing device 1 and the external device 3. The connector 14 corresponds to USB, IEEE1394, or the like.

  In the present embodiment, the nonvolatile memory is described as the removable memory card 2, but the memory card 2 may be configured as a non-removable nonvolatile memory. Further, the memory card 2 may be configured as an external storage connected by wire / wireless as a nonvolatile memory.

  Next, an example of a file system constructed on the memory card 2 will be described with reference to FIGS. FIG. 13 is a diagram simply showing an example of the data structure on the memory card 2, and FIG. 14 is a diagram showing an example of the data structure of entry information.

  In FIG. 13, reference numeral 1301 denotes a master boot recorder (MBR). 1302 is a boot sector and 1303 is FAT. In the FAT, a table of FAT entries corresponding to all clusters on the memory card 2 is stored. The FAT entry is, for each cluster, a free space (0), the last cluster of the file, or a value indicating where the file is stored next to the cluster.

  Next to the FAT 1303, a root directory is located. In the case of FIG. 13, the root directory stores entry information 1304 to 1306 of file 1, file 2, and directory 1, and includes one empty entry information 1307. Note that FIG. 13 is only an example shown as an example, and more entry information can be stored in the root directory. The entry information is information including a storage position in the memory card 2 which is a nonvolatile storage medium such as a file or directory to be accessed, and details thereof are as shown in FIG. 14 as an example.

  In FIG. 14, 1400 indicates the entire entry information. Reference numeral 1401 denotes an area for storing a data name (file name or directory name). Reference numeral 1402 denotes an area for storing a data extension. Reference numeral 1403 denotes an area for storing data attributes. This attribute includes at least a file, a directory, and a free area. Reference numeral 1404 denotes an area for storing the time when data was created (creation time). Reference numeral 1405 denotes an area for storing the date (creation date) when the data was created. Reference numeral 1406 denotes an area for storing a date when the data was last accessed (last access date). Reference numeral 1407 denotes an area for storing the time (update time) when the data was last updated. Reference numeral 1408 denotes an area for storing the date (update date) when the data was last updated. Reference numeral 1409 denotes an area for storing the number of the first cluster (starting cluster number) among clusters storing data corresponding to the entry information 1400. Reference numeral 1410 denotes an area for storing the size of main body data corresponding to the entry information 1400. The entry information 1400 has a predetermined size (for example, 32 bytes).

  In FIG. 13, the attribute of the entry information 1304 and 1305 is “file”, the attribute of the entry information 1306 is “directory”, and the attribute of the entry information 1307 is “free space”.

  In addition, the start cluster number 1409 of the entry information 1304 for the file 1 stores the leading cluster number of the clusters in which the main data 1308 of the file 1 is stored. Based on the start cluster number 1409, the cluster chain in the FAT 1303, and the data size 1410, the main data 1308 of the file 1 can be accessed.

  Further, the start cluster number 1409 of the entry information 1306 for the directory 1 stores the start cluster number of the entry information of the data included in the directory 1. Based on the start cluster number 1409, the cluster chain in the FAT 1303, and the data size 1410, entry information of all data included in the directory 1 can be accessed. In the case of FIG. 13, the file 3 entry information 1310, the file 4 entry information 1311, the subdirectory 1 entry information 1312, and the subdirectory 2 entry information 1313 are stored as the body data of the directory 1.

  Here, the file 3 and the file 4 can access the main body data 1314 and 1315 in the same manner as the file 1 described above. Similarly to the directory 1, the entry information 1316 and 1317 included in the subdirectory 1 and the subdirectory 2 can be accessed.

  Next, an example of the directory structure of data stored in the memory card 2 corresponding to this embodiment will be described with reference to FIG. In FIG. 15, DIR1000 and DIR2000 directories are stored under the root directory. The DIR 1000 stores DIR1100 and DIR1200 directories, and DIR1100 stores DIR1110 and DIR1120 directories. DIR1110 includes FIL1110A. TXT and FIL1110B. A text file of TXT is stored. On the other hand, DIR1120 includes FIL1120A. TXT and FIL1120B. A text file of TXT is stored.

  The DIR 1200 stores a DIR 1210, and the DIR 1210 stores a DIR 1211 and a DIR 1212, respectively. DIR1211 includes FIL1211A. TXT and FIL1211B. TXT is stored, and DIR1212 has FIL1212A. TXT and FIL1212B. TXT is stored.

  The DIR 2000 stores the DIR 2100, and the DIR 2100 includes the FIL 2100A. From TXT to FIL2100Z. Up to TXT is stored.

  Next, an example of the data structure of the parent directory information table held in the directory information holding area will be described with reference to FIG.

  In FIG. 16, in the parent directory information table 1500, information regarding the storage location of data belonging to a predetermined directory is registered as parent directory information for each directory. The parent directory information includes an LRU 1601, a directory name 1602, a cluster chain 1603, a free entry 1604, and a last access entry 1605.

  The LRU 1601 indicates the newness of the registered parent directory information, and the lower the number, the more recently registered. For example, comparing the parent directory information with the directory name 1602 “/ DIR1000” and the parent directory information with “/ DIR1000 / DIR1100”, it can be seen that “/ DIR1000” is registered in the table 1600 first. In this way, each time a new registration is made, the LRU 1601 is moved up and deleted from the parent directory information table 1600 in order from the oldest one.

  The directory name 1602 registers a full path directory name. For example, when the directory name 1602 is registered for “DIR1110”, “/ DIR1000 / DIR1100 / DIR1110” is registered as a full path. The cluster chain 1603 is a chain of clusters in which the main body data of the directory is recorded, and a combination of the start cluster number 1409 and the cluster chain registered in the FAT 1303 is registered. That is, by using this cluster chain 1603, it is possible to read an entry in the target directory from the memory card 2 without referring to the FAT 1303 of the memory card 2 itself.

  In the empty entry 1604, the number of the first empty entry among the empty entries included in the directory having the directory name 1602 is registered. Since entry information 1400 is stored as 32-byte data, the start position of the first empty entry can be specified by this number. In the last access entry 1605, the number of the entry accessed last in the directory is registered. With this number, the start position of the last access entry can be specified in the same manner as the start position of the empty entry.

  Next, processing in the data processing apparatus 1 corresponding to the embodiment of the present invention will be described.

<Overall processing>
FIG. 2 is a flowchart of a main routine executed in the data processing apparatus 1. First, in step S100, an access request from the external device 3 is accepted. In step S101, it is monitored whether or not an access request is accepted. If an access request is accepted ("YES" in step S101), the process proceeds to step S102. On the other hand, if not accepted (“NO” in step S101), the process returns to step S100.

  Note that the access request accepted in step S100 includes hierarchy information as full path information of the data to be requested. Here, it is assumed that the received request is, for example, a request to read a file “FIL1110A.TXT”. At this time, the position where the file is stored in the memory card 2 is expressed as “/DIR1000/DIR1100/DIR1110/FIL1110A.TXT” in a full path, which is hierarchical information.

  In step S102, it is determined whether the received request is a data read request. If it is a read request (“YES” in step S102), the process proceeds to step S108, and data is read from the memory card 2. On the other hand, if it is not a read request (“NO” in step S102), the process proceeds to step S103.

  In step S103, it is determined whether or not the accepted request is a data write request. If it is a write request (“YES” in step S103), the process proceeds to step S109. In step S109, a process for writing the write data transmitted from the external device 3 to the memory card 2 is performed. On the other hand, if it is not a write request (“NO” in step S103), the process proceeds to step S104.

  In step S104, it is determined whether the received request is a new data creation request. If it is a new creation request (“YES” in step S104), the process proceeds to step S110. In step S110, a new creation process is performed based on a request from the external apparatus 3. On the other hand, if it is not a new creation request (“NO” in step S104), the process proceeds to step S105.

  In step S105, it is determined whether or not the accepted request is a data deletion request. If it is a deletion request (“YES” in step S105), the process proceeds to step S111. In step S111, the deletion request target data is deleted based on the request from the external device 3. On the other hand, if it is not a deletion request (“NO” in step S105), the process proceeds to step S106.

  In step S106, an error is returned to the external device 3 in step S107, assuming that the received request is a request that cannot be handled by the data processing apparatus 1. When the processing from step S108 to step S111 is performed, the processing result is returned to the external device 3 in step S107.

<Read process>
Next, the data reading process in step S108 will be described with reference to FIG. FIG. 3 is a flowchart showing an example of details of a data read process as a subroutine.

  In FIG. 3, in step S200, entry information 1400 of data requested to be read from the external device 3 is acquired. If the entry information 1400 of the data requested to be read does not exist and cannot be acquired (“NO” in step S201), the process proceeds to step S206. In step S206, a notification that the requested data does not exist (non-existence notification) is returned to the caller of this subroutine.

  On the other hand, if the entry information 1400 of the data requested to be read exists and can be acquired (“YES” in step S201), the process proceeds to step S202. In step S <b> 202, based on the acquired entry information 1400, the main data of the requested data is read from the memory card 2 to the volatile memory 12.

  Next, in step S203, it is determined whether or not the data reading in step S202 has been performed normally. This determination can be made based on, for example, whether or not the data size read into the volatile memory 12 matches the data size registered in the data size 1410 in the entry information 1400. If it is determined that the data has been normally read (“YES” in step S203), the process proceeds to step S204. On the other hand, when it is determined that the reading could not be performed normally (“NO” in step S203), the process proceeds to step S205.

  In step S204, the request target data read to the volatile memory 12 and a notification that the requested read process has been successful are returned to the caller of this subroutine. In step S205, an error notification (read error notification) indicating that the requested read cannot be performed normally is returned to the caller of this subroutine.

<Write processing>
Next, the data writing process in step S109 will be described with reference to FIG. FIG. 4 is a flowchart showing an example of details of a data writing process as a subroutine.

  In FIG. 4, in step S300, entry information 1400 of data requested to be written from the external device 3 is acquired. If the entry information 1400 of the data requested to be written does not exist and cannot be acquired (“NO” in step S301), the process proceeds to step S306. In step S306, a notification that the requested data does not exist (non-existence notification) is returned to the caller of this subroutine.

  On the other hand, if the entry information 1400 of the data requested to be written exists and can be acquired (“YES” in step S301), the process proceeds to step S302. In step S302, the data acquired for writing from the external device 3 is written in the media access position of the memory card 2 determined from the entry information 1400. At this time, the contents of the entry information 1400 held in the memory card 2 are also updated.

  Next, in step S303, it is determined whether or not the data writing in step S302 has been performed normally. The determination here is performed depending on, for example, whether the data size registered in the data size 1410 of the entry information 1400 after update by writing matches the size of data acquired for writing from the external device 3. Can do. If it is determined that the writing has been normally performed (“YES” in step S303), the process proceeds to step S304. On the other hand, if it is determined that writing could not be performed normally (“NO” in step S303), the process proceeds to step S305.

  In step S304, a notification that the requested write process has been successful is returned to the caller of this subroutine. In step S305, an error notification (writing error notification) indicating that the requested writing could not be normally performed is returned to the caller of this subroutine.

<New creation process>
Next, new data creation processing in step S110 will be described with reference to FIG. FIG. 5 is a flowchart showing an example of details of a new data creation process as a subroutine.

  In step S400, a free entry is secured on the memory card 2 for the entry information 1400 for data requested to be newly created by the external device 3. Here, the “free entry” is a free area in which the entry information 1400 in the initial state can be stored. The data that is required to be newly created is either a file or a directory. If an empty entry could not be secured (“NO” in step S401), the process proceeds to step S405, and a notification (processing failure notification) indicating that the new creation process related to the request has failed is sent to this subroutine. Return to caller.

  On the other hand, if a free entry can be secured (“YES” in step S401), the process proceeds to step S402 to create initial entry information 1400. Specifically, if the request is for creating a new file, the data size 1410 is generated as 0. If the request is for a new directory, an empty directory is set.

  If the initial entry information 1400 has been successfully created (“YES” in step S403), a notification that the new creation process has been successful is returned to the caller of this subroutine in step S404. On the other hand, if creation of the entry information 1400 in the initial state has failed ("NO" in step S403), the process proceeds to step S405, and a process failure notification is returned to the caller of this subroutine.

<Delete processing>
Next, the data deletion processing in step S111 will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the details of the data deletion process as a subroutine.

  6, in step S500, entry information 1400 of data (file or directory) requested to be deleted from the external device 3 is acquired from the memory card 2. If the entry information 1400 of the data requested to be deleted does not exist and cannot be acquired (“NO” in step S501), the process proceeds to step S508, and the data related to the request is transmitted to the external device 3. Notification of non-existence (non-existence notification) is performed.

  On the other hand, if the entry information 1400 of the data requested to be deleted exists and can be acquired (“YES” in step S501), the process proceeds to step S502. In step S502, the main data of the data related to the deletion request is deleted from the memory card 2. In step S503, the corresponding entry information held in the memory card 2 is changed to an empty state. This change can be made by changing the value of the attribute 1403 in the entry information 1400 to a value indicating “free state”. If the target of the deletion request is a directory, the parent directory information of the directory registered in the parent directory information table 1600 of the volatile memory 12 is also deleted in step S504.

  When the processing from step S502 to step S504 is completed normally ("YES" in step S505), the process proceeds to step S506, and a notification that the deletion process has succeeded (deletion process success notification) is issued. Return to the caller of the subroutine. On the other hand, if the process did not end normally ("NO" in step S505), the process proceeds to step S507, and a notification that the deletion process has failed (deletion process failure notification) is sent to the caller of this subroutine. return.

<Entry Information 1400 Acquisition Process>
Next, the acquisition process of the entry information 1400 corresponding to this embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing an example of a subroutine for the process of acquiring entry information 1400 corresponding to the present embodiment. The entry information 1400 acquisition process is performed in step S200 in FIG. 3, step S300 in FIG. 4, and step S500 in FIG.

  In FIG. 7, in step S600, the parent directory information is acquired from the parent directory information table 1600 for the parent directory of the request target data based on the hierarchical information included in the request from the external device 3. Specifically, if the request target data is the file “FIL1110A.TXT” in the directory “/ DIR1000 / DIR1100 / DIR1110”, the parent directory is “DIR1110”. If the parent directory information cannot be acquired (“NO” in step S601), the process proceeds to step S605. In step S605, a notification (non-existence notification) that the entry information 1400 of the requested data does not exist is returned to the caller of this subroutine.

  On the other hand, when the parent directory information can be acquired (“YES” in step S601), the process proceeds to step S602. In step S602, based on the parent directory information, the data in the directory is read to the temporary save area, and the entry information 1400 of the request target data is searched. If the entry information 1400 is found as a result of the search (“YES” in step S603), the entry information 1400 is returned to the caller of this subroutine in step S604. On the other hand, if the entry information 1400 does not exist (“NO” in step S603), a non-existence notification is returned to the caller of this subroutine in step S605.

<Search processing of entry information 1400>
Next, the entry information 1400 search process will be described with reference to FIG. FIG. 8 is a flowchart of the processing subroutine. The search process for the entry information 1400 is performed in step S602 in FIG. 7 and step S1006 in FIG.

  First, in step S700, data in the vicinity of the last access entry 1605 (for example, two entries before and after) of the data included in the parent directory information is read into the temporary save area of the volatile memory 12 and searched. If entry information 1400 of the target file (FIL1110A.TXT in the above example) is found as a result of this search (“YES” in step S701), the process proceeds to step S702. In step S702, the entry information 1400 is returned to the caller of this subroutine. At this time, based on the target entry information 1400, the final access entry 1605 of the parent directory information in the parent directory information table 1600 is updated. Thereby, the entry information 1400 found in step S701 becomes a new final access entry 1605.

  On the other hand, when the entry information 1400 cannot be found (“NO” in step S701), the process proceeds to step S703. Even when the last access entry 1605 is not registered, the process proceeds to step S703. In step S703, based on the parent directory information, all entry information 1400 in the parent directory is read into the temporary save area of the volatile memory 12 and searched. If the target entry information 1400 can be found (“YES” in step S704), the entry information 1400 is returned to the caller of this subroutine in step S702. Further, the last access entry 1605 of the parent directory information is updated based on the target entry information 1400. If the empty entry 1604 is not registered, the empty entry 1604 is updated based on the result of all entry scanning in step S703. On the other hand, if all the entry information cannot be found by searching (“NO” in step S704), a notification that the corresponding entry information 1400 does not exist (non-existence notification) is returned to the caller of this subroutine in step S705. .

<Process for securing free entry>
Next, a process for securing a free entry will be described with reference to FIG. FIG. 9 is a flowchart of the processing subroutine. The processing for securing the free entry is performed in step S400 in FIG.

  9, in step S800, parent directory information is acquired from the parent directory information table 1600 based on the hierarchy information included in the request from the external device 3. If the parent directory information cannot be acquired (“NO” in step S801), the process proceeds to step S809. In step S809, the caller of this subroutine is notified that a free entry cannot be secured (allocation failure notification).

  On the other hand, if the parent directory information can be acquired (“YES” in step S801), the process proceeds to step S802, and the parent directory is scanned to search for a free entry. If an empty entry is found (“YES” in step S803), the empty entry is returned to the caller of this subroutine in step S804.

  On the other hand, if no empty entry is found (“NO” in step S803), the process proceeds to step S806. In step S806, the parent directory area on the memory card 2 is expanded. If the parent directory area can be expanded (“YES” in S806), the directory is scanned in step S807 to search for a free entry again. The empty entry found here is returned to the caller of this subroutine in step S804.

  On the other hand, if the parent directory area cannot be expanded (“NO” in step S806), the process proceeds to step S808. In step S808, a notification that the expansion of the parent directory has failed and a free entry cannot be secured (expansion failure notification) is returned to the caller of this subroutine.

<Free entry search processing>
Next, the empty entry search process will be described with reference to FIG. FIG. 10 is a flowchart of the processing subroutine. This empty entry search process is performed in steps S802 and S807 of FIG.

  In FIG. 10, in step S900, based on the empty entry 1604 of the parent directory information table 1600, an empty entry in the parent directory is searched.

  If the empty entry 1604 is registered (“YES” in step S901), the empty entry is returned to the caller of this subroutine in step S902. On the other hand, if the empty entry 1604 is not registered (“NO” in step S901), a notification that there is no empty entry (empty entry non-existence notification) is returned to the caller of this subroutine in step S903.

<Parent directory information acquisition processing>
Next, an example of processing for acquiring parent directory information will be described with reference to FIG. FIG. 11 is a flowchart showing an example of a subroutine for acquiring parent directory information. This parent directory information acquisition process is performed in step S600 of FIG.

  In FIG. 11, in step S1000, it is checked whether or not corresponding parent directory information is held in the parent directory information table 1600.

  At this time, N is the number of hierarchies to which the target directory belongs. For example, if “DIR1110” of “/ DIR1000 / DIR1100 / DIR1110 /” is a directory from which parent directory information is to be acquired, the number of layers N is “3”. The number N of hierarchies is counted as “1” for a directory immediately under the root directory.

  In step S1001, the parent directory information table 1600 is searched for a directory (“DIR1110” in the above example) of the N (“3” in the above example) hierarchy from which parent directory information is to be obtained. If the target parent directory information is held (“YES” in step S1001), the process proceeds to step S1002. In step S1002, the registration order of the table is changed so that the LRU 1601 of the parent directory information is minimized. Thereby, the unused time of the parent directory information is set to the shortest. In addition, it is possible to reduce the time for the next search for whether or not the parent directory information is held for the same parent directory. In step S1003, the acquired parent directory information is returned to the caller of this subroutine.

  On the other hand, if the parent directory information of the N-th layer directory is not registered in the table 1600 (“NO” in step S1001), the process proceeds to step S1004. In step S1004, it is determined whether or not the number N of hierarchies is one. When N is 1 (“YES” in step S1004), the process proceeds to step S1010. On the other hand, when N is not 1 (“NO” in step S1004), the process proceeds to step S1005.

  In step S1005, the process of “acquire parent directory information” shown in FIG. 11 is executed for the directory (“DIR1100” in the above example) on the N-1 (“2” in the above example) hierarchy. In this way, the parent directory information acquisition process for the upper directory is recursively executed.

  In step S1005, when the parent directory information of the N-1 upper hierarchy can be acquired (“YES” in step S1006), the process proceeds to step S1007. In step S1007, based on the acquired parent directory information, the entry information 1400 in the directory (“DIR1100” in the above example) is read into the temporary save area of the volatile memory 12. Then, the entry information 1400 of the directory (“DIR1110” in the above example) of the N (“3” in the above example) hierarchy is searched. As a result, when the entry information 1400 can be acquired for the N-th directory (“YES” in step S1008), the process proceeds to step S1009. In step S1009, based on the entry information 1400, the parent directory information is registered in the parent directory information table 1600. Thereafter, the process proceeds to step S1003, and the acquired parent directory information is returned to the caller of this subroutine.

  If the parent directory information of the N-1 (“2” in the above example) hierarchy cannot be acquired in step S1005, and if the entry information 1400 is not present in step S1008, the process proceeds to step S1012.

  If it is determined in step S1004 that N = 1, parent directory information is not registered in the table 1600 for the directory in the first layer (“DIR1000” in the above example), that is, the directory directly under the root. In that case, the entry information 1400 is read from the root directory of the memory card 2, and the entry information 1400 of the directory in the first hierarchy is searched. If the entry information 1400 has been acquired (“YES” in step S1011), the process proceeds to step S1009. In step S1009, based on the entry information 1400, the parent directory information for the first level directory is registered in the table 1600. On the other hand, if the entry information 1400 could not be acquired, the process proceeds to step S1012 and a notification that there is no parent directory information (non-existence notification) is returned to the caller of this subroutine.

<Parent directory information registration process>
Next, an example of processing for registering parent directory information in the table 1600 will be described with reference to FIG. FIG. 12 is a flowchart showing an example of a subroutine of processing for registering parent directory information. This registration process of the parent directory information is performed in step S1009 of FIG.

  In FIG. 12, in step S1100, it is checked whether the parent directory information table 1600 on the volatile memory 12 has a vacancy. If the table 1600 is empty (“YES” in step S1101), the process proceeds to step S1102, and the parent directory information is registered in the table 1600 based on the acquired entry information 1400. At this time, the newly registered parent directory information has a minimum LRU 1601, that is, “1”, and the LRU 1601 of other parent directory information is incremented one by one.

  On the other hand, if there is no free space in the table 1600 (“NO” in step S1101), the process proceeds to step S1103, and the parent directory information having the maximum LRU 1601 is deleted from the table 1600. Thereafter, in step S1102, the minimum LRU 1601 is allocated and registered in the newly registered parent directory information, and the LRU 1601 of the other parent directory information is moved up one by one.

<Specific example of parent directory information acquisition>
Hereinafter, the parent directory information acquisition process in FIG. 11 will be described more specifically.

<Specific example 1>
In the data structure of FIG. 15, / DIR1000 / DIR1100 / DIR1110 / FIL1110A. Consider the case of reading TXT. At this time, it is assumed that no parent directory information is registered in the parent directory information table 1600. The registration status of the parent directory information table 1600 is shown in FIG. In FIG. 17, only the LRU 1601 and the directory name 1602 are shown for simplicity. FIG. 17A shows an unregistered parent directory information table 1600.

  First, in step S1000, it is searched whether the parent directory information of the directory “DIR1110” is held in the parent directory information table 1600. This search can be performed based on whether or not there is parent directory information whose directory name 1602 is “/ DIR1000 / DIR1100 / DIR1110” corresponding to the full path.

  Since parent directory information is not registered in the parent directory information table 1600, it is naturally determined in step S1001 that there is no parent directory information. Therefore, the process proceeds to step S1004, and it is determined whether or not the number of hierarchies N of the directory from which the parent directory information is to be obtained is 1. Since the DIR 1110 corresponds to the third hierarchy with the DIR 1000 directly under the root directory as the first hierarchy, the number of hierarchies: N is 3, and is not 1. Therefore, the process proceeds to step S1005.

  In step S1005, parent directory information acquisition processing is performed for the directory on the (N-1) th layer, that is, the directory on the first layer. Here, the directory of the Nth layer is DIR1110, and its parent directory DIR1100 is the directory of the (N-1) th layer.

  The parent directory information acquisition process in step S1005 is a process of executing the entire process of FIG. 11 using the DIR 1100 as a directory on the Nth layer. Similarly, when steps S1000, S1001, and S1004 are executed for the DIR 1100, the parent directory information table 1600 is in an unregistered state and N is not 1, so the process reaches step S1005. Here, parent directory information acquisition processing is executed for “DIR1000”, which is one level higher than “DIR1100”.

  “DIR1000” is processed in the same way up to step S1001, but “DIR1000” is a directory immediately under the root directory, and therefore the number of hierarchies: N is one. Therefore, the process proceeds from step S1004 to step S1010. In step S1010, the entry information 1400 in the root directory of the memory card 2 is read into the temporary save area of the volatile memory 12, and the entry information 1400 of the DIR 1000 is searched. If the entry information 1400 of the DIR 1000 is found here, the process proceeds to step S1009 and the parent directory information is registered in the parent directory information table 1600 (FIG. 17B). In step S1003, the parent directory information of “DIR1000” is returned to the caller of the parent directory information acquisition routine of “DIR1000”.

  The calling source is step S1005 in the parent directory information acquisition routine of “DIR1100”. When the parent directory information of “DIR1000” is acquired in step S1005 (“YES” in step S1006), the process proceeds to step S1007. In step S1007, based on the parent directory information of “DIR1000”, the entry information 1400 in “DIR1000” is read into the temporary save area of the volatile memory 12, and the entry information 1400 of “DIR1100” is searched.

  If entry information 1400 of “DIR1100” is found (“YES” in step S1008), the process proceeds to step S1009. In step S1009, based on the entry information 1400, the parent directory information “DIR1100” is registered in the parent directory information table 1600 (FIG. 17C). At this time, the previously registered parent directory information of “DIR1000” is changed to a value older than the parent directory information of “DIR1100” because the value of LRU 1601 is changed.

  In step S1003, the parent directory information of “DIR1100” is returned to the caller of the parent directory information acquisition routine of “DIR1100”. The calling source here is step S1005 in the parent directory information acquisition routine of “DIR1110”. When the parent directory information of “DIR1100” is acquired in step S1005 (“YES” in step S1006), the process proceeds to step S1007. In step S1007, based on the parent directory information of “DIR1100”, the entry information 1400 in “DIR1100” is read into the temporary save area of the volatile memory 12, and the entry information 1400 of “DIR1110” is searched.

  If entry information 1400 of “DIR1110” is found (“YES” in step S1008), the process proceeds to step S1009. In step S1009, based on the entry information 1400, the parent directory information of “DIR1110” is registered in the parent directory information table 1600 (FIG. 17D). At this time, the previously registered parent directory information of “DIR1000” and “DIR1100” is changed to a value older than the parent directory information of “DIR1110” because the value of LRU 1601 is changed.

  In step S1003, the parent directory information of “DIR1100” is returned to the caller of the parent directory information acquisition routine of “DIR1100”. The calling source here is, for example, step S600 in the entry information 1400 acquisition routine of FIG.

  Note that “FIL1110A.TXT” will be further described, for example, when reading. In FIG. 7, based on the parent directory information of “DIR1110”, the entry information 1400 in “DIR1110” can be searched to obtain the entry information 1400 of “FIL1110A.TXT”. The entry information 1400 of “FIL1110A.TXT” obtained here is returned to the reading process of FIG. 3, which is the caller of the entry information acquisition process of FIG. In the reading process of FIG. 3, the main body data of “FIL1110A.TXT” can be read based on the obtained entry information 1400 in step S202.

  As described above, even when no parent directory information is stored in the parent directory information table 1600, the target parent directory information is obtained by recursively executing the processing of FIG. 11, and the target file data is stored. Can be acquired. Here, the parent directory information is registered in the table 1600 based on the entry information 1400 obtained in the course of executing the recursive process. As a result, as in <Specific Example 2> shown below, the target parent directory information can be efficiently acquired without going back to the root directory.

