JP2005196348A - Information display device, control method therefor and information display program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information display device capable of more comfortably displaying composite document data on a portable information appliance, and to provide a control method therefor. <P>SOLUTION: This display device comprises at least a drawing part 5, a display part 6, a display 7, a storage device 3, and a memory management module, and has a page management module securing a plurality of page buffers in an area of the storage device 3 not managed by the memory management module. The drawing part 5 and the display part 6 are configured such that they can access the plurality of page buffers. The drawing part 5 performs drawing to the page buffer designated by the page management module, and the display part 6 reads the data from the page buffer designated by the page management module and performs display. Thereby, a user can call a page which the user has displayed once, at high speed, and can obtain a comfortable using feeling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information display device that performs screen display in units of pages and a control method thereof, and in particular, an information display device that enables more diverse and high-speed page display by efficiently performing buffer control, and a control method and information display thereof. Regarding the program.

In recent years, with the improvement of the performance of information display devices, techniques relating to document display and the like have become more complex in search of more various information displays. For example, in addition to text data indicating the original document content to be displayed, compound document data including supplementary information indicating the font format, size, color, and other character formats, and additional display of images such as backgrounds and illustrations Are becoming widely used.
Currently, a compound document display program called a browser is incorporated into a general-purpose personal computer that is widely used as a display device for compound document data. Since the computer is equipped with a high-performance microprocessor and graphics accelerator, a comfortable display can be obtained even with complex compound document data.

On the other hand, with the spread of portable information devices in recent years, there has been a demand for displaying complex document data comfortably on portable information devices.
Conventionally, in the final stage of various information display devices, display data is configured as a collection of pixel data (rasterized image) indicating the density and color of a point, and the display data is transferred to a display to perform actual display. The method is used. These are realized by using a conventional memory control method as shown in Non-Patent Document 1.
Microsoft Corporation, “Microsoft Windows NT Workstation 4.0 Resource Kit”, ASCII Co., Ltd., April 11, 1997, first edition, second print, p.352-353

  However, when the above-described compound document display program comprising the conventional memory control method as shown in Non-Patent Document 1 is used to display the compound document data by operating the portable information device, the display operation is very slow. There was a problem of becoming. Although these problems did not appear when operating on a high-performance general-purpose personal computer, it would be comfortable for the user to operate on a portable information device with relatively low processing performance. It will be a difficult situation.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an information display device capable of displaying compound document data at high speed on a portable information device and a control method thereof.

  In order to solve the above problems, an information display device of the present invention includes a memory (for example, the storage device 3 in FIG. 1) capable of storing display data to be displayed, and the display data in a predetermined area in the memory. Write writing means (for example, the drawing unit 5 in FIG. 1) and display control means (for example, the display in FIG. 1) that reads the display data written in the predetermined area and displays it on the display for each page as a display unit. Unit 6) and memory management means (for example, the memory management module 10a in FIG. 2) for performing memory management corresponding to the memory management function of the operating system, and a system area secured on the memory by the memory management means An information display device that performs processing by forming a heap area in the management area (for example, the management area of the memory management module in FIG. 3), A dedicated area (for example, the management area of the page management module in FIG. 3) for storing the display data is secured outside the system area on the memory, and the display data storage area for each page is provided in the dedicated area. It further includes page buffer management means (for example, page management module 11c in FIG. 2) that forms a page buffer, and the writing means and display control means are configured to be accessible to the dedicated area, and the writing means The display data is written in a predetermined page buffer in a dedicated area, and the display control means reads out the display data written in the predetermined page buffer in the dedicated area and displays it on the display.

Here, the memory management means performs memory management similar to the memory management function of a general-purpose operating system, and can be realized by a memory management function of the operating system or a memory management function realized by an application program. Is possible.
With such a configuration, in a display device having the concept of pages, it becomes possible to efficiently use an empty area of a memory as a page buffer, and display complex document data at high speed. As a result, the user can call a page once displayed at high speed, and a comfortable feeling of use can be obtained.

Note that the dedicated area can be secured directly on the memory by the page buffer management unit or can be secured through the memory management unit.
Further, the present invention is characterized in that the memory management means can manage the dedicated area.
With such a configuration, the free area of the memory can be used efficiently.

Further, the present invention is characterized in that the system area is secured from the upper address side in the memory, and the dedicated area is secured from the lower address side in the memory.
With such a configuration, a situation where the system area and the dedicated area overlap can be avoided as much as possible, and the memory area can be used efficiently.

Note that the system area and the dedicated area do not matter about specific addresses in the memory, and each area can be secured at addresses logically assigned as upper and lower.
Further, the present invention is characterized in that the capacity of the page buffer is a fixed value corresponding to the amount of rasterized image data for one page of display data.

The present invention also provides a compression means for compressing the display data to be written by the writing means by a predetermined compression method, and a decoding means for decoding the compressed display data to be read by the display control means. Is further provided.
With such a configuration, the memory area can be used efficiently.
Further, the present invention provides an analysis / shaping unit that generates intermediate format data obtained by performing document structure analysis and layout processing on the display data to be written by the writing unit, and reading by the display control unit Conversion means for converting the target intermediate format data into a rasterized image.

With such a configuration, display data can be displayed at higher speed. Furthermore, in addition to text data that indicates the document content that should be displayed, compound document data that includes auxiliary information that indicates character formatting such as font shape, size, and color, and additional display of images such as backgrounds and illustrations It is effective in displaying.
Further, the present invention is characterized in that the page buffer can change its capacity in accordance with the data amount of the display data written by the writing means.

With such a configuration, the size of the page buffer can be made appropriate, and the memory area can be used efficiently.
Further, the present invention is characterized in that each of the system area and the dedicated area is secured in a fixed address range.
With such a configuration, a certain capacity can be secured for each region. In addition, memory fragmentation can be reduced.

Further, according to the present invention, the page buffer management means and the memory management means can change the sizes of the system area and the dedicated area to each other in accordance with the usage state of the system area and the dedicated area. It is characterized by that.
Further, the present invention is characterized in that the sizes of the heap area and the dedicated area can be mutually changed based on the capacity of the free area in the heap area in the system area.

With such a configuration, it becomes possible to efficiently use the free area of the memory according to the processing contents of the information display device, and to increase the operation speed.
Further, the present invention is characterized in that when the page buffer management means releases the page buffer, the page buffer located at an address closer to the heap area is released.

With such a configuration, memory fragmentation can be reduced.
Further, according to the present invention, when the page buffer management unit releases the page buffer, display data having a page number farther from the page number of the display data read by the display control unit is stored. The page buffer is released.

  In addition, the present invention further includes display order storage means (for example, the display history recording unit 11b in FIG. 2) that stores the order of display data stored in the page buffer and displayed in the display. When the buffer management means releases the page buffer, the buffer management means releases the page buffer in which display data displayed in an earlier order is stored based on the order stored in the display order storage means. Features.

  The present invention further includes display time storage means (for example, the display history recording unit 11b in FIG. 2) for storing the time displayed on the display for the display data stored in the page buffer. When the buffer management unit releases the page buffer, the buffer management unit releases the page buffer in which display data displayed at an earlier time is stored based on the time stored in the display time storage unit. Features.

  The present invention further includes display number storage means (for example, the display history recording unit 11b in FIG. 2) for storing the number of times the display data stored in the page buffer is displayed on the display. When the buffer management unit releases the page buffer, the buffer management unit releases the page buffer in which display data having a smaller number of times of display is stored based on the number of times stored in the display number storage unit. Features.

