JPH0728441A - Method for displaying picture - Google Patents

Abstract

PURPOSE:To perform high-speed display process even when many files are developped on a memory by saving a storage area of a main memory. CONSTITUTION:The picture data are written in the VRAM area of the main memory RAM as a buffer area, and the compressed data encoded according to a data redundant component incorporated in the buffer area are stored in a storage means excepting the main RAM 1c as a compressed file. Since after the compressed data are read out from the compressed file, are decoded to the picture data in the buffer area, the storage area of the main memory 1c is saved, and thus, the high-speed display process is performed even when many files are developped on the main memory 1c.

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a screen display method suitable for use in, for example, a portable computer called a "handy terminal".

[0002]

2. Description of the Related Art In recent years, various portable computers called "handy terminals" have been put into practical use. This type of computer is portable and
It is used in various fields because it enables various data processing at the carrying destination. FIG. 7 is a block diagram showing a configuration example of such a handy terminal 1.

In FIG. 7, reference numeral 1a is a CPU for controlling each part of the handy terminal 1. 1b is the CPU 1a
An operating system program (hereinafter, abbreviated as OS) that controls the basic operation of the RO is stored
It is M. Reference numeral 1c is a RAM in which an application program for the corresponding business is loaded and various register values are temporarily stored as a work area of the program. Reference numeral 1d is a display circuit composed of an LCD (liquid crystal display element) or the like, and displays various data supplied from the CPU 1a via an internal bus. Reference numeral 1e is an operator including a touch panel provided on the LCD (liquid crystal display element), a numeric keypad and a function key for inputting numbers arranged on the main body panel, and operator signals corresponding to respective operations. To occur.

Reference numeral 1f is a memory card detachably attached to the main body. The memory card 1f stores the above-mentioned application program or various data referred to by the program. If this memory card 1f is not attached to the main body,
It is also possible to use part of the RAM 1c described above as a RAM disk and store application programs and various data therein. The data stored in the memory card 1f is downloaded from a host computer (not shown). Reference numeral 1g is a communication control circuit which is composed of, for example, a modem and controls serial data communication. The handy terminal 1 having such a configuration operates as a known personal computer. That is, after the power is turned on, the OS starts up, the application program for the corresponding work is started on the OS, and various data processes are executed.

Since the handy terminal 1 is formed in a small size so that it can be carried, it is often a touch input mode in which various input screens are displayed on a liquid crystal touch panel. In order to display the input screen on the liquid crystal touch panel, the CPU 1a reads the corresponding screen data from the ROM 1b and temporarily stores it in the RAM 1c as a file. Next, the screen data stored in this file is expanded in a video RAM (hereinafter abbreviated as VRAM) area. Thus, once the input screen is displayed,
In the subsequent display, the screen data stored in the file is directly expanded in the VRAM area to speed up the display processing.

[0006]

However, in the above-described screen display method, if the storage capacity of the RAM 1c is limited, the display processing may not be speeded up. For example, when an application program that expands a large number of files on the RAM 1c is activated, the storage area of the RAM 1c becomes insufficient and screen data may not be stored in a file. In such a case, the screen data cannot be allocated to the VRAM area inevitably, and the display processing cannot be speeded up. Therefore, under such circumstances, the speed of display processing is sacrificed, and the application program side generates screen data and displays the input screen.

By the way, in recent years, various file compression / decompression techniques have been developed, and it has been proposed to apply this file compression / decompression technique to the above-mentioned screen display method. That is, the screen data is compressed and stored in the RAM 1c as a compressed file. When the input screen is displayed, the compressed file is decompressed and stored in the decompressed file. After that, the content of the decompressed file is VRA.
It is developed in the M area.

However, in this file compression / decompression process, although the compression process apparently reduces the data capacity of the screen data, a decompression file having the same data capacity as before compression is allocated on the RAM 1c after decompression. Therefore, even if the file compression / decompression processing is performed, when many files are expanded on the RAM 1c, the storage area of the RAM 1c is insufficient as in the conventional case, and as a result, the display processing cannot be speeded up. There is a harmful effect. In other words, the conventional screen display method cannot save the storage area of the main memory and cannot display the screen at high speed when many files are expanded in the main memory. ing.
The present invention has been made in view of the above circumstances, and provides a screen display method that saves the storage area of the main memory and can perform high-speed display processing even if many files are expanded in the memory. It is an object.

[0009]

SUMMARY OF THE INVENTION The present invention provides a screen display method for expanding screen data stored in a file storage area of a main memory into an image storage area inside the main memory and displaying the screen on the screen. A first step of setting an address to a buffer area, writing the screen data in the buffer area, and detecting a redundant data component contained in the buffer area, and compressing the compressed data to be encoded according to the detection result. A second step of storing in the file storage area, wherein the compressed data is decoded into the screen data in the buffer area.

[0010]

According to the present invention, screen data is written using the image storage area inside the main memory as a buffer area, and compressed data encoded according to the data redundant component contained in the buffer area is stored in the main memory as a file. Store in the area. This compressed data is decoded into screen data in the buffer area. As a result, the storage area of the main memory is saved, so that high-speed display processing is possible even when many files are expanded on the main memory.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A screen display method according to an embodiment of the present invention will be described below with reference to the drawings. Note that this embodiment is applied to the handy terminal 1 having the configuration shown in FIG. 7, for example, and is realized by the compression / decompression processing (described later) executed by the CPU 1a (see FIG. 7).

That is, according to the present invention, the screen data is stored in the compressed file, and the compressed file is stored in the VRAM.
Decompress in the area, and decompress screen data in VRAM
The data is expanded into an area to save the consumption of the main memory (RAM1c). As a result, even when many files are expanded in the main memory (RAM 1c), the screen data can be directly allocated to the VRAM area, which enables high-speed display processing. The operation of such compression / decompression processing will be described below with reference to FIGS. The compression / decompression process is performed based on, for example, a compression (encoding) / decompression (decoding) algorithm based on the well-known Lempel-Ziv code (slide dictionary method).

Operation of the compression process First, when the handy terminal 1 is powered on, R
The operating system program read from the OM 1b is booted up. In this state, if a command to compress the screen data is input, CP
U1a activates the compression program shown in FIG. As a result, the processing of the CPU 1a proceeds to step Sa1. The screen data is information displayed on the liquid crystal touch panel of the handy terminal 1. First, in step Sa1, initial settings are made with the VRAM area as the buffer area. In this initial setting, as shown in FIG. 2, the VRAM area is set to the reference area CR and the compression target area CE.
And are addressed to have a predetermined buffer length.

In the reference area CR, the start address of the VRAM area corresponds to the reference area start address CRA. Further, in the compression target area CE, the reference area start address CR
An address separated from A by a predetermined buffer area becomes a compression target area start address CEA. When the address of the VRAM area is set in this way, the CPU 1a reads a part of the screen data stored in the ROM 1b and writes it in the VRAM area. That is, the VRAM area is regarded as a temporary file for compression work. The data in the reference area CR in the initial state is all written in a compressed file described below in an uncompressed format.

When part of the screen data is stored in the VRAM area in this way, the processing of the CPU 1a proceeds to the next step Sa.
Go to 2. In step Sa2, the reference area CR is searched for data that matches the leading data of the compression target area CE. If there is matching data in the reference area CR, the determination result of step Sa3 becomes "YES", and the processing of the CPU 1a proceeds to step Sa4.

In step Sa4, the address pointers corresponding to the search target data in the compression target area CE and the reference area CR are sequentially stepped, and the data matching the search target data is searched to find the data in the compression target area CE. The longest matching data is detected by comparing the data string with the data string in the reference area CR. As a result, the CPU 1a
The address position of the first matched data and the number of matched data are recorded in the reference area CR. Next, when proceeding to step Sa5, the compression target area CE is determined according to the search result.
The data of is encoded.

In this encoding, for example, the number of data that matches the address position of the matching data in the reference area CR is set as a code word, and a matching bit "1" is added to the head of this code word. Further, when the result of the determination in step Sa3 described above is “NO”, that is, when there is no data that matches the compression target area CE, for example, a mismatch bit “0” is added to the leading data of the compression target area CE. Is added and encoded. Then, when the operation proceeds to step Sa6, this encoded compressed data is written in the compressed file. The compressed file is secured in a predetermined area of the RAM 1c.

Next, in step Sa7, as shown in FIG. 3, the reference area start address CRA and the compression target area start address CEA are slid (shifted) by the encoded data amount. Next, in step Sa8, the CPU 1a determines whether or not the slid compression target area start address CEA has reached the final address of the VRAM area.

Here, the compression target area start address CEA
Is the same as the final address of the VRAM area, V
It is considered that the compression of the screen data taken into the RAM area is completed, and this compression processing is completed. On the other hand, if the final address has not been reached, the process returns to step Sa2 to repeat the above process and continue the compression process. The compression operation described above compresses part of the screen data written in the VRAM area. Therefore, in order to compress the full screen data, steps Sa1 to Sa described above are required.
8 will be repeated several times.

According to the above-described compression processing, