JP2006309581A - Navigation system, cache memory and cache management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load applied to an arithmetic device, and to reduce a time necessary for writing and reading of cache data. <P>SOLUTION: This navigation system has: a cache memory sectionalized into a plurality of section areas having different cache sizes; and a recording processing means deciding an attribute of the cache data, and recording the cache data in the selected section area among the respective section areas on the basis of a decision result. Even if the cache data in a prescribed section area are erased, it is not necessary to rearrange the section areas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a navigation system, a cache memory, and a cache management method.

  Conventionally, in a navigation device, for example, a current position of a vehicle, that is, a current position, is detected by GPS (Global Positioning System), and a rotation angular velocity of a vehicle detected by a gyro sensor, that is, based on a turning angle, The direction of the vehicle, that is, the vehicle direction is detected, map data is read from the data recording unit, a map screen is formed on the display unit, and the vehicle position indicating the current location is displayed on the map screen. A map of the surrounding area and the direction of the vehicle are displayed. Therefore, the driver who is an operator can drive the vehicle according to the own vehicle position displayed on the map screen, the map around the own vehicle position, and the own vehicle direction.

  Further, when the driver inputs a destination and sets search conditions, a route from the departure point to the destination represented by the current location is searched based on the search conditions. The searched route, that is, the searched route is displayed together with the vehicle position on the map screen. Therefore, the driver can drive the vehicle along the displayed search route.

  By the way, the navigation device is provided with a navigation processing unit and the data recording unit, and the CPU as the arithmetic unit of the navigation processing unit reads the traffic information recorded in the data recording unit, and based on the traffic information, a belt-like shape The traffic jam zone is formed and displayed on the map screen.

  However, since the traffic information is recorded on the hard disk in the data recording unit, for example, when the current location changes as the vehicle travels, the traffic information of the next area is read out from the hard disk. The processing time for the process becomes longer, and the load applied to the CPU increases accordingly.

  Therefore, the CPU records a predetermined amount of traffic information as cache data in a cache memory built in the CPU, and reads the cache data from the cache memory when displaying the traffic jam zone (for example, , See Patent Document 1).

  FIG. 2 is a conceptual diagram showing an example of a conventional cache memory.

  In the figure, AR1 is a cache management area, AR2 is a recording area, a plurality of cache areas mi (i = 1, 2,..., X) are set in the recording area AR2, and cache data is recorded in each cache area mi. Is done. n is an empty area where no cache data is recorded.

  In the cache management area AR1, management data representing the position in the recording area AR2 is recorded for each cache area mi. The management data includes a cache head address that represents the head address of the recording area AR2, and an offset value from the cache head address of each cache area mi.

  In the cache memory configured as described above, when the CPU reads the traffic information from the data recording unit, the CPU sequentially sets the cache area mi in the recording area AR2, and writes the traffic information as cache data in the set cache area mi. Therefore, when trying to display a traffic jam zone, the cache data can be read from the cache memory, converted into the traffic jam zone, and displayed. In this case, since the cache memory is used for writing and reading, the processing time can be shortened and the load applied to the CPU can be reduced.

By the way, the cache data is variable data. For example, in the case of traffic information, the amount of data, that is, the data size changes depending on the number of road links included in the area. The memory capacity required for the area mi, that is, the cache size is different. Therefore, as shown in the figure, each cache area mi is set with a different cache size.
JP 2003-330623 A

  However, in the conventional cache memory, since each cache area mi is set close to the cache head address side, the management of the cache area mi becomes extremely complicated. For example, when the predetermined traffic information becomes unnecessary after a lapse of time, the cache data in a predetermined cache area of the cache area mi, for example, the cache area m3 is deleted. Therefore, the CPU rearranges the cache area mi and packs the cache areas m1, m2, m4,... Mx other than the cache area m3 toward the cache head address side. Therefore, the load applied to the CPU increases.

  Also, each time the cache area mi is rearranged, the addresses of a considerable number of cache areas are changed, so that it becomes difficult to specify addresses when writing or reading cache data. In addition, the time required for reading becomes long.

  Therefore, it is conceivable to uniformly set the cache size so that the cache data having the assumed maximum data size among the cache data can be recorded.

  FIG. 3 is a conceptual diagram showing another example of a conventional cache memory.

