JP4026352B2 - Navigation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention also relates to navigation equipment to be read out the file data stored in the hard disk.
[0002]
[Prior art]
In the case of a format compliant with MS-DOS (registered trademark of Microsoft Corporation), the file stored on the hard disk is stored in units of an area of about several kilobytes called a cluster. This cluster is an aggregate of sectors which are the minimum recording units. When a file is stored in the hard disk immediately after the logical format is performed, the arrangement of clusters related to the file is continuous. Multiple files are usually stored on the hard disk, but if a part of the data for each file is deleted or a part of it is modified and newly written, the cluster placement for that file Is discontinuous.
[0003]
The hard disk is a table that stores the addresses of clusters that make up each file in a chain so that file data stored in a discontinuous arrangement of clusters can be read without any trouble. A certain FAT (File Allocation Table) area is formed.
[0004]
Here, FIG. 6 conceptually shows an example of the logical layout of the formatted hard disk. In the reserved area, a BPB (BIOS Parameter Block) indicating various information related to the manufacturer name, version number, and format of the hard disk is written. Following the reserved area, the FAT area and a FAT area that is a copy of the FAT (Preliminary) is arranged. Following the FAT area (spare), there is a root directory area indicating the head address of the cluster that constitutes each file, followed by a file area in which file data in units of clusters is stored.
[0005]
FIG. 7 shows an example of the correspondence between the root directory, FAT, and file data. The root directory stores information such as the address (start address) of the start cluster constituting the files A, B, and C, and other file capacities. For example, the start address of the file A is 0002H, and when the file area address 0002H is accessed, the file A-1 that is the start cluster of the file A can be read.
[0006]
The address of the start cluster is also a FAT index (entry). When the 0002H of the FAT entry is referred to, the next cluster address 0003H forming the file A is written therein, and the address of the file area When accessing 0003H, the next cluster file A-2 can be read. Since the next cluster address 0007H is written in the FAT entry 0003H, the next cluster file A-3 can be read by accessing the file area address 0007H.
[0007]
In this way, even when a cluster of one file is arranged in a state where addresses are discontinuous in the file area, each cluster can be traced by referring to the FAT (in this example, the FAT entry) FFFFH indicates a file end). Therefore, for example, when a file data read request is generated as a result of the operation of the application program, the OS (operating system) or the driver software of the hard disk driver sequentially reads the cluster of the file while referring to the FAT area. Yes.
[0008]
[Problems to be solved by the invention]
However, since the OS and the like sequentially read the file clusters while referring to the FAT one by one, regardless of the actual arrangement state of the plurality of clusters constituting a file, the time required for reading the file data becomes long. There was a problem that.
[0009]
The present invention has been made in view of the above circumstances, an object thereof is to provide a Luna navigation equipment can be made shorter reading time of the file data.
[0010]
[Means for Solving the Problems]
According to the navigation device of the first aspect, when there is a request for reading file data on the hard disk, the data reading means first refers to the information table , and the information about the file has the address of each unit area “continuous”. If this is the case, the access address is determined based on the start address of the file and data is read out. On the other hand, when the information indicates that the address is “discontinuous”, the data reading means determines the access address based on the head address and, if necessary, by referring to the chain address table on the hard disk. Read data.
[0011]
In other words, if the address arrangement of each unit area constituting a file is discontinuous, the address for accessing a part of data located in the middle of the file is traced by referring to the chained address table one by one. Without it you can't decide. On the other hand, when the address arrangement of each unit area is continuous, it is possible to determine the access address without referring to the chain address table.
[0012]
Therefore, if it is found in advance that the address of each unit area is continuous by referring to the information table , the data reading means only adds the relative address (offset) from the file start address if it is known. Thus, the access address can be easily determined and the data can be read out, and there is no need to refer to the chain address table one by one. Therefore, it is possible to greatly shorten the time for reading the necessary file data from the hard disk. In addition, the navigation device of the present invention creates an information table in the initial setting process when the battery power supply is turned on and started.