With such a configuration, it is possible to release a page buffer in which display data that is unlikely to be used is stored, and it is possible to efficiently use a memory area.
The present invention also provides a memory capable of storing display data to be displayed, writing means for writing the display data in a predetermined area in the memory, and reading the display data written in the predetermined area for display. Display control means for displaying on a display for each page as a unit, and memory management means for performing memory management corresponding to the memory management function of the operating system, in the system area secured on the memory by the memory management means And a method for controlling the information display device that performs processing by forming a heap area, wherein a dedicated area for storing the display data is secured outside the system area on the memory, and the dedicated area includes the A page buffer, which is a display data storage area for each page, is formed, and the display data is stored in a predetermined page buffer in the dedicated area. Write data, reads the display data written in the predetermined page buffer of the dedicated region, and wherein the to be displayed on the display.

  The present invention also provides a memory capable of storing display data to be displayed, writing means for writing the display data in a predetermined area in the memory, and reading the display data written in the predetermined area for display. Display control means for displaying on a display for each page as a unit, and memory management means for performing memory management corresponding to the memory management function of the operating system, in the system area secured on the memory by the memory management means In addition, an information display program for controlling an information display device that performs processing by forming a heap area, the information display device is configured such that the writing means and the display control means can access the dedicated area, A dedicated area for storing the display data is secured outside the system area on the memory, and the dedicated area A page buffer management function for forming a page buffer, which is a storage area for display data for each page, in the area, in the predetermined page buffer in the dedicated area, writing the display data by the writing means, and The display data can be read by display control means.

  With such a configuration, in a display device having the concept of pages, it becomes possible to efficiently use an empty area of a memory as a page buffer, and display complex document data at high speed. As a result, the user can call a page once displayed at high speed, and a comfortable feeling of use can be obtained.

Hereinafter, an embodiment of an information display device according to the present invention will be described with reference to the drawings.
(First embodiment)
First, the configuration will be described.
<Hardware configuration>
FIG. 1 is a diagram showing a hardware configuration of the information display device according to the first embodiment of the present invention.

1, an information display device of the present invention includes a CPU (Central Processing Unit) 1, a ROM (Read Only Memory) 2, a storage device (RAM: Random Access Memory) 3, an I / O 4, a graphic accelerator (GA) 5, and a display controller. (DC) 6 and display 7.
The CPU 1, ROM 2, storage device (RAM) 3, I / O 4, graphic accelerator 5, and display controller 6 are connected to each other via a bus 8, and a keyboard, touch panel, mouse, audio (not shown) are connected via the I / O 4. It is connected to a circuit, a network interface (I / F), a memory card interface, a timer (time storage / update means), and the like.

The CPU 1 controls the entire information display device, and executes various programs such as display of compound document data by executing various programs (system program 10 or application program described later) stored in the ROM 2. .
The ROM 2 stores later-described software (control program) for controlling the operation of the CPU 1.

The RAM 3 stores a control program or temporarily holds generated data when the CPU 1 performs a control operation. The memory configuration (memory map) of the RAM 3 will be described later.
The I / O 4 is an interface that controls signals to be input / output when the CPU 1 transmits / receives data to / from a keyboard, touch panel, mouse, audio circuit, network interface (I / F), memory card interface, timer, and the like.

The graphic accelerator 5 generates rasterized data by executing a drawing command for a predetermined page input by the CPU 1.
The graphic accelerator 5 includes a register (not shown). In this register, a page buffer start address indicating a start address of a page buffer (described later) to which a drawing page (page written to the page buffer) is written, It is possible to store a drawing command data start address indicating a dress in which drawing command data to be acquired is stored. The graphic accelerator 5 can set a page buffer for writing a drawing page and drawing command data to be executed by storing a specific address in this register.

The graphic accelerator 5 can read and write memory contents at an arbitrary position on the RAM 3 by bus master access.
Furthermore, the graphic accelerator 5 includes an image compression unit 5a that can compress drawing data that is a raster image by a predetermined compression method.
The image compression unit 5a is used when the drawing data is compressed and stored in the page buffer. Therefore, the image compression unit 5a may be provided only when necessary. Further, as a compression method in the image compression unit 5a, since the display controller 6a scans image data line-sequentially, a technique suitable for line-sequential scanning, for example, run length method, differential encoding, predictive encoding, or A compression technique combining them is preferable.

The display controller 6 reads display data stored in a predetermined page buffer of the RAM 3 and causes the display 7 to display the read display data by line sequential scanning.
Further, the display controller 6 includes a register (not shown), and stores a page buffer start address indicating a start address of a display page (a page read from the page buffer and displayed on the display 7) in the register. Is possible. The display controller 6 can set a page buffer as a display page reading destination by storing a specific address in this register.

Further, the display controller 6 can read the memory contents at an arbitrary position on the RAM 3 by bus master access.
Further, the display controller 6 includes an image decoding unit 6a that decodes display data stored in a state compressed by the image compression unit 5a.
Note that the image decoding unit 6a is used only when data compression is performed by the image compression unit 5a, and therefore only needs to be provided when necessary.

The display 7 is connected to the display controller 6 and displays an image based on the output of the display controller 6.
In the above description, the case where the information display device has the bus master access function has been described. However, when it is difficult to provide the bus master access function in terms of circuit design, it is known as one of existing technologies. As described above, it is possible to add a DMA circuit on the bus 8 and perform data transfer by DMA.
<Software configuration>
Next, the software configuration will be described.

FIG. 2 is a diagram showing a software configuration of the information display apparatus according to the first embodiment of the present invention.
As shown in FIG. 2, software that functions on the information display device is mainly configured by an OS (system program) 10 and a browser (application program) 11.

The OS 10 includes a memory management module 10a, and the browser 11 includes an analysis / shaping unit 11a, a history management module (display history recording unit) 11b, and a page management module 11c.
The memory management module 10a performs processing performed by a general-purpose operating system, such as securing or releasing an area in the memory 3 in which the program of the OS 10 or the browser 11 is stored and a heap area used by the OS 10 or the browser 11. The area on the memory 3 secured by the memory management module 10a is hereinafter referred to as “system area” as appropriate.

The analysis / shaping unit 11a shows the text data to be displayed, the character format such as the font shape, size, and color set in the text data, and additional display of images such as backgrounds and illustrations. Analyze compound document data including auxiliary information. Then, the analysis / shaping unit 11a outputs intermediate format data that is a result of performing the necessary shaping or format change.
As described above, by installing the analysis / shaping unit 11a, it is possible to display data having a complicated format such as HTML and XML, which are existing technologies, and the display size, resolution, display orientation, and the like. Even when there is a change, a suitable display can always be performed.

  Here, the intermediate format data may be in any format as long as it can be rendered, but in the present embodiment, the graphic accelerator 5 directly interprets it as a rendering command and renders a raster image. A two-dimensional vector graphics format that can be used. If the data to be displayed is simple document data or image data that does not include layout information, the analysis / shaping unit 11a is not used.

The history management module 11b stores the page number of the display data stored in each page buffer in association with the display order, the displayed time, and the displayed number of times.
The page management module 11c reserves an area not used as a system area in the memory 3 as a dedicated area for forming a page buffer (hereinafter referred to as “page buffer dedicated area”). Then, the page management module 11c forms a predetermined number of page buffers in the page buffer dedicated area, and manages writing and reading of data with respect to the page buffer, formation and release of the page buffer, and the like.

The system program 10 and the application program 11 are stored in the ROM 2, and part or all of the system program 10 and the application program 11 are loaded into the RAM 3 when the power is turned on or reset.
At this time, when the OS (system program) 10 corresponding to the in-place execution technique which is an existing technique is employed, the system program 10 and the application program 11 are directly executed from the ROM 2. Therefore, in such a case, the program or the like is not loaded into the RAM 3, but the system area is secured in the memory 3 in common. In the present embodiment, an example in which in-place execution is not performed is shown, but the presence or absence of in-place execution technology does not change the gist of the present invention.
<Memory configuration>
Next, a memory configuration (memory map) will be described.

FIG. 3 is a diagram showing a memory configuration of the information display device according to the first embodiment of the present invention.
As shown in FIG. 3, in addition to the system program 10 and the application program 11, the RAM 3 stores a heap area 25 and page buffers 21, 22, 23, and 24 (area division). In the memory map shown in FIG. 3, it is assumed that the system program 10 is stored from the address 0, and the address 0 is the upper address here.

The memory management module 10a incorporated in the OS manages all remaining memory areas except for the page buffers 21, 22, 23, and 24.
The page management module 11c incorporated in the application program 11 secures at least one, usually a plurality of page buffers, in a memory area not managed by the memory management module 10a. Note that the page management module 11c may be incorporated in the system program.

  The heap area 25 for use as a work memory by the system program 10 and the application program 11 can store a plurality of memory areas, and dynamically secures or releases a memory area according to usage. To do. Management of the heap area 25 is managed by a heap area management module that is an existing technique incorporated in the memory management module 10a, and fragmentation elimination processing that is an existing technique is also performed. The heap area 25 can be divided into a used area 26 and a free area 27, and the size of the free area 27 changes as the processing of the CPU 1 proceeds.

  The page management module 11c holds a page management table as information for managing the plurality of page buffers 21, 22, 23, and 24. In the page management table, as entry information indicating each page buffer, a flag indicating whether it is in use or empty, a number for identifying the type of stored data, a number indicating the use of the page buffer (the above-mentioned display page and Drawing page, number indicating the page to save data, etc.), page buffer start address, page buffer size, page number, serial number indicating display order, last displayed time, display The information such as the number of times of being stored is stored.

  In order to speed up the search process, the page management table is preferably arranged in a memory area separate from the page buffers 21, 22, 23, and 24. However, as used in existing technology, Each entry information can be held in the head portion of each page buffer 21, 22, 23, 24 in the form of a buffer header. In this case, the page management table is configured in the link chain format, and it is necessary to store an address indicating the next page buffer header in the entry information. Further, the page management module 11c, as information necessary for managing the page buffers 21, 22, 23, 24, includes the total number of pages in the page buffer, the start address of the free area, the size of the free area, and the like as necessary. It is good also as holding information.

  The number of page buffers and the size per page are set to appropriate fixed values at the time of system design. The appropriate value varies greatly depending on the resolution and the number of colors of the display 7, the installed memory capacity, the use of the system, and the like. For example, when a general reading terminal is assumed, the appropriate value is large. This is equivalent to the storage capacity for one screen of the display, and it is desirable to secure at least two page buffers, preferably as many as possible if the capacity of the mounted memory is allowed. In that case, the user can easily use the system without being aware of the setting, and the more the number of page buffers is set, the more the operation when the user refers to a past page. It is fast and can be used comfortably.

  A setting change program that can set the number and capacity of page buffers can be incorporated into the system program 10 or the application program 11. In that case, in a case where the system is diverted to another use, a more appropriate operation according to the use after diversion becomes possible. For example, when a reading terminal is diverted to an advertisement display terminal, the page is not returned by the user, so that a minimum number of page buffers is required. By using the memory area freed by the reduction of the page buffer for storing advertisement data, more advertisements can be displayed.

  Further, the page management module 11c may be configured to dynamically change the number and capacity of page buffers. In this case, the page buffer is secured or released by the page management module 11c as necessary. When a new page buffer is secured, a new page buffer is secured in an empty area of the memory area managed by the page management module 11c. When releasing an unnecessary page buffer, the page management module 11c releases an unnecessary page buffer area and adds it to an empty area. When releasing the page buffer, it is preferable to perform the fragmentation elimination process which is an existing technique. That is, when a situation occurs in which a plurality of free areas in the page buffer remain in a fragmented manner, the page buffer being used is moved to perform the work of combining the fragmented free areas into one.

  When the image compression unit 5a and the image decoding unit 6a are used, the capacity of the compressed raster image data after compression varies greatly depending on the contents to be displayed. Therefore, the above-described fixed size page buffer securing method can be predicted by an algorithm. It is necessary to unify the buffer size to the maximum size (usually equal to the image data size before compression), and an unused waste area tends to occur in the latter half of each page buffer.

Therefore, by adopting a configuration in which the page management module 11c dynamically changes the number and capacity of page buffers, such waste is eliminated and the memory can be used efficiently.
In this example, the system area is secured on the upper address side and the page buffer is secured on the lower address side, but these are secured in the opposite area (the page buffer is secured on the upper address side, It is also possible to secure a system area on the lower address side). In other words, the system area and the area where the page buffer is secured can be secured at addresses that are logically assigned to the upper and lower addresses without causing a specific address in the memory map. .

Next, the operation will be described.
As an explanation of the operation, as an application example of the information display device according to the present invention, first, assuming a reading terminal adopting a non-memory display body as a display, the user browses the second page of the document and then the third page. The case of going to the eye and then returning to the second page again to confirm the previous sentence will be described using eight patterns based on the state change of the page buffer as an example.

Non-memory display bodies include CRTs and liquid crystal displays that have been widely used until now, and display data must be periodically transmitted in accordance with a cycle called a refresh rate. The general refresh rate of a non-memory display is about 50 to 120 times per second, and display data for one screen must be transmitted every time. For this reason, the display unit 6 must always transmit display data.
[Pattern 1]
FIG. 4 is a diagram illustrating a state change of the page buffer in the pattern 1.

  In the pattern 1, a non-memory display body is used as the display 7, and the analysis / shaping unit 11a, the image compression unit 5a, and the image decoding unit 6a are not used. The size of the page buffer per sheet is equivalent to the storage capacity of the display, and the number of sheets depends on a value determined at the time of system design or a setting change program. To do.

  In FIG. 4A, the page buffer 21 stores the raster image of the first page that has already been browsed, and the page buffer 22 stores the raster image of the second page that is currently being browsed. . The page buffers 23 and 24 are free. The page management module 11c provided in the application program 11 designates the page buffer 22 as a display page and causes the display controller 6 to perform display. The display controller 6 continues to transfer the contents of the page buffer 22 to the display 7 at a constant cycle.

Next, in FIG. 4 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program is in an empty state from the page buffer. Search for a thing and use the detected page buffer as a new drawing page.
If there is no remaining page buffer, select an appropriate page buffer from the currently used page buffers, and use that page buffer as a new drawing page buffer by assuming that the page buffer is empty. To do. Selection of an appropriate page buffer can be performed in the following manner. That is,
1) Search the page buffer that stores the data associated with the page number farthest from the page number that the user instructs to display from the existing page buffers, and target the detected page buffer. To do.
2) Using the display history recording unit 11b provided in the application program 11 that records the page number instructed to be displayed by the user in association with the display order, the oldest order is associated with the oldest page buffer. The page buffer storing the data of the page number to be searched is searched, and the detected page buffer is targeted.
3) A display history recording unit 11b provided in the application program 11 for associating and recording a timer (time storage / update means) connected to the I / O 4 and a page number designated by the user for display and the displayed time The page buffer storing the data of the page number associated with the oldest time is searched from existing page buffers, and the detected page buffer is targeted.
4) The display history recording unit 11b provided in the application program 11 has a function of storing the number of displayed times in association with each other, and the page number data associated with the smallest number of times of display is stored in the existing page buffer. The stored page buffer is searched, and the detected page buffer is targeted.
Etc.