  In the figure, AR1 is a cache management area, AR3 is a recording area, a plurality of cache areas kj (j = 1, 2,..., Y) are preset in the recording area AR3, and cache data is stored in each cache area kj. To be recorded. In this case, each cache area kj is set with the same cache size.

  In the cache management area AR1, management data representing the position in the recording area AR3 is recorded for each cache area kj. The management data is composed of a cache head address representing the head address of the recording area AR3 and an offset value from the cache head address of each cache area kj.

  In the cache memory configured as described above, the CPU writes the traffic information as cache data in the cache area kj set in advance in the recording area AR3 each time the traffic information of a predetermined area is read.

  In this case, since the cache areas kj are not set so as to be directed toward the cache head address, management of the cache area kj is facilitated. For example, even if the predetermined traffic information becomes unnecessary after a lapse of time and the cache data in the predetermined cache area, for example, the cache area k3 in the cache area kj is deleted, the cache area kj is rearranged. The cache area k3 is made a free area. Therefore, the load applied to the CPU can be reduced.

  Further, since the cache area kj is not rearranged, there is no need to change the address. Therefore, it becomes easy to specify an address when writing or reading necessary cache data, and the time required for writing and reading can be shortened.

  However, in the cache memory having the above-described configuration, the cache size of each cache area kj is increased, so the number of cache areas kj is reduced and the convenience of the cache memory is reduced. Further, since each cache data is recorded in the predetermined cache area kj even when the data size is small, the use efficiency of the cache memory is lowered.

  The present invention solves the problems of the conventional cache memory, reduces the load applied to the arithmetic unit, shortens the time required for writing and reading the cache data, and improves the convenience of the cache memory. An object of the present invention is to provide a navigation system, a cache memory, and a cache management method that can improve the performance and increase the use efficiency.

  Therefore, in the navigation system of the present invention, the cache memory partitioned into a plurality of partition areas having different cache sizes and the attribute of the cache data are determined, and the selected partition area is selected based on the determination result. Recording processing means for recording the cache data in the partitioned area.

  According to the present invention, since the cache memory is partitioned into a plurality of partition areas having different cache sizes, it is not necessary to rearrange the partition areas even if the cache data of a predetermined partition area is erased. Therefore, the load applied to the arithmetic device can be reduced.

  Further, since the rearrangement of the partition area is not performed, it is not necessary to change the address. Therefore, it becomes easy to specify an address when writing or reading necessary cache data, and the time required for writing and reading can be shortened.

  Further, since the recording area is partitioned into partition areas having different cache sizes, the number of cache areas can be increased, and the convenience of the cache memory can be improved.

  Since the cache data is recorded in an appropriate partition area among the respective partition areas depending on the attribute, it is possible to increase the use efficiency of the cache memory.

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

  FIG. 1 is a block diagram showing a navigation system according to an embodiment of the present invention.

  In the figure, 14 is an information terminal, for example, a navigation device as an in-vehicle device mounted on a vehicle, 43 is a network, 51 is an information center as an information provider, and the navigation device 14, network 43, information center 51, etc. The navigation system is configured by the above.

  The navigation device 14 includes a GPS sensor 15 as a current location detection unit for detecting a current location, a data recording unit 16 as an information recording unit in which various information is recorded in addition to map data, and navigation based on the input information. A navigation processing unit 17 that performs various arithmetic processing such as processing, a direction sensor 18 that serves as a direction detection unit that detects the vehicle direction, and a first input for performing predetermined input when operated by a driver as an operator. An operation unit 34 as an input unit, various displays by an image displayed on a screen (not shown), a display unit 35 as a first output unit for notifying the driver, and a predetermined input by voice A voice input unit 36 as a second input unit, a voice output unit 3 as a second output unit for performing various displays by voice and notifying the driver , And a communication unit 38 as a transmission / reception unit functioning as a communication terminal. The navigation processing unit 17 includes a GPS sensor 15, a data recording unit 16, an orientation sensor 18, an operation unit 34, a display unit 35, a voice input unit 36, An audio output unit 37 and a communication unit 38 are connected. The navigation processing unit 17 is connected to a vehicle speed sensor 41 as a vehicle speed detection unit that detects a vehicle speed.