<Specific example 2>
A case will be described in which files stored in other directories are read using the directory search history or the like in <Specific Example 1>. For example, consider the case of reading “/DIR1000/DIR1200/DIR1210/DIR1211/FIL1211A.TXT”. Here, the parent directory information of “DIR1200”, “DIR1210”, and “DIR1211” is not held in the parent directory information table 1600 (FIG. 18A). However, since “DIR1000” is held in the parent directory information table 1600 in the above <Specific example 1>, the parent directory information can be acquired without having to access the memory card 2. According to the parent directory information of “DIR1000”, the parent directory information of “DIR1200”, “DIR1210”, and “DIR1211” can be acquired in the same manner as in <Specific example 1> (FIGS. 18B and 18C). (D)).

  By registering the acquired parent directory information in the parent directory information table 1600, the old parent directory information registered before that is deleted from the table 1600. For example, in FIG. 18C, the parent directory information whose LRU 1601 is “8” is deleted from the table 1600 when the parent directory information of the DIR 1211 is registered.

  Further, based on the acquired parent directory information of “DIR1211”, the entry information 1400 of “FIL1211A.TXT” can be acquired in the same manner as described above, and the main data of the target file can be finally acquired.

  As described above, when the parent directory information of any directory in the full path of the target file is registered in the parent directory information table 1600, the target file can be efficiently obtained using this. it can.

  As described above, according to the present embodiment, the entry information of the accessed directory can be used when data is read from, written to, newly created, or deleted from a memory card as a removable storage medium. it can. Therefore, it is not necessary to reserve all the information of each layer in the memory in advance, and even a system with a small memory capacity can efficiently access the memory card.

  Further, the data to be accessed can be searched using the position where the last accessed data is recorded in the same directory. This makes it possible to reach the target data at a higher speed than accessing all data in the directory in order.

[Other Embodiments]
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.

  The object of the present invention can also be achieved by supplying a storage medium storing software program codes for realizing the above-described functions to the system, and the system reading and executing the program codes. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. In addition, an operating system (OS) running on a computer performs part or all of actual processing based on an instruction of the program code, and the above-described functions are realized by the processing.

  Furthermore, you may implement | achieve with the following forms. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Then, based on the instruction of the program code, the case where the above-described functions are realized by the CPU included in the function expansion card or the function expansion unit performing part or all of the actual processing is also included.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

It is a figure which shows an example of a structure of the data processing system corresponding to embodiment of this invention. It is a flowchart which shows an example of the whole process in the data processor 1 corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the read-out process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the write processing corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the new creation process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the deletion process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the acquisition process of the entry information corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the entry information search process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the process of the empty entry ensuring corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the empty entry search process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the parent directory information acquisition process corresponding to embodiment of this invention. It is a flowchart which shows an example of the subroutine of the process which hold | maintains the directory information corresponding to embodiment of this invention. It is a figure which shows simply an example of the data structure in the memory card 2 corresponding to embodiment of this invention. It is a figure which shows an example of the data structure of the entry information corresponding to embodiment of this invention. It is a figure which shows an example of the directory structure of the data stored in the memory card 2 corresponding to embodiment of this invention. It is a figure which shows an example of the data structure of the parent directory information table corresponding to embodiment of this invention. It is a figure which shows an example of the registration state of the parent directory information table corresponding to embodiment of this invention. It is a figure which shows another example of the registration state of the parent directory information table corresponding to embodiment of this invention.

Claims (16)