Here, the page buffer 23 is designated as a drawing page, and the graphic accelerator 5 is made to draw the third page.
The graphic accelerator 5 reads the drawing command data prepared by the application program, and generates a raster image on the page buffer based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page. During this time, the display controller 6 remains displaying the page buffer 22.

  Next, in FIG. 4 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11a provided in the application program 11 designates the page buffer 23 as a display page, The third page is displayed on the display controller 6. At this time, the raster image in the page buffer 22 is stored as it is without being discarded.

  In FIG. 4 (4), when the user instructs a page return from the touch panel or the like via the I / O 4, the page management module 11a provided in the application program 11 displays the previous page in the page buffer being used. That is, a search is performed as to whether the second page is stored. If it is detected as a result of the search that the raster image of the second page is stored in the page buffer 22, the page buffer 22 is designated as a display page and the display controller 6 displays the second page. Usually, since the search is performed instantaneously, the user can read the previous page in an instant.

According to the above, if the page is already stored in the page buffer, the user can instantly call the page and read it again.
[Pattern 2]
FIG. 5 is a diagram showing a change in the state of the page buffer in the pattern 2.
In the pattern 2, as in the case of the pattern 1, a non-memory display body is used for the display 7, and the analyzing / shaping unit 11a, the image compressing unit 5a, and the image combining unit 6a are not used. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module.

  In FIG. 5A, the page buffer 21 stores the raster image of the first page that has already been viewed, and the page buffer 22 stores the raster image of the second page that is currently being viewed. The remaining areas are collectively managed by the page management module as free areas. The page management module 11c provided in the application program 11 designates the page buffer 22 as a display page and causes the display controller 6 to perform display. The display controller 6 continues to transfer the contents of the page buffer 22 to the display 7 at a constant cycle.

  Next, in FIG. 5 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 checks the remaining amount of free space, If there is sufficient capacity, a new page buffer is secured from the free space. In order to reduce fragmentation, it is desirable that the newly reserved page buffer is adjacent to the page buffer in use.

  If the remaining free space is insufficient, an appropriate page buffer is selected from the used page buffers, the page buffer is released, and a new page buffer is secured at the same location. For selecting an appropriate page buffer, the method used in the description of FIG. Note that only the usage of the page buffer may be changed without actually performing the release and reservation procedures.

  Then, the reserved page buffer 23 is designated as a drawing page, and the graphic accelerator 5 is made to draw the third page. The graphic accelerator 5 reads the drawing command data prepared by the application program 11 and generates a raster image on the page buffer based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page. During this time, the display controller 6 remains displaying the page buffer 22.

  Next, in FIG. 5 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 23 as a display page, The third page is displayed on the display controller 6. At this time, the raster image in the page buffer 22 is stored as it is without being discarded.

  Next, in FIG. 5 (4), when the user instructs page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 stores one page buffer in use. A search is performed to determine whether the previous page, that is, the second page is stored. If it is detected as a result of the search that the raster image of the second page is stored in the page buffer, the page buffer 22 is designated as the display page, and the display controller 6 displays the second page. Usually, since the search is performed instantaneously, the user can read the previous page in an instant.

According to the above, even when the user changes the size and number of page buffers, the page management module 11c can use the page buffer effectively. If the page is already stored in the page buffer, The user can instantly recall and read the page.
[Pattern 3]
FIG. 6 is a diagram showing a state change of the page buffer in the pattern 3.

Pattern 3 is an example in which a non-memory display body is used for the display 7, the analysis / shaping unit 11a is not used, and the image compression unit 5a and the image decoding unit 6a are used. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module 11c.
In FIG. 6A, the page buffer 21 is reserved in advance as a fixed area for the graphic accelerator 5 to interpret the rendering command data and render the raster image in the page buffer. Currently, all drawing is finished and it is empty. The page buffer 22 stores the compressed image of the first page that has already been browsed, and the page buffer 23 stores the compressed image of the second page that is currently being browsed. The remaining areas are collectively managed by the page management module as free areas. The page management module 11c provided in the application program 11 designates the page buffer 23 as a display page and causes the display controller 6 to perform display. The display controller 6 continues to transfer the contents of the page buffer 23 to the display 7 through the built-in image decoding unit 6a at a constant cycle.

  Next, in FIG. 6 (2), when the user instructs page feed from the touch panel or the like via the I / O 4, the page management module 11c provided in the application program 11 designates the page buffer 21 as a drawing page. Then, the graphic accelerator 5 is made to draw the third page. The graphic accelerator 5 reads the drawing command data prepared by the application program 11 and generates a raster image on the page buffer 21 based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page. During this time, the display controller 6 remains displaying the page buffer 23.

  Next, in FIG. 6 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 21 as a display page, The third page is displayed on the display controller 6. At this time, since the raster image is stored as it is in the page buffer 21 instead of the compressed image, the display controller 6 does not use the image decoding unit 6a. Here, it is possible to instruct the display controller 6 to display the compressed image after the compression work described later is completed, but in that case, there is a merit that the circuit configuration is slightly simplified. However, it is difficult to say that it is a good method because it takes a long time to start display.

  Next, the page management module 11c confirms whether there is enough free capacity remaining in the page buffer free area to store the page buffer after compression. Since the capacity actually required for the page buffer after compression cannot be determined that the compression is not completed, the confirmation is performed with the worst predicted value, that is, the maximum size. The maximum size depends on the compression technique used, but is usually the size of the raster image that is not compressed plus the size of some auxiliary information area.

  At this time, if the remaining amount of the free area is insufficient, one appropriate page buffer is selected from the used page buffers, and the page buffer is released to increase the free area. For selecting an appropriate page buffer, the method used in the description of FIG. In order to release the page buffer, it is necessary to perform fragmentation elimination processing which is an existing technique. That is, when a situation occurs in which a plurality of free areas of the page buffer remain in a fragmented manner, the used page buffer is moved to perform the work of combining the fragmented free areas into one.

Then, the page management module 11c provided in the application program 11 compresses the raster image in the page buffer 21 with respect to the image compression unit 5a provided in the graphic accelerator 5 and stores it from the top of the page buffer free area. To instruct.
Next, in FIG. 6 (4), when the image compression unit 5 a provided in the graphic accelerator 5 notifies the application program 11 that the compression work has been completed, the page management module 11 c provided in the application program 11. Acquires the compressed image size after compression from the image compression unit 5a, and reserves a new page buffer 24 from the head of the page buffer empty area with the size. Thereafter, the page buffer 24 is designated as a display page, and the third page is displayed on the display controller 6. The display controller 6 displays the contents of the page buffer 24 on the display 7 through the built-in image decoding unit 6a. Since the drawing process has been completed, the page management module 11c provided in the application program 11 sets the page buffer 21 to an empty state.

  Next, in FIG. 6 (5), when the user instructs the page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 stores the page buffer in use. A search is performed to determine whether the previous page, that is, the second page is stored. As a result of the search, when it is detected that the compressed image of the second page is stored in the page buffer 22, the page buffer 22 is designated as a display page and the display controller 6 displays the second page. Normally, the search is performed instantaneously from the viewpoint of the user, so that the user can read the previous page in an instant.

As described above, the page buffer memory area can be used more effectively by using the image compression / decoding means. At this time, since the display is started without waiting for the end of compression, the user can start reading the page to be read next quickly. In addition, if the page is already stored in the page buffer, the user can instantly call and read the page.
[Pattern 4]
FIG. 7 is a diagram showing a state change of the page buffer in the pattern 4.

Pattern 4 is an example in which a non-memory display body is used for the display, the image compression / decoding unit is not used, and the analysis / shaping unit 11a is used. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module 11c.
In FIG. 7A, the page buffer 21 and the page buffer 22 are used as fixed areas for the graphic accelerator 5 to interpret the rendering command data and render raster images in the page buffers 21 and 22, respectively. It is secured in advance as a fixed area for acquiring and displaying a raster image. The fixed area for drawing and the fixed area for display do not have fixed roles, but are changed as necessary.