  The GPS sensor 15 detects the current location on the earth by receiving radio waves generated by an artificial satellite, and also detects the time. In the present embodiment, the GPS sensor 15 is used as the current position detection unit, but a distance sensor, a steering sensor, an altimeter, etc. (not shown) are used alone or in combination instead of the GPS sensor 15. You can also Further, a gyro sensor, a geomagnetic sensor, or the like can be used as the direction sensor 18.

  The data recording unit 16 includes a map database including map data files, and map data is recorded in the map database. The map data includes intersection data related to intersections, node data related to nodes, road data related to road links, search data processed for searching, facility data related to facilities, and the like. The data recording unit 16 also records data for outputting predetermined information by the audio output unit 37.

  Further, the data recording unit 16 includes a statistical database composed of statistical data files, a travel history database composed of travel history data files, and the like. Statistical data is stored in the statistical data file, and travel history data is stored in the travel history data file. However, both are recorded as performance data.

  The statistical data is a history of traffic information provided in the past, that is, history information representing a history, and a road traffic information center (not shown) such as a VICS (registered trademark: Vehicle Information and Communication System) center as an information provider. Traffic information provided in the past by the Ministry of Land, Infrastructure, Transport and Tourism, data representing traffic volume by road traffic census (hereinafter referred to as “road traffic census information”), road timetable information, and information center 51 It is created by using probe data, which is travel history data collected from a vehicle (own vehicle or other vehicle), alone or in combination, and processing and statistical processing as necessary. In the statistical data, it is possible to add traffic jam prediction information for predicting a traffic jam status to the history information. In that case, in creating the statistical data, detailed conditions such as date and time, day of the week, weather, various events, seasons, facility information (presence / absence of large facilities such as department stores and supermarkets) are added to the history information.

  The data items of the statistical data include a route on which the vehicle has traveled in the past, that is, link number data (ID) for each road link that constitutes each travel route, a direction flag that represents the travel direction, and information that represents the type of information. Type, congestion degree at each predetermined timing, link required time indicating the required time at each predetermined timing when traveling on each road link, average data for each day of the link required time (for example, day of the week) Average data).

  In addition, the travel history data is calculated and accumulated based on the travel record of the vehicle, that is, data (travel data) representing the travel record on the travel route. The data items of the travel history data include a link required time at each predetermined timing when traveling on each road link, a traffic congestion level at each predetermined timing when traveling on each road link, and the like.

  In the present embodiment, the degree of traffic jam represents the level of traffic jam, and is represented separately for traffic jam, congestion, and non-car jam.

  The data recording unit 16 includes a disk (not shown) such as a hard disk, a CD, a DVD, and an optical disk in order to record the various data, and also reads / writes for reading and writing various data. A head (not shown) such as a head is provided. A memory card or the like can be used for the data recording unit 16.

  The navigation processing unit 17 is a control device that performs overall control of the navigation device 14 and a CPU 31 as an arithmetic device, a RAM 32 that is used as a working memory when the CPU 31 performs various arithmetic processes, Used for recording various programs, various data, programs, etc., as well as programs for the purpose, search for routes to destinations, guidance of searched routes, that is, various programs for performing route guidance, etc. A flash memory (not shown).

  In the present embodiment, various programs can be recorded in the ROM 33 and various data can be recorded in the data recording unit 16, but programs, data, and the like can also be recorded on a disk. In this case, the program, data, etc. can be read from the disk and written to the flash memory. Therefore, the program, data, etc. can be updated by exchanging the disk. When the navigation device 14 is connected to an automatic transmission control device (not shown) mounted on the vehicle for controlling the automatic transmission, a program, data, etc. for controlling the automatic transmission control device Can also be recorded on the disc. Further, the program, data, and the like can be received via the communication unit 38 and written into the flash memory of the navigation processing unit 17.

  The operation unit 34 is operated by the driver to correct the current location at the start of traveling, to input a departure point and a destination, to input a passing point, and to activate the communication unit 38. As the operation unit 34, a keyboard, a mouse, or the like disposed independently of the display unit 35 can be used. Further, as the operation unit 34, a predetermined input operation is performed by touching or clicking an image operation unit such as various keys, switches, and buttons displayed as images on the screen formed in the display unit 35. It is possible to use a touch panel that can be used.