[0013]
According to the navigation device of the second aspect, when there is a request for reading file data on the hard disk, the data reading means first refers to the information table, and if there is continuous information regarding the portion related to the access target of the file, An access address is determined based on the continuous information, and an access address is determined by referring to the chain address table for a portion where no continuous information exists.
[0014]
That is, when the addresses of a plurality of unit areas forming a file are partially continuous, the continuous information is stored in the information table in a format such as how many unit areas are continuous from a certain address. . Therefore, the data reading means can determine the access address without referring to the chained address table for the portion where the unit area address is continuous for the file, thereby reducing the time for reading the file data. Can do. In addition, the navigation device of the present invention creates an information table in the initial setting process when the battery power supply is turned on and started.
[0015]
According to the navigation apparatus of the third aspect, the data reading means reads the contents of the head address table from the hard disk and stores them in the storage means. That is, a hard disk generally has a table in which the head addresses of unit areas constituting each file are arranged together with a chain address table. Therefore, if the contents of the head address table are also stored in the storage means in advance, the data reading means does not need to access the hard disk to obtain the head address of the file to be read. Can be further shortened.
[0016]
According to the navigation device of the fourth aspect, when the data reading means refers to the information table in response to the file data read request and information on the file is not stored, the data reading means accesses the hard disk table. Information based on the read contents is stored in the information table . According to this configuration, the data reading unit does not need to perform processing for storing necessary information in the information table independently, and a file data read request is issued for the operation in claims 1 to 3. Therefore, when the information table is referred to, necessary information can be stored in the information table according to the reference result.
[0017]
According to the navigation device of the fifth aspect, the file data stored in the hard disk is used as map data used for navigation. That is, generally, map data used for navigation is often provided in a state of being recorded on a recording medium such as a CD-ROM or a DVD-ROM. Assuming that the map data is provided in a state stored in the hard disk, the hard disk is built in the device together with the hardware of the driver. Therefore, it is necessary for the user to be aware of handling such a recording medium. Disappears. Moreover, the capacity of hard disks has been remarkably increased in recent years, and those having a capacity of about several tens of Gbytes have been put into practical use. Therefore, even map data having a large capacity corresponding to a wide area can be stored in a lump, and there is an advantage that there is no need to replace the recording medium according to the area.
[0018]
In that case, the unit area address of the map data file stored in the dedicated hard disk is in a continuous state in advance, and in addition, the map data file is frequently partially rewritten while being used for navigation. Therefore, the state where the unit area addresses are continuous is constantly maintained. Therefore, if the present invention is applied, map data can be read from the hard disk at extremely high speed .
Can do.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a vehicle navigation apparatus will be described with reference to FIGS. FIG. 2 is a functional block diagram showing an electrical configuration of the vehicle navigation device. The vehicle navigation device 1 includes a GPS receiver 2, a vehicle speed sensor 3, a direction sensor 4, an operation switch 5, a navigation ECU (Electronic Control Unit) 6 connected to these, a display device 7 connected to the navigation ECU 6, and a hard disk A unit 8 is provided.
[0020]
The navigation ECU (file data reading device) 6 is constituted by a microcomputer, and includes a well-known CPU (data reading means, computer) 9, ROM (recording medium) 10, RAM (storage means) 11, An I / O (not shown) and a bus line for connecting them are provided.
[0021]
The GPS receiver 2 detects the absolute position of the vehicle based on a radio signal transmitted from a GPS (Grobal Positioning System) satellite, and the vehicle speed sensor 3 and the direction sensor 4 detect the relative position of the vehicle. It is. Since these configurations 2 to 4 each have an error based on a unique property, each output result is configured to be used while being interpolated. Depending on the required accuracy, some of these may be used, or a geomagnetic sensor, a vehicle steering sensor, or the like may be further added.
[0022]
The hard disk unit (driver) 8 is a device for inputting various data including so-called map matching data and map data for improving the position detection accuracy. At the stage of shipping the vehicle navigation device 1, the hard disk unit 8D. Already contains map data. The map data includes road data related to roads and other data such as place names, topography, and buildings. The navigation ECU 6 transfers data to and from the hard disk unit 8 via an interface such as ATA (AT Attachment).