  At present, the rendered raster image of the second page is stored in the page buffer 21 which is a fixed area for display, and is displayed by the display controller 6. All drawing processes have been completed, and the page buffer 22 which is a drawing fixed area is empty. The page buffer 23 stores the intermediate format of the first page that has already been laid out, and the page buffer 24 stores the intermediate format of the second page that has already been laid out. The remaining area is managed as a blank area by the page management module 11c.

  Next, in FIG. 7 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 stores one page in the page buffer empty area. Check if there is enough free space to store the intermediate format data. Since the capacity required for the intermediate format data for one page cannot be determined until the layout is completed, the value obtained experimentally and statistically is used. Here, using the property that the capacity of the intermediate format data is likely to be smaller than the capacity of the raster image, the size of the raster image for one page is the capacity required for the intermediate format data for one page. Judgment is considered.

  At this time, if the remaining free space is insufficient, an appropriate page buffer is selected from the used page buffers, and the page buffer is released to increase the free space. For selecting an appropriate page buffer, the method used in the description of FIG. In order to release the page buffer, it is necessary to perform fragmentation elimination processing which is an existing technique. That is, when a situation occurs in which a plurality of free areas in the page buffer remain in a fragmented manner, the page buffer being used is moved to perform the work of combining the fragmented free areas into one.

Next, the page management module 11c provided in the application program 11 reads the composite document data of the third page to the analysis / formatting unit 11a, performs layout processing (analysis and shaping), and executes the page buffer empty area. Instructs to write the intermediate format of the third page from the top.
At this time, if the drawing contents of the page are more complicated than expected, there is a possibility that the page buffer empty area is lost. In this case, the page management module 11c provided in the application program 11 performs the operation of releasing the used page buffer again to increase the free space, and re-executes layout processing to the analysis / shaping unit 11a. Instruct. If an intermediate format, which is the result of performing the layout process halfway, remains in the page buffer empty area, the process time can be shortened by restarting the layout from the continuation.

Next, in FIG. 7 (3), when the analysis / formatting unit 11a finishes the layout process, the page management module 11c provided in the application program 11 has the size of the intermediate format of the third page from the analysis / formatting unit 11a. And a page buffer 35 having the size is generated.
Next, the page management module 11c provided in the application program 11 designates the page buffer 22 as a drawing page, and causes the graphic accelerator 5 to draw the third page. The graphic accelerator 5 reads the intermediate format of the page buffer 35, that is, the drawing command data, and generates a raster image on the page buffer 22 based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page. During this time, the display controller 6 remains displaying the page buffer 21.

Next, in FIG. 7 (4), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 22 as a display page, The third page is displayed on the display controller 6.
Next, in FIG. 7 (5), when the user instructs the page return through I / O such as a touch panel, the page management module 11c provided in the application program 11 displays the previous display area in the display fixed area. A search is performed as to whether a page, that is, the second page is stored. If it is detected as a result of the search that the raster image of the second page is stored in the page buffer 21, the page buffer 21 is designated as a display page and the display controller 6 displays the second page. Normally, the search is performed instantaneously from the viewpoint of the user, so that the user can read the previous page in an instant.

  According to the above, since the intermediate format data having a smaller size than the raster image data or the compressed image data is stored in the page buffer, the page buffer memory area can be used more effectively. If the page is already stored in the page buffer, the user can call the page at high speed by performing only display or drawing and display without using the analysis / shaping unit 11a having a long processing time. Can be read. That is, it becomes possible to display compound document data by using the analyzing / shaping unit 11a, and at the same time, the influence of the analyzing / shaping unit 11a having a long processing time can be reduced.

Next, as an application example of the system, assuming a reading terminal adopting a memory display on the display 7, the user browses the second page of the document, then proceeds to the third page, and then reads the previous sentence. For confirmation, the state change of the page buffer will be specifically described for the case of returning to the second page again. Memory displays include electrophoretic displays, cholesteric liquid crystal displays, ferroelectric liquid crystal displays, toner displays, and twist ball displays. Once rewritten, the display content is retained even when the power is turned off. There is a feature that no renewal is required. Therefore, the display circuit need only transmit display data once.
[Pattern 5]
FIG. 8 is a diagram showing a state change of the page buffer in the pattern 5.

In the pattern 5, a memory-type display is used for the display, and the analysis / shaping unit 11a and the image compression / decoding unit are not used. In this example, the size of the page buffer per page is equivalent to the storage capacity of the display, and the number of pages is fixed to 4 by a value determined at the time of system design or by a setting change program.
In FIG. 8A, the page buffer 21 stores the raster image of the first page that has already been viewed, and the page buffer 22 stores the raster image of the second page that is currently being viewed. Yes. The page buffers 23 and 24 are free. The display operation of the page buffer 22 (second page) by the display controller 6 (hereinafter referred to as writing) has already been completed, and the display controller 6 is in a standby state.

Next, in FIG. 8 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 is in an empty state from the page buffer. Search for things and use the detected page buffer as a new drawing page.
If there is no remaining page buffer, an appropriate page buffer is selected from the page buffers in use, and the page buffer is regarded as a free page buffer and used as a new drawing page buffer. For selecting an appropriate page buffer, the method used in the description of FIG. 4B can be used.

  Here, the page buffer 23 is designated as the drawing page, and the graphic accelerator 5 is caused to draw the third page. The graphic accelerator 5 reads the drawing command data prepared by the application program 11 and generates a raster image on the page buffer based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page.

  Next, in FIG. 8 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 23 as a display page, The display controller 6 is made to write the third page. At this time, the contents of the page buffer 22 are stored as they are without being discarded.

  Next, in FIG. 8 (4), when the user instructs a page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 moves the previous page buffer into use. A search is performed as to whether the second page, that is, the second page is stored. If it is detected as a result of the search that the raster image of the second page is stored in the page buffer 22, the page buffer 22 is designated as a display page, and the display controller 6 writes the second page. Usually, since the search is performed instantaneously, the user can read the previous page quickly.

According to the above, if the page is already stored in the page buffer, the user can quickly call and read the page.
[Pattern 6]
FIG. 9 is a diagram showing a state change of the page buffer in the pattern 6.
In the pattern 6, a memory-type display is used for the display, and the analysis / shaping unit 11a and the image compression / decoding unit are not used. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module 11c.

  In FIG. 9A, the page buffer 21 stores the raster image of the first page that has already been browsed, and the page buffer 22 stores the raster image of the second page that is currently being browsed. . The remaining areas are collectively managed by the page management module 11c as free areas. The writing of the page buffer 22 (second page) by the display controller 6 has already been completed, and the display controller 6 is in a standby state.

  Next, in FIG. 9 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 checks the remaining amount of free space, If there is sufficient capacity, a new page buffer is secured from the free space. In order to reduce fragmentation, it is desirable that the newly reserved page buffer is adjacent to the page buffer in use.

  At this time, if the remaining free space is insufficient, an appropriate page buffer is selected from the currently used page buffers, the page buffer is released, and a new page buffer is secured at the same location. . For selecting an appropriate page buffer, the method used in the description of FIG. 4B can be used. Note that only the usage of the page buffer may be changed without actually performing the release and reservation procedures.

  Then, the reserved page buffer 23 is designated as a drawing page, and the graphic accelerator 5 is made to draw the third page. The graphic accelerator 5 reads drawing command data prepared by the application program, and generates a raster image on the page buffer 23 based on the read drawing command data. Usually, a certain time, for example, about 1 second is required for the graphic accelerator 5 to draw one page.