  A display is used as the display unit 35. Then, on various screens formed on the display unit 35, the vehicle position indicating the current location, a map, a searched route, guidance information along the searched route, traffic information, etc. are displayed, or until the next intersection in the searched route. In addition to displaying the distance and the direction of travel at the next intersection, it also displays operation guidance, operation menus, key guidance for the image operation unit, operation unit 34, voice input unit 36, etc. Broadcast programs can be displayed.

  The voice input unit 36 includes a microphone (not shown) and the like, and can input necessary information by voice. Further, the voice output unit 37 includes a voice synthesizer and a speaker (not shown), and the search route, guidance information, traffic information, and the like are output from the voice output unit 37, for example, as voice synthesized by the voice synthesizer. .

  The communication unit 38 transmits various information such as current traffic information and general information transmitted from the road traffic information center to radio wave beacons via radio wave beacon devices, optical beacon devices and the like arranged along the road. , A beacon receiver for receiving as an optical beacon and the like, a radio receiver for receiving a radio broadcast such as FM multiplex broadcast via a radio station, and the like. The traffic information includes traffic jam information, regulation information, parking lot information, traffic accident information, service area congestion status information, and the like, and general information includes news, weather forecasts, and the like. Further, the beacon receiver and the FM receiver are unitized and arranged as a VICS receiver, but can be arranged separately.

  The traffic information specifies an information type indicating a type of information, a mesh number for specifying a mesh composed of a predetermined area, a road link connecting two points (for example, intersections), and / Link number that represents the type of down, and link information that represents the content of information provided corresponding to the link number. For example, when the traffic information is traffic jam information, the link information is the starting point of the road link The congestion start position that represents the distance from the beginning of the congestion to the beginning of the congestion, the degree of congestion, the congestion length that represents the distance of the congestion section from the beginning of the congestion to the end of the congestion, and the link duration that represents the time required to travel on the road link Etc.

  The communication unit 38 can also receive various information such as traffic information and general information from the information center 51. For this purpose, the information center 51 includes a server 53, a communication unit 57 connected to the server 53, a database (DB) 58 as an information recording unit, and the like. A CPU 54, a RAM 55, a ROM 56, etc. are provided as devices. The database 58 records data similar to the various data recorded in the data recording unit 16, for example, the map data, statistical data, travel history data, and the like. Furthermore, the information center 51 can provide travel history data collected from a plurality of vehicles (own vehicle or other vehicle) in real time.

  In the present embodiment, the data recording unit 16 is provided with the map database, statistical database, travel history database, and the like. However, in the information center 51, the map database, statistical database, travel history, etc. A history database or the like can also be provided.

  The navigation system, the navigation processing unit 17, the CPUs 31, 54, the server 53, and the like function as a computer based on various programs, data, and the like. The data recording unit 16, RAMs 32 and 55, ROMs 33 and 56, database 58, flash memory, and the like constitute a recording medium. An MPU or the like can be used instead of the CPUs 31 and 54 as the arithmetic unit.

  Next, a basic operation when the navigation system having the above configuration is used as a route guidance system will be described.

  First, when the operation unit 34 is operated by the driver and the navigation device 14 is activated, a navigation initialization processing unit (not shown) of the CPU 31 performs navigation initialization processing, and the current location and direction sensor detected by the GPS sensor 15. 18 reads the vehicle direction detected by 18 and initializes various data. The matching processing means (not shown) of the CPU 31 performs matching processing, and based on the trajectory of the read current location and the shape, arrangement, etc. of each road link constituting the road around the current location, the current location is any road. The current location is identified by determining whether it is located on the link.

  Subsequently, a basic information acquisition processing unit (not shown) of the CPU 31 performs a basic information acquisition process and acquires the map data by reading it from the data recording unit 16 or receiving it from the information center 51 or the like via the communication unit 38. And get. In addition, when acquiring map data from the information center 51, the said basic information acquisition process means downloads the received map data to flash memory. Moreover, when acquiring map data via the communication part 38, a program can also be acquired.

  A display processing unit (not shown) of the CPU 31 performs a display process and forms various screens on the display unit 35. For example, the map display processing means of the display processing means performs map display processing, forms a map screen on the display unit 35, and displays the vehicle position, a map around the vehicle position, and the vehicle direction on the map screen. . Therefore, the driver can drive the vehicle according to the vehicle position, the map around the vehicle position, and the vehicle direction.