[0023]
On the screen of the display device 7, the vehicle current position mark, the map data input from the hard disk unit 8, and additional data such as a guide route to be displayed on the map and a mark of a set point are superimposed and displayed. It has become. The operation switch 5 is composed of, for example, a touch switch or a mechanical switch arranged integrally with the display device 7, and is used for various inputs. When the destination position is input by the operation switch 5, the navigation ECU 6 automatically selects the optimum route from the current position of the vehicle to the destination to calculate the guidance route, The route guidance information is displayed on the display device 7.
[0024]
FIG. 3 shows an image of a program stored in the ROM 10 inside the navigation ECU 6. The ROM 10 stores an OS 12 and an application program 13 for car navigation that operates on the OS 12. The OS 12 includes a file system (computer program) 14 for managing data transfer to and from the hard disk unit 8, an ATA driver 15 for executing data transfer based on the ATA interface, and map data on the display device 7. The graphic system 16 for performing graphic display based on the above is provided. These programs are read out and executed directly by the CPU 9 or once transferred to a predetermined area of the RAM 11 for execution.
[0025]
FIG. 4 is an image showing an example of the information table 11T stored in the RAM 11. The information table 11T has areas in which a file name, a head address of the file on the hard disk, and a continuous flag are written. FIG. 4 shows a state in which these pieces of information have already been written. In the initial state, the data in these areas are cleared to all “0”, for example. The RAM 11 may be either SRAM or DRAM as long as the stored contents are backed up by a battery power supply even when the ignition switch of the vehicle is OFF.
[0026]
Next, the operation of this embodiment will be described with reference to FIGS. FIG. 1 is a flowchart showing the processing contents when the CPU 9 of the navigation ECU 6 operates mainly in accordance with the file system 14 of the OS 12. When the CPU 9 first performs necessary initial settings when the power is turned on (step S1), the CPU 9 waits until a file read request based on the operation of the application program 13 is generated (step S2).
[0027]
That is, in the navigation for vehicles, the position of the vehicle changes as the vehicle travels, so the map data of the area corresponding to the current position of the vehicle is partially extracted from the wide-area map data stored in the hard disk 8D. Is frequently read and displayed on the display device 7. Here, for example, a file read request is accompanied by a read command such as File_read with a file name: map data, a relative address indicating a read start address in the file: 100H, a read size: 2 Mbytes, and the like. .
[0028]
When there is a file read request (step S2, "YES"), the CPU 9 refers to the information table 11T in the RAM 11 (step S3). If the information table 11T is cleared and no information is stored ("NO"), the CPU 9 accesses the hard disk unit 8 and the root directory (the top of the hard disk 8D shown in FIG. 5A). Reference is made to (address table) 17 (step S7). When the start cluster address: X000H of the map data is acquired, the file name: map data and the head address: X000H are written and stored in the information table 11T of the RAM 11 (step S8). The above address notation is merely an example, and the number of digits does not reflect the actual data size or the like.
[0029]
Next, the CPU 9 refers to the FAT (chain address table) 18 of the hard disk 8D shown in FIG. 5B (step S9). As a result, if it is determined that all the addresses of the clusters (unit areas) 19 constituting the map data are connected (step S10, “YES”), “1” is set in the storage area of the continuous flag in the information table 11T of the RAM 11. Write and set (step S11). At this time, the information in the information table 11T regarding the map data is in the state shown in FIG.
[0030]
In this case, the map data is read based on the head address (step S12). That is, since the addresses of the clusters 19 are continuous, in order to read 2 Mbytes from the relative address 100H of the map data, it is only necessary to read 2 Mbytes starting from the cluster address X100H on the hard disk 8D. Then, the process returns to step S2 and waits until the next file read request is generated.
[0031]
On the other hand, as a result of referring to the FAT 18 in step S9, if the CPU 9 determines in step S10 that the cluster addresses constituting the file are discontinuous (“NO”), the CPU 9 performs the contents of the FAT 18 for each cluster 19 as usual. The file data is read while following (Step S13). Then, the process returns to step S2. In this case, the continuous flag of the information table 11T remains reset in the initial state for the file.