A data processing device that can be connected to an external device and can be loaded with a nonvolatile storage medium that holds data in a hierarchical structure,
Accepting means for accepting an access request to the nonvolatile storage medium from the external device;
Extraction means for extracting hierarchical information for specifying an access target included in the access request;
In the non-volatile storage medium, storage means for storing storage position information related to storage positions of data belonging to a predetermined hierarchy;
Entry information acquisition means for acquiring, from the nonvolatile storage medium, entry information including the storage position to be accessed in the nonvolatile storage medium based on the extracted hierarchical information and the storage position information;
Access means for accessing the access target data recorded in the nonvolatile storage medium based on the entry information;
The entry information acquisition means includes
First determination means for determining whether or not first storage position information for a first hierarchy to which the access target belongs is stored in the storage means;
When it is determined by the first determination means that the first storage position information is not stored, the storage position information is higher than the first hierarchy in the hierarchy information and the storage means stores the storage position information. Search means for searching for a second hierarchy closest to the first hierarchy among the stored hierarchies;
When the second hierarchy is searched by the search means, the entry information of the third hierarchy belonging to the second hierarchy is acquired using the second storage position information of the second hierarchy. And writing means for generating third storage position information of the third hierarchy based on the acquired entry information and writing to the storage means,
The processing in the searching means and the writing means is repeated until the first storage position information is written in the storage means as the third storage position information,
The data processing apparatus, wherein the entry information to be accessed is acquired from the nonvolatile storage medium based on the first storage position information stored in the storage means. In the search means, when the second hierarchy cannot be searched,
The writing means obtains entry information of a hierarchy that belongs immediately below the root directory in the hierarchy information from data stored in a root directory of the nonvolatile storage medium, and the third information is based on the entry information. The data processing apparatus according to claim 1, wherein the storage position information is generated.   The storage location information specifies the location information where the entry information of the data belonging to the predetermined hierarchy is recorded in the nonvolatile storage medium, and the entry information used last among the entry information The data processing apparatus according to claim 1, further comprising:   The writing means, when acquiring the entry information of the third hierarchy, based on information for specifying the last used entry information included in the second storage location information, Search the periphery of the entry information corresponding to the information, and search for all the entry information acquired based on the second storage position information when the periphery does not include the entry information of the third hierarchy The data processing apparatus according to claim 3, wherein the data processing apparatus performs the processing. The storage position information further includes information on a position where writing of new entry information can be started,
The access request includes at least one of data reading, writing, new creation and deletion, and when the access request is a data new creation request,
The entry information acquisition means secures an area where entry information can be newly created based on the first storage position information and information on a position where writing of the new entry information can be started,
5. The data processing apparatus according to claim 3, wherein the access unit creates entry information in an initial state in the area. In the storage means, a predetermined number of the storage position information is stored in an order assigned in the order in which the writing means uses or writes the information.
2. The writing unit according to claim 1, wherein when the predetermined number is exceeded by new writing, the writing unit deletes the old storage position information and performs the new writing. The data processing device according to any one of 5.   When the first determination unit determines that the first storage position information is stored, the first storage position information is assigned an order given to the newest storage position information. The data processing apparatus according to claim 6, characterized in that: A non-volatile storage medium that can be connected to an external device and that holds data in a hierarchical structure can be mounted, and the non-volatile storage medium includes data that includes a storage unit that stores storage location information regarding the storage location of data belonging to a predetermined hierarchy A method for controlling a processing apparatus, comprising:
An accepting step of accepting an access request to the nonvolatile storage medium from the external device;
An extraction step for extracting hierarchical information for specifying an access target included in the access request;
An entry information acquisition step for acquiring, from the nonvolatile storage medium, entry information including the storage position to be accessed in the nonvolatile storage medium based on the extracted hierarchical information and the storage position information;
An access step of accessing the access target data recorded in the nonvolatile storage medium based on the entry information;
In the entry information acquisition step,
A first determination step of determining whether or not first storage position information about a first hierarchy to which the access target belongs is stored in the storage unit;
When it is determined that the first storage position information is not stored in the first determination step, the storage position information is higher in the hierarchy information than the first hierarchy and the storage unit stores the storage position information. A search step of searching for a second layer closest to the first layer among the stored layers;
When the second hierarchy is searched in the search step, the entry information of the third hierarchy belonging to the second hierarchy is acquired using the second storage position information of the second hierarchy And generating a third storage position information of the third hierarchy based on the acquired entry information, and writing to the storage unit,
The processing in the search step and the writing step is repeated until the first storage position information is written in the storage unit as the third storage position information.
A control method for a data processing apparatus, wherein the entry information to be accessed is acquired from the nonvolatile storage medium based on the first storage position information stored in the storage unit. In the search step, when the second hierarchy cannot be searched,
In the writing step, from the data stored in the root directory of the non-volatile storage medium, entry information of a hierarchy that belongs immediately below the root directory in the hierarchy information is acquired, and the third information is obtained based on the entry information. 9. The method of controlling a data processing apparatus according to claim 8, wherein the storage location information is generated.   The storage location information specifies the location information where the entry information of the data belonging to the predetermined hierarchy is recorded in the nonvolatile storage medium, and the entry information used last among the entry information 10. The method for controlling a data processing apparatus according to claim 8 or 9, wherein information for the data processing is included.   In the writing step, when acquiring the entry information of the third hierarchy, based on information for specifying the last used entry information included in the second storage location information, Search the periphery of the entry information corresponding to the information, and search for all the entry information acquired based on the second storage position information when the periphery does not include the entry information of the third hierarchy The method for controlling a data processing apparatus according to claim 10, wherein the method is performed. The storage position information further includes information on a position where writing of new entry information can be started,
The access request includes at least one of data reading, writing, new creation and deletion, and when the access request is a data new creation request,
In the entry information acquisition step, based on the first storage position information and information on a position where writing of the new entry information can be started, an area where entry information can be newly created is secured,
12. The method according to claim 10, wherein in the access step, entry information in an initial state is created in the area. In the storage unit, a predetermined number of the storage position information is stored in an order assigned in the order in which the use or the writing is performed in the writing step,
9. The writing step according to claim 8, wherein when the predetermined number is exceeded by new writing, the old storage position information is deleted and the new writing is performed. 12. A method for controlling a data processing apparatus according to any one of claims 12 to 13.   In the first determination step, when it is determined that the first storage position information is stored, the first storage position information is assigned an order given to the newest storage position information. The method of controlling a data processing apparatus according to claim 13, wherein:   A computer program for causing a computer to execute the control method of the data processing device according to claim 8.   A computer-readable storage medium storing the computer program according to claim 15.

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