  Further, when the driver operates the operation unit 34 to input a destination, a destination setting processing unit (not shown) of the CPU 31 performs a destination setting process to set the destination. Note that the departure place can be input and set as necessary. Moreover, a predetermined point can be registered in advance, and the registered point can be set as a destination. Subsequently, when the driver operates the operation unit 34 to input a search condition, a search condition setting processing unit (not shown) of the CPU 31 performs a search condition setting process to set the search condition.

  When the destination and search conditions are set in this way, the route search processing means (not shown) of the CPU 31 performs route search processing, reads the current location, destination, search conditions, and the like from the data recording unit 16. Based on the current location, the destination, and the search data, a route from the departure point to the destination represented by the current location is searched based on the search condition, and route data representing the searched route is output. In this case, the route having the smallest total link cost assigned to each road link is set as the searched route.

  Subsequently, a guidance processing means (not shown) of the CPU 31 performs guidance processing and provides route guidance. For this purpose, the route display processing means of the guidance processing means performs route display processing, reads the route data, and displays the searched route on the map screen according to the route data. In this case, if necessary, the voice output processing means of the guidance processing means performs voice output processing and outputs a search route by voice from the voice output unit 37 to perform route guidance.

  The information center 51 can perform route search processing. In that case, the CPU 31 transmits the current location, the destination, search conditions, and the like to the information center 51. When the information center 51 receives the current location, destination, search conditions, etc., the route search processing means (not shown) of the CPU 54 performs route search processing similar to that of the CPU 31 and reads the search data from the database 58 to obtain the current location, destination. Based on the location and the search data, a route from the departure point to the destination is searched under the search conditions, and route data representing the searched route is output. Subsequently, a transmission processing unit (not shown) of the CPU 54 performs transmission processing and transmits the route data to the navigation device 14. Therefore, in the navigation device 14, when the basic information acquisition processing means receives the route data from the information center 51, the guidance processing means performs route guidance as described above.

  In addition, when the display processing unit reads the statistical data and history data from the data recording unit 16 or receives traffic information via the communication unit 38, the display processing unit converts the traffic information into a traffic jam zone as a traffic condition index. The traffic jam zone is displayed along the road on the map screen. In this case, the traffic jam zone is displayed so as to extend from the traffic jam start point to the traffic end point, and the color of the traffic jam zone is changed to red, orange, or green depending on the level of traffic jam. In this way, the driver can know the traffic congestion situation of the road on the route on which the vehicle is scheduled to travel, the searched route, and the like.

  Incidentally, in the data recording unit 16, the statistical data and the history data are recorded on, for example, a disk. Therefore, when the traffic information of the statistical data and the history data is converted into a traffic jam zone and displayed on the map screen, the display processing means reads the traffic information from the disk, converts it into the traffic jam zone, and converts the traffic jam zone into the traffic jam zone. Display on the map screen.

  However, if the next traffic information is read from the disk in the same way when the current location changes as the vehicle travels, the processing time for reading becomes longer, and the load applied to the CPU 31 increases accordingly. End up.

  On the other hand, when the current traffic information is acquired and converted into a traffic jam zone and displayed on the map screen, a recording processing unit (not shown) of the CPU 31 performs a recording process and records the acquired traffic information on, for example, the disk. The display processing means reads the traffic information from the disk, converts it into a traffic jam zone, and displays the traffic jam zone on the map screen.

  In this case, if the next traffic information is read from the disk in the same manner when the current location changes as the vehicle travels, the processing time for reading becomes longer, and the load applied to the CPU 31 increases accordingly. End up. Further, as the traffic condition changes on the actual road as time passes, new traffic information needs to be read from the disk when the traffic information changes, and the processing time for reading becomes even longer. The load applied to is further increased.

  Therefore, a cache memory included in the navigation processing unit 17 is used as a memory, and traffic information read from the disk is recorded as cache data in the cache memory. The cache memory is constituted by a plurality of buffers, and not only the one built in the CPU 31 but also one connected to the CPU 31 can be used. Also, DRAM, SRAM or the like is used as the cache memory.