  Next, in FIG. 9 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has been completed, the page management module 11c provided in the application program 11 designates the page buffer 23 as a display page, The display controller 6 is made to write the third page. At this time, the contents of the page buffer 22 are stored as they are without being discarded.

  Next, in FIG. 9 (4), when the user instructs a page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 immediately before the page buffer being used. A search is performed as to whether the second page, that is, the second page is stored. If it is detected as a result of the search that the raster image of the second page is stored in the page buffer 2, the page buffer 22 is designated as the display page, and the display controller 6 is made to write the second page. Usually, since the search is performed instantaneously, the user can read the previous page quickly.

According to the above, even when the user changes the size and number of page buffers, the page management module 11c can use the page buffer effectively. If the page is already stored in the page buffer, The user can quickly call up and read the page.
[Pattern 7]
FIG. 10 is a diagram showing a state change of the page buffer in the pattern 7.

Pattern 7 is an example in which a memory-type display is used for the display and the image compression / decoding means is used without using the analysis / shaping unit 11a. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module 11c.
In FIG. 10A, the page buffer 21 is secured in advance as a fixed area for the graphic accelerator 5 to interpret the rendering command data and render a raster image in the page buffer. At the moment, all drawing is finished and it is empty. The page buffer 22 stores the compressed image of the first page that has already been browsed, and the page buffer 23 stores the compressed image of the second page that is currently being browsed. The remaining areas are collectively managed by the page management module 11c as free areas. The writing of the page buffer 23 (second page) by the display controller 6 has already been completed, and the display controller 6 is in a standby state.

  Next, in FIG. 10 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 sets the page buffer 21 to the drawing page. The graphic accelerator 5 is designated and the third page is drawn. The graphic accelerator 5 reads the drawing command data prepared by the application program, and generates a raster image on the page buffer 21 based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page.

  Next, in FIG. 10 (3), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 21 as a display page. Then, the third page is written in the display controller 6. At this time, since the raster image is stored as it is in the page buffer 21 instead of the compressed image, the display controller 6 does not use the image decoding unit 6a. Here, it is possible to configure the display controller 6 to write a compressed image after the compression work described later is completed, but in that case, although there is a merit that the circuit configuration is slightly simplified, Since there is a drawback that the time until the display starts becomes long, it is not preferable.

  Next, the page management module checks whether there is enough free capacity remaining in the page buffer empty area to store the page buffer after compression. Since the capacity actually required for the page buffer after compression cannot be determined that the compression is not completed, the confirmation is performed with the worst predicted value, that is, the maximum size. The maximum size depends on the compression technique used, but is usually the size of the raster image that is not compressed plus the size of some auxiliary information area.

  At this time, if the remaining free space is insufficient, an appropriate page buffer is selected from the used page buffers, and the page buffer is released to increase the free space. For selecting an appropriate page buffer, the method used in the description of FIG. In order to release the page buffer, it is necessary to perform fragmentation elimination processing which is an existing technique. That is, when a situation occurs in which a plurality of free areas in the page buffer remain in a fragmented manner, the used page buffer is moved to perform the work of combining the fragmented free areas into one.

Then, the page management module 11c provided in the application program 11 compresses the raster image in the page buffer 1 to the image compression unit 5a provided in the graphic accelerator 6 and stores it from the top of the page buffer empty area. To instruct.
Next, in FIG. 10 (4), when the image compression unit 5a provided in the graphic accelerator 6 notifies the application program 11 that the compression work has been completed, the page management module 11c provided in the application program 11 The compressed image size after compression is acquired from the image compression unit 5a, and a new page buffer 24 is secured from the top of the page buffer empty area according to the size. If writing by the display controller 6 is not performed in the step of FIG. 10 (3), the page buffer 24 is designated as a display page, and the third page is written to the display controller 6. The display controller 6 writes the contents of the page buffer 24 into the display 7 through the built-in image decoding unit 6a. Since the drawing process has been completed, the page management module 11c provided in the application program 11 sets the page buffer 21 to an empty state.

  Next, in FIG. 10 (5), when the user instructs page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 moves the previous page buffer into use. A search is performed as to whether the second page, that is, the second page is stored. If it is detected as a result of the search that the compressed image of the second page is stored in the page buffer 22, the page buffer 22 is designated as a display page, and the display controller 6 writes the second page. Normally, a search is performed instantaneously from the viewpoint of the user, so that the user can quickly read the previous page.

As described above, the page buffer memory area can be used more effectively by using the image compression / decoding means. At this time, since the display is started without waiting for the end of compression, the user can start reading the page to be read next quickly. If the page is already stored in the page buffer, the user can quickly call and read the page.
[Pattern 8]
FIG. 11 is a diagram showing a state change of the page buffer in the pattern 8.

Pattern 8 is an example in which a memory-type display is used for the display, the image compression / decoding unit is not used, and the analysis / shaping unit 11a is used. The size of the page buffer per page and the number of page buffers are dynamically managed by the page management module.
In FIG. 11A, the page buffer 21 is a fixed area for the graphic accelerator 5 to interpret the rendering command data and render the raster image in the page buffer, and the display controller 6 acquires and displays the raster image. As a fixed area for this purpose, it is secured in advance. The roles of the fixed area for drawing and the national area for display are not fixed, but are changed as necessary.

  At this time, the display operation by the display controller 6 has already been completed, and the display controller 6 is in a standby state. In addition, the drawing process is also completed, and the graphic accelerator 5 is in a standby state. The page buffer 21, which is a drawing fixed area, is empty. The page buffer 22 stores the intermediate format of the first page that has already been laid out, and the page buffer 23 stores the intermediate format of the second page that has already been laid out. The remaining areas are collectively managed by the page management module 11c as free areas.

  Next, in FIG. 11 (2), when the user instructs page feed via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 stores one page in the page buffer empty area. Check if there is enough free space left to store the intermediate format data. Since the capacity required for the intermediate format data for one page cannot be determined until the layout is completed, the value obtained experimentally and statistically is used. Here, using the property that the capacity of the intermediate format data is likely to be smaller than the capacity of the raster image, the size of the raster image for one page is the capacity required for the intermediate format data for one page. Judgment is considered.

  At this time, if the remaining free space is insufficient, an appropriate page buffer is selected from the used page buffers, and the page buffer is released to increase the free space. For selecting an appropriate page buffer, the method used in the description of FIG. In order to release the page buffer, it is necessary to perform fragmentation elimination processing which is an existing technique. That is, when a situation occurs in which a plurality of free areas in the page buffer remain in a fragmented manner, the used page buffer is moved to perform the work of combining the fragmented free areas into one.

Next, the page management module 11c provided in the application program 11 reads the composite document data of the third page to the analysis / formatting unit 11a, performs layout processing (analysis and shaping), and executes the page buffer empty area. Instructs to write the intermediate format of the third page from the top.
At this time, if the drawing contents of the page are more complicated than expected, there is a possibility that the page buffer empty area is lost. In that case, the page management module 11c provided in the application program 11 executes means for releasing the page buffer being used again to increase the free space, and re-executes the layout processing to the analysis / shaping unit 11a. Instruct. If an intermediate format, which is the result of performing the layout process partway through, remains in the page buffer empty area, the processing time can be expected to be shortened by restarting the layout from there.

Next, in FIG. 11 (3), when the analysis / formatting unit 11a finishes the layout process, the page management module 11c provided in the application program 11 has the size of the intermediate format of the third page from the analysis / formatting unit 11a. And a page buffer 24 having the size is generated.
Next, the page management module 11c provided in the application program 11 designates the page buffer 21 as a drawing page, and causes the graphic accelerator 5 to draw the third page. The graphic accelerator 5 reads the intermediate format of the page buffer 24, that is, the drawing command data, and generates a raster image on the page buffer 21 based on the read drawing command data. Usually, it takes a certain time, for example, about 1 second for the graphic accelerator 5 to draw one page. During this time, the display controller 6 remains in a standby state.