[0032]
As described above, after the information on the route directory 17 and the FAT 18 relating to the map data is written in the information table 11T, a map data read request is generated again in step S2, and the CPU 9 refers to the information table 11T in step S3. In the subsequent step S4, “YES” is determined as “there is information”, and the process proceeds to step S5.
[0033]
In step S5, the CPU 9 determines whether or not the continuous flag of the information table 11T related to the map data is set. If it is set (“YES”), the CPU 9 performs the step based on the head address stored in the information table 11T. Map data is read out in the same manner as in S12 (step S6). That is, in this case, the CPU 9 does not need to access the hard disk 8D in order to obtain address information for reading file data, and can determine an access address simply by referring to the information table 11T of the RAM 11.
[0034]
As a result of referring to the information table 11T in step S3, if the continuous flag of the file to be read is reset, the CPU 9 determines “NO” in step S5, and proceeds to step S13. In this case, as described above, the file data is read while tracing the contents of the FAT 18 for each cluster 19 as described above.
[0035]
As described above, according to the present embodiment, when there is a read request for file data on the hard disk 8D, the CPU 9 refers to the RAM 11 and the continuous flag is set in the information table 11T, and each of the clusters 19 constituting the file. When the address is “continuous”, the access address is determined based on the start address of the file, data is read, the continuous flag is reset, and the address of each cluster 19 is “discontinuous” Is based on the top address and reads the data by determining the access address by referring to the FAT 18 on the hard disk 8D as necessary.
[0036]
That is, when the addresses of the clusters 19 constituting the file are continuous, the CPU 9 can easily determine the access address without referring to the FAT 18 one by one by referring to the information table 11T. Therefore, the time for the CPU 9 to read out the necessary file data from the hard disk 8D can be greatly shortened.
[0037]
In addition, since the CPU 9 reads the contents of the root directory 17 from the hard disk 8D and stores it in the RAM 11, it is not necessary to access the hard disk 8D to obtain the head address of the file to be read. It can be shortened.
[0038]
Then, when the CPU 9 refers to the information table 11T in response to a file data read request and information on the file is not stored, the CPU 9 accesses the root directory 17 and the FAT 18 of the hard disk 8D and reads the content. Since the information is stored in the information table 11T, there is no need to perform processing for storing the information independently, and according to the result of referring to the information table 11T when the file data read request is issued, Information can be stored if necessary.
[0039]
Furthermore, according to the present embodiment, the map data is stored in the hard disk 8D of the hard disk unit 8 which constitutes a part of the navigation device 1, and is used for navigation. That is, assuming that the map data is provided in a state stored in the hard disk 8D, the hard disk 8D is built in the navigation device 1 as the hard disk unit 8 together with the hardware of the driver. It is no longer necessary to be conscious of handling various recording media. Further, large-capacity hard disk 8D can collectively store large-capacity map data corresponding to a wide area, and there is no need to change the recording medium according to the area.
[0040]
In this case, the cluster address of the map data file stored in the dedicated hard disk 8D is in a continuous state as shown in FIG. 5B, and there is almost no sector defect. In addition, since the map data file is not frequently rewritten in a state where it is used for navigation, a state in which cluster addresses are continuous is constantly maintained. Therefore, if the present invention is applied, map data can be read from the hard disk 8D at extremely high speed.
[0041]
After that, as a result of using the hard disk 8D for a long time, a part of the sector is defective, or the version of the map data is upgraded and the part is deleted and rewritten. Even when the cluster address of the data file becomes discontinuous, data can be read as usual.
[0042]
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following modifications or expansions are possible.
Only the continuous flag corresponding to the file name may be stored in the information table 11T, and the address of the start cluster 19 of the file may be read from the root directory 17 every time.
Not only when all the cluster addresses are continuous for one file, but when some cluster addresses are continuous, the information table 11T has continuous information regarding the partial continuous state. May be. For example, information is stored in a format such as how many clusters from a certain address are continuous. Then, as a result of referring to the information table 11T, the CPU 9 determines the access address without referring to the FAT 18 for the portion where the cluster address is continuous, as in the above embodiment, and the FAT 18 for the other portion as usual. To read the file data. Even in such a configuration, the file data read time can be shortened.