  FIG. 4 is a conceptual diagram showing an example of a cache memory in the embodiment of the present invention, and FIG. 5 is a diagram showing details of the cache memory in the embodiment of the present invention.

  In the figure, AR1 is a cache management area, AR4 is a recording area, and the recording area AR4 is partitioned into a plurality of partition areas categorized according to the size of the data size that is an attribute of the cache data. The large cache area AR5, which is the first partition area for recording cache data within the range of 1000 to 101 [bytes], the data size being the next largest, and the range of 100 to 11 [bytes] A middle cache area AR6, which is a second partition area for recording cache data in the memory, and a third partition area for recording cache data having a small data size in the range of 10 to 1 [byte]. It consists of a small cache area AR7. The large cache area AR5, middle cache area AR6, and small cache area AR7 are fixed at predetermined positions in the cache memory and are not changed.

  Then, a cache area pa (a = 1, 2,..., U) is set in the large cache area AR5, and cache data within a range of 1000 to 101 [bytes] is recorded in each cache area pa. A cache area qb (b = 1, 2,..., V) is set in the area AR6, cache data within a range of 100 to 11 [bytes] is recorded in each cache area qb, and a cache area is stored in the small cache area AR7. rc (c = 1, 2,..., w) is set, and cache data within a range of 10 to 1 [byte] is recorded in each cache area rc. In this case, the cache data is recorded for each area for dividing the map data, for example, meshes, parcels, and the like.

  The cache size of each cache area pa is 1000 [bytes] and the cache size of each cache area qb is so that the cache data having the maximum data size can be recorded in each cache area pa, qb, rc. The cache size of each cache area rc is set to 10 [bytes] at 100 [bytes].

  The cache management area AR1 includes a large block management area AR11 as a first management area corresponding to the large cache area AR5, and a medium block as a second management area corresponding to the middle cache area AR6. The management area AR12 is set to correspond to the small cache area AR7, and the small block management area AR13 as the third management area is set. Then, management data dai (i = 1, 2,..., U) representing a position in the large cache area AR5 is recorded in the large block management area AR11 for each cache area pa, and each medium area management area AR12 stores each piece of data. For each cache area qb, management data dbi (i = 1, 2,..., V) representing the position in the middle cache area AR6 is recorded, and for each cache area rc, the small cache area AR7 is recorded in the small block management area AR13. Management data dci (i = 1, 2,..., W) representing the position of is recorded.

  Each of the management data dai, dbi, and dci includes a cache head address that represents the head address of the recording area AR4, and an offset value from the cache head address of each of the cache areas pa, qb, rc. In the present embodiment, the cache head address and the offset value from the cache head address are used as the management data dai, dbi, and dci, but each large cache area is used instead of the cache head address. It is possible to use partition area head addresses representing the head addresses of AR5, middle cache area AR6, and small cache area AR7, and offset values from the partition area head addresses of cache areas pa, qb, and rc.

  Next, a cache management method for managing the cache memory having the above configuration will be described.

  FIG. 6 is a flowchart showing the operation of the cache memory setting processing means in the embodiment of the present invention.

  A cache memory setting processing unit (not shown) of the CPU 31 (FIG. 1) performs a cache memory setting process to set the cache memory. For this purpose, the cache management area setting processing means of the cache memory setting processing means performs the cache management area setting process, sets the cache management area AR1 (FIG. 4) in the cache memory, and then continues to the cache memory setting processing means. The recording area setting processing means performs recording area processing, sets a recording area AR4, and divides the recording area AR4 into a large cache area AR5, a middle cache area AR6, and a small cache area AR7.

  Subsequently, the cache head address setting processing means of the cache memory setting processing means performs a cache head address setting process to set the cache head address of the recording area AR4. Then, the cache management area setting processing means corresponds to the large cache area AR5, the medium cache area AR6, and the small cache area AR7 in the cache management area AR1. A block management area AR13 is set.

  In this way, the large cache area AR5, the middle cache area AR6, and the small cache area AR7 are set at fixed positions in the cache memory, and each cache is set in the large cache area AR5, the middle cache area AR6, and the small cache area AR7. Areas pa, qb, rc are set, and management data dai, dbi, dci for managing the positions of the cache areas pa, qb, rc are recorded in the cache management area AR1. Note that the offset value of each cache area pa, qb, rc can be calculated and recorded based on the cache size of each cache area pa, qb, rc.