Next, in FIG. 11 (4), when the application program 11 is notified that the drawing of the graphic accelerator 5 has ended, the page management module 11c provided in the application program 11 designates the page buffer 21 as a display page. Then, the third page is written in the display controller 6.
Next, in FIG. 11 (5), when the user instructs a page return via the I / O 4 from the touch panel or the like, the page management module 11c provided in the application program 11 has the previous page buffer stored therein. A search is performed as to whether a page, that is, the second page is stored. As a result of the search, when it is detected that the intermediate format of the second page is stored in the page buffer 23, the page buffer 21 which is a fixed area for drawing is designated as the drawing page, and the page buffer 23 is sent to the graphic accelerator 5. Is instructed to draw the second page.

Next, in FIG. 11 (6), when the application program 11 is notified that the drawing of the graphic accelerator 5 has been completed, the page management module 11c provided in the application program designates the page buffer 21 as a display page, and the display The controller 6 is made to write the second page.
According to the above, since the intermediate format data having a smaller size than the raster image data or the compressed image data is stored in the page buffer, the page buffer memory area can be used more effectively. If the page is already stored in the page buffer, the user can call the page at high speed by performing only display or drawing and display without using the analysis / shaping unit 11a having a long processing time. Can be read. That is, it becomes possible to display compound document data by using the analyzing / shaping unit 11a, and at the same time, the influence of the analyzing / shaping unit 11a having a long processing time can be reduced.
(Second Embodiment)
The hardware configuration, software configuration, and memory configuration in the present embodiment are the same as those in the first embodiment. The difference between the present embodiment and the first embodiment is as follows.

FIG. 12 is a diagram showing a memory configuration (memory map) in the second embodiment.
As shown in FIG. 12, in addition to part or all of the system program 10 and the application program 11, a heap area 25 and page buffers 21, 22, 23, and 24 are mapped in the RAM 3. The memory management module 10a incorporated in the system program 10 manages all memory areas including the page buffer area. The page management module 11c incorporated in the application program requests the memory management module 10a to acquire the memory area (page buffer area) managed by the page management module 11c from the memory area managed by the memory management module 10a. . The page management module 11c normally secures a plurality of page buffers in the page buffer area. Of course, there may be a memory area that is not managed by either the memory management module 10a or the page management module 11c.

In the present embodiment, all the operations described in the first embodiment are possible. In addition, the following operations are possible.
[Page buffer decrease operation]
FIG. 13 is a diagram showing the flow of the page buffer decreasing operation.
As shown in FIG. 13, as a result of the system program 10 or the application program 11 allocating memory from the heap area, the free area of the heap area decreases and the remaining amount is a constant value (for example, 256 kilobytes). Below the threshold, the heap area management module incorporated in the memory management module 10a transmits a message indicating insufficient free space to the page management module 11c (A1). The communication method among the memory management module 10a, heap area management module, and page management module 11c uses existing technology. There are various methods in the existing technology, and not only the method of sending a message but also a method of passing it as a return value of a function call or changing a value of a shared variable or shared memory space.

The page management module 11c that has received a message indicating insufficient free space requests the memory management module 10a to partially release the memory in order to release a certain amount of memory (for example, 256 kilobytes) from the second half of the page buffer free space. (A2).
At this time, if there is not enough free space in the page buffer area to release the memory, the page management module releases the page buffer according to the procedure described in FIG. To increase the page buffer free space.

  When the memory management module 10a succeeds in releasing part of the page buffer free area and sends a message indicating that the memory release is successful to the page management module 11c (A3), the page management module 11c can secure the memory. A message indicating that it has become is transmitted to the heap area management module incorporated in the memory management module 10a (A4).

The heap area management module incorporated in the memory management module 10a receives the memory reservation possible message and requests the memory management module 10a to additionally secure a certain amount of memory (for example, 256 kilobytes) (A5).
The memory management module 10a secures addition of the requested memory, and sends a message indicating that the securing is successful to the heap area management module (A6).

The heap area management module receives the secure success message, adds the secured memory space to the latter half of the free area of the heap area, increases the free area, and prepares for a subsequent heap memory reservation request.
[Page buffer increase operation]
FIG. 14 is a diagram showing the flow of the page buffer increasing operation.

  As shown in FIG. 14, as a result of the system program 10 or the application program 11 releasing the memory used in the heap area 25, the free area 27 in the heap area 25 is increased, and the remaining amount is reduced. When the value exceeds a certain value (for example, 512 kilobytes), the heap area management module incorporated in the memory management module 10a gives the memory management module 10a a certain amount of memory (for example, 256 kilobytes) from the free area 27 of the heap area 25. A message requesting to release a part of the message is sent (B1).

When the memory management module 10a succeeds in partially releasing the memory, the memory management module 10a transmits a message indicating the success of the partial release to the heap area management module (B2).
The heap area management module receives a message indicating that the partial release has succeeded and transmits a message indicating that the memory can be secured to the page management module 11c (B3).
The page management module 11c receives the memory reservation possible message and requests the memory management module 10a to additionally secure a certain amount of memory (for example, 256 kilobytes) (B4).

When the memory management module 10a succeeds in securing the addition of the memory, the memory management module 10a transmits a message indicating the success of securing the addition to the page management module 11c (B5).
The page management module 11c receives the message indicating the successful addition reservation, adds the added memory to the page buffer free area, increases the free area, and prepares for a subsequent page buffer reservation request.

According to the above configuration, a limited memory space can be efficiently used interchangeably between the system program 10, the application program 11, and the page buffer. In other words, the surplus memory is automatically used for the page buffer, so that high-speed display is possible without any special setting.
In this embodiment, a fixed amount of memory is handled as 256 kilobytes and 512 kilobytes, but is not limited to these values, and can be set to any value. At this time, it is desirable to determine the maximum amount when the system program 10 or the application program 11 dynamically secures or releases the memory. In the present embodiment, for example, the application program 11 has a specification that can handle compressed image data (JPEG, GIF, etc.) of a maximum of 128 kilobytes, and has a structure that dynamically secures a reception buffer on the heap. This is the best example.

As described above, the present invention has been described in each embodiment. However, the configuration and the like of the invention are not limited to these embodiments. For example, the following variations are possible.
<Configuration variations>
The page management module may be integrated with the memory management module. The page management module may be incorporated in the system program. The page management module may be incorporated in the application program. The memory management module may be incorporated in the system program. The memory management module may be incorporated in the application program. The image compression unit may be integrated with the drawing unit. The image compression unit may be incorporated in the system program. Further, the image compression unit may be incorporated in an application program. The image decoding unit may be integrated with the drawing unit. The image decoding unit may be integrated with the display unit. Further, the image decoding unit may be incorporated in the system program. Further, the image decoding unit may be incorporated in the application program. The analysis / shaping unit may be incorporated in the system program. The analysis / shaping unit may be incorporated in the application program. Further, the display history recording unit may be integrated with the page management module. The display history recording unit may be incorporated in the system program. Further, the display history recording unit may be incorporated in the application program. In order to improve the performance of the page management module, a dedicated storage device may be provided inside the page management module, or a dedicated storage device for the page management module may be provided outside the page management module. In order to improve the performance of the memory management module, a dedicated storage device may be provided inside the memory management module, or a storage device dedicated to the memory management module may be provided outside the memory management module. Further, in order to improve the performance of the image compression unit, a dedicated storage device may be provided inside the image compression unit, or a storage device dedicated to the face compression means may be provided outside the image compression unit. In order to improve the performance of the image decoding unit, a dedicated storage device may be provided inside the image decoding unit, or a storage device dedicated to the image decoding unit may be provided outside the image decoding unit. Further, in order to improve the performance of the analysis / shaping unit, a dedicated storage device may be provided inside the analysis / shaping unit, or a storage device dedicated to the analysis / shaping unit may be provided outside the analysis / shaping unit. In order to improve the performance of the display history recording unit, a dedicated storage device may be provided inside the display history recording unit, or a storage device dedicated to the display history recording unit may be provided outside the display history recording unit. Further, in order to improve the performance of the drawing unit, a dedicated storage device may be provided inside the drawing unit, or a storage device dedicated to the drawing unit may be provided outside the drawing unit. In order to improve the performance of the display unit, a dedicated storage device may be provided inside the display unit, or a dedicated storage device may be provided outside the display unit. The drawing unit and the display unit may be integrated.