[0043]
The processing in steps S7 to S11 may be performed in advance in the initial setting in step S1.
The OS 12 including the file system 14 is not limited to the one stored in the ROM 10 in advance, but is provided in a state stored in a recording medium such as a CD-ROM, and the ROM (in this case, for example, an EEPROM or the like) is provided from the recording medium. A rewritable ROM) may be loaded.
The hard disk unit is not limited to the one used in the vehicle navigation apparatus 1 but may be one connected to a personal computer or the like. Therefore, the file data to be stored in the hard disk is not limited to map data, and any file data can be used as long as it is handled by, for example, a personal computer and generally stored in the hard disk.
The chained address table is not limited to FAT, and the head address table is not limited to the root directory. Even if these names differ due to different hard disk formats, apply if they have substantially the same function. Can do.
Needless to say, the data may be program data.
[Brief description of the drawings]
FIG. 1 is an example of a case where the present invention is applied to a vehicle navigation apparatus, and a flowchart showing processing contents when a CPU of a navigation ECU mainly operates according to an OS file system. FIG. 3 is a functional block diagram showing the electrical configuration of the navigation device. FIG. 3 is a diagram showing an image of a program stored in a ROM inside the navigation ECU. FIG. 4 is a diagram showing an example of an information table stored in the RAM. 5A and 5B are diagrams showing an image of a storage state of a hard disk, where FIG. 6A is a root directory area, FIG. 5B is a FAT area, and FIG. 5C is a file area. FIG. FIG. 7 is a diagram conceptually showing an example of a logical layout of a formatted hard disk. FIG. 7 is a diagram corresponding to FIG.
1 is a vehicle navigation device, 6 is a navigation ECU (file data reading device), 8 is a hard disk unit, 8D is a hard disk, 9 is a CPU (data reading means, computer), 10 is a ROM (recording medium), 11 is a RAM (RAM) Storage means), 11T is an information table, 12 is an operating system, 14 is a file system (computer program), 17 is a root directory (head address table), 18 is FAT (chain address table), and 19 is a cluster (unit area). Show.

Claims (5)

A file is divided and stored for each unit area, and a hard disk storing a chain address table in which an address indicating the chain of the unit area for each file is stored is accessed in response to a file data read request. In a navigation device comprising data reading means for reading the data,
The data reading means generates an information table including at least a file name and information indicating whether addresses of a plurality of unit areas constituting each file are continuous based on the contents of the chain address table. Storage means for storing,
When the battery power is turned on , the data reading means creates the information table in an initial setting process. When there is a request for reading file data, the data reading means refers to the information table. If it indicates “continuous”, the access address is determined based on the head address of the file, and if the information about the file indicates “discontinuous” of the address, it is based on the head address and, if necessary, the chain. A navigation apparatus, wherein an access address is determined by referring to an address table to read data. A file is divided and stored for each unit area, and a hard disk storing a chain address table in which an address indicating the chain of the unit area for each file is stored is accessed in response to a file data read request. In a navigation device comprising data reading means for reading the data,
It said data reading means, based on the content of the chain address tables, information table including at least a file name, and its continuous information If the address of a plurality of unit regions constituting each file are contiguous for at least a portion Storage means for generating and storing
The data reading means creates the information table in an initial setting process when the battery power is turned on and refers to the information table when there is a request to read file data, and relates to a portion related to the access target of the file When the continuous information exists, an access address is determined based on the continuous information, and when the continuous information does not exist for the part to be accessed of the file, the access address is referred to by referring to the chain address table A navigation device characterized in that data is read out by determining the data. The hard disk stores a head address table in which head addresses of unit areas constituting each file are arranged,
3. The navigation apparatus according to claim 1, wherein the data reading unit reads the contents of the head address table and stores the contents in the storage unit. The data reading means refers to the information table in response to a file data read request, and if information on the file is not stored, information based on the content read by accessing the hard disk table is read. 4. The navigation device according to claim 1, wherein the navigation device is stored in an information table . 5. The navigation apparatus according to claim 1, wherein the file data stored in the hard disk is map data used for navigation .

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