  As described above, in the present embodiment, the large cache area AR5, the middle cache area AR6, and the small cache area AR7 are set at fixed positions in the recording area AR4, and the cache areas pa, qb, rc Since the AR5, the middle cache area AR6, and the small cache area AR7 are set at fixed positions, there is no need to set them close to the cache head address side of the recording area AR4, and the cache areas pa, qb, rc Management becomes easy. Therefore, for example, even when the vehicle moves or time elapses, predetermined traffic information becomes unnecessary, and cache data in a predetermined cache area among the cache areas pa, qb, rc is deleted. Since the predetermined cache area is a free area, it is not necessary to rearrange the cache areas pa, qb, rc. As a result, the load applied to the CPU 31 can be reduced.

  Further, since the cache areas pa, qb, and rc are not rearranged, it is not necessary to change the addresses for representing the positions of the cache areas pa, qb, and rc. Therefore, it becomes easy to specify an address when writing or reading necessary cache data, and the time required for writing and reading can be shortened.

  Further, since the recording area AR4 is partitioned into a large cache area AR5, a middle cache area AR6, and a small cache area AR7 having different cache sizes, the number of cache areas pa, qb, rc can be increased, and the convenience of the cache memory is increased. Can be improved.

  Since the cache data is recorded in an appropriate cache area among the large cache area AR5, the middle cache area AR6, and the small cache area AR7 depending on the data size, the use efficiency of the cache memory can be increased.

Next, a flowchart will be described.
Step S1: The cache management area AR1 is secured.
Step S2: The recording area AR4 is set.
Step S3: The cache head address is set, and the process is terminated.

  Next, the operation of the recording processing unit when the data recording unit 16 reads cache data from, for example, a disk and records it in the cache areas pa, qb, rc will be described.

  FIG. 7 is a flowchart showing the operation of the recording processing means in the embodiment of the present invention, and FIG. 8 is a diagram showing a cache management area determination map in the embodiment of the present invention.

  First, the recording processing means reads the offset value of the area where the cache data in the disk is recorded and the data size of the cache data, and reads the cache data from the disk based on the offset value. Next, the attribute determination processing means of the recording processing means performs attribute determination processing, determines the data size of the cache data, refers to the cache management area determination map of FIG. 8, and the data size is the large cache area AR5. It is determined whether it is within the range of (FIG. 4), whether it is within the range of the middle cache area AR6, and whether it is within the range of the small cache area AR7.

  Then, the management area determination processing means of the recording processing means performs the management area determination process, and determines that the predetermined management area is a corresponding management area representing the corresponding management area based on the determination result of the attribute determination process. To do. That is, when the management area determination processing means is within the range of the large cache area AR5, it determines that the large block management area AR11 (FIG. 5) is the corresponding block management area and is within the range of the middle cache area AR6. In this case, it is determined that the middle block management area AR12 is the corresponding block management area, and if it is within the small cache area AR7, the small block management area AR13 is determined to be the corresponding block management area.

  Subsequently, the offset value determination processing unit of the recording processing unit performs an offset value determination process, and when recording cache data in a predetermined cache area, calculates an offset value based on the address of the predetermined cache area, When the offset value is searched in the corresponding block management area and the same offset value exists, the management data change processing means of the recording processing means performs management data change processing, searches for management data of the offset value, Move to the beginning of the corresponding block management area. If there is no same offset value, the management data change processing means obtains the cache start address of the last management data in the corresponding block management area and sets the offset value as the offset value of the last management data. The management data is moved to the head of the corresponding block management area.

  Subsequently, the data writing processing means of the recording processing means performs data writing processing and writes the cache data in the cache area corresponding to the moved management data. In this way, the cache data can be written to a selected cache area among the large cache area AR5, the middle cache area AR6, and the small cache area AR7 based on the determination result of the attribute of the cache data.

Next, a flowchart will be described.
Step S11: Read the offset value and data size, and read the cache data.
Step S12: Determine the data size.
Step S13: It is determined whether or not it is within the large cache area AR5. If it is within the large cache area AR5, the process proceeds to step S14. If it is not within the large cache area AR5, the process proceeds to step S15.
Step S14: The large block management area AR11 is set as the corresponding block management area.
Step S15: It is determined whether the area is within the middle cache area AR6. If it is within the middle cache area AR6, the process proceeds to step S16. If it is not within the middle cache area AR6, the process proceeds to step S17.
Step S16: The middle block management area AR12 is set as the corresponding block management area.
Step S17: It is determined whether or not it is within the small cache area AR7. If it is within the small cache area AR7, the process ends in step S18. If it is not within the small cache area AR7, the process ends.
Step S18: The small block management area AR13 is set as the corresponding block management area.
Step S19: Search for an offset value.
Step S20: Determine whether there is the same offset value. If the same offset value exists, the process proceeds to step S21. If not, the process proceeds to step S22.
Step S21: Search for management data.
Step S22: The cache start address of the last management data is acquired.
Step S23: An offset value of the last management data is set.
Step S24: The management data is moved to the top.
Step S25: The cache data is written in the cache area, and the process is terminated.

  In the present embodiment, the cache data is recorded in an appropriate cache area among the large cache area AR5, the middle cache area AR6, and the small cache area AR7 depending on the data size. In this case, the cache data may be recorded in an appropriate cache area among the large cache area AR5, the middle cache area AR6, and the small cache area AR7 depending on the number of road links of the traffic information representing the attribute of the cache data. it can. That is, when the number of road links included in the cache data is large, the cache area pa of the large cache area AR5 and when the number of road links included in the cache data is the next largest, the cache area qb of the middle cache area AR6 In addition, when the number of road links included in the cache data is small, the cache data is recorded in the cache area rc of the small cache area AR6.

  For this purpose, the attribute determination processing means of the recording processing means performs attribute determination processing to determine the number of road links in the cache data, and whether or not the number of road links is within the large cache area AR5. It is determined whether it is within the middle cache area AR6 and whether it is within the small cache area AR7.

  In this embodiment, one large cache area AR5, one middle cache area AR6, and one small cache area AR7 are set in the recording area AR4. However, in the other embodiments, Can arbitrarily divide the large cache area AR5, the medium cache area AR6, and the small cache area AR7, and set any number of large cache areas, medium cache areas, and small cache areas. Also in this case, the positions of the large cache area, the middle cache area, and the small cache area are fixed and are not changed.

  In this embodiment, a cache memory is arranged in the CPU 31, but a CPU can be arranged in the data recording unit 16, and a cache memory can be arranged in the CPU. .

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a block diagram which shows the navigation system in embodiment of this invention. It is a conceptual diagram which shows the example of the conventional cache memory. It is a conceptual diagram which shows the other example of the conventional cache memory. It is a conceptual diagram which shows the example of the cache memory in embodiment of this invention. It is a figure which shows the detail of the cache memory in embodiment of this invention. It is a flowchart which shows operation | movement of the cache memory setting process means in embodiment of this invention. It is a flowchart which shows operation | movement of the recording process means in embodiment of this invention. It is a figure which shows the cache management area | region determination map in embodiment of this invention.

Explanation of symbols

31 CPU
AR1 Cache management area AR4 Recording area AR5 Large cache area AR6 Medium cache area AR7 Small cache area AR11 Large block management area AR12 Medium block management area AR13 Small block management area

Claims (6)

  A recording process for determining cache memory attributes divided into a plurality of partition areas having different cache sizes and cache data, and recording the cache data in a selected partition area among the partition areas based on the determination result And a navigation system.   The cache memory includes a cache management area composed of a plurality of management areas for recording management data, and the recording processing means is attribute determination processing means for determining an attribute of the cache data, and determination by the attribute determination processing means 2. A management area determination processing unit that determines that a predetermined management area is a corresponding management area based on a result, and a data write processing unit that writes the cache data in a partition area corresponding to the corresponding management area. The navigation system described in.   The navigation system according to claim 1 or 2, wherein the attribute is a data size of cache data.   The navigation system according to claim 1 or 2, wherein the cache data is traffic information, and the attribute is the number of road links.   A cache memory, wherein the cache memory is partitioned into a plurality of partition areas having different cache sizes, and the cache data is recorded in the partition areas selected based on the attribute determination result. Determining the attribute of the cache data, selecting a predetermined partition area among the plurality of partition areas having different cache sizes set in the cache memory based on the determination result, and recording the cache data Cache management method.

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