  The present invention can be applied in various ways as long as it is a display device or a display program for displaying a document having the concept of pages. Particularly, in a display device that displays compound document data including layout information, the present invention is effective because a large amount of processing time is required for layout. For example, in personal computers and personal data assistants with built-in Internet browsers, network computers, electronic books, set-top boxes, other display devices adopting an XML-based data format, and computer programs installed in the above devices Applicable.

It is the figure which showed the hardware constitutions of the information display apparatus in the 1st Embodiment of this invention. It is the figure which showed the software structure of the information display apparatus in the 1st Embodiment of this invention. It is the figure which showed the memory structure of the information display apparatus in the 1st Embodiment of this invention. FIG. 6 is a diagram showing a state change of a page buffer in pattern 1. FIG. 10 is a diagram showing a state change of a page buffer in pattern 2. FIG. 10 is a diagram showing a state change of a page buffer in pattern 3. FIG. 10 is a diagram showing a state change of a page buffer in pattern 4. FIG. 10 is a diagram showing a state change of a page buffer in pattern 5. FIG. 10 is a diagram showing a state change of a page buffer in pattern 6. FIG. 9 is a diagram showing a state change of a page buffer in pattern 7. FIG. 10 is a diagram showing a state change of a page buffer in pattern 8. It is the figure which showed the memory structure (memory map) in 2nd Embodiment. It is the figure which showed the flow of the page buffer reduction operation. It is the figure which showed the flow of the page buffer increase operation.

Explanation of symbols

1 CPU, 2 ROM, 3 storage device (RAM), 4 I / O, 5 drawing unit (graphic accelerator), 5a image compression unit, 6 display unit (display controller), 6a image decoding unit, 7 display, 8 bus, 10 system program (OS), 10a memory management module (storage device management means), 11 application program, 11a analysis / shaping unit, 11b display history recording unit, 11c page management module, 21, 22, 23, 24 page buffer, 25 Heap area, 26 used area, 27 free area

Claims (17)

A memory capable of storing display data to be displayed, writing means for writing the display data in a predetermined area in the memory, and reading the display data written in the predetermined area for each page as a display unit A display control means for displaying on the display; and a memory management means for performing memory management corresponding to a memory management function of the operating system. A heap area is formed in a system area secured on the memory by the memory management means. An information display device that performs processing,
Page buffer management means for securing a dedicated area for storing the display data outside the system area on the memory, and forming a page buffer which is a storage area for the display data for each page in the dedicated area; Including
The writing means and the display control means are configured to be accessible to the dedicated area,
The writing means writes the display data to a predetermined page buffer in the dedicated area;
The information display device, wherein the display control means reads the display data written in a predetermined page buffer in the dedicated area and displays it on the display.   The information display apparatus according to claim 1, wherein the memory management unit is capable of managing the dedicated area.   3. The information display device according to claim 1, wherein the system area is secured from an upper address side in the memory, and the dedicated area is secured from a lower address side in the memory.   4. The information display device according to claim 1, wherein a capacity of the page buffer is a fixed value corresponding to a data amount of a rasterized image for one page of the display data. 5. Compression means for compressing the display data to be written by the writing means by a predetermined compression method;
Decoding means for decoding the compressed display data to be read by the display control means;
The information display device according to claim 1, further comprising: Analyzing / shaping means for generating intermediate format data obtained by performing document structure analysis and layout processing for the display data to be written by the writing means;
Conversion means for converting the intermediate format data to be read by the display control means into a rasterized image;
The information display device according to claim 1, further comprising:   7. The information display device according to claim 5, wherein the page buffer has a capacity that can be changed in accordance with a data amount of the display data written by the writing means.   8. The information display device according to claim 1, wherein each of the system area and the dedicated area is secured in a fixed address range.   2. The page buffer management unit and the memory management unit are capable of mutually changing the sizes of the system area and the dedicated area in accordance with usage states of the system area and the dedicated area. 8. The information display device according to any one of 7 to 7.   9. The size of the heap area and the dedicated area can be changed from each other based on the capacity of a free area in the heap area in the system area. Information display device.   11. The information display according to claim 1, wherein when the page buffer is released, the page buffer management unit releases the page buffer located at an address closer to the heap area. apparatus.   When the page buffer management unit releases the page buffer, the page buffer management unit stores the page buffer in which display data having a page number farther from the page number of the display data read by the display control unit is stored. The information display device according to claim 1, wherein the information display device is released. The display data stored in the page buffer further comprises display order storage means for storing the order displayed on the display,
When releasing the page buffer, the page buffer management unit releases the page buffer in which display data displayed in an earlier order is stored based on the order stored in the display order storage unit. The information display device according to claim 1, wherein the information display device is an information display device. The display data stored in the page buffer further includes display time storage means for storing the time displayed on the display,
When the page buffer is released, the page buffer management unit releases the page buffer in which display data displayed at an earlier time is stored based on the time stored in the display time storage unit. The information display device according to claim 1, wherein the information display device is an information display device. The display data stored in the page buffer further includes a display number storage means for storing the number of times displayed on the display,
When the page buffer management unit releases the page buffer, the page buffer management unit releases the page buffer in which display data having a smaller number of times of display is stored based on the number of times stored in the display number storage unit. The information display device according to claim 1, wherein the information display device is an information display device. A memory capable of storing display data to be displayed, writing means for writing the display data in a predetermined area in the memory, and reading the display data written in the predetermined area for each page as a display unit A display control means for displaying on the display; and a memory management means for performing memory management corresponding to a memory management function of the operating system. A heap area is formed in a system area secured on the memory by the memory management means. A method for controlling an information display device that performs processing,
Reserve a dedicated area for storing the display data outside the system area on the memory,
In the dedicated area, a page buffer that is a storage area of display data for each page is formed,
Write the display data to a predetermined page buffer in the dedicated area,
A control method for an information display device, comprising: reading the display data written in a predetermined page buffer in the dedicated area and displaying the read data on the display. A memory capable of storing display data to be displayed, writing means for writing the display data in a predetermined area in the memory, and reading the display data written in the predetermined area for each page as a display unit A display control means for displaying on the display; and a memory management means for performing memory management corresponding to a memory management function of the operating system. A heap area is formed in a system area secured on the memory by the memory management means. An information display program for controlling an information display device that performs processing,
The information display device is configured such that the writing unit and the display control unit can access the dedicated area,
Realizes a page buffer management function that secures a dedicated area for storing the display data outside the system area on the memory, and forms a page buffer as a display data storage area for each page in the dedicated area. Let
An information display program that enables writing of the display data by the writing means and reading of the display data by the display control means in a predetermined page buffer in the dedicated area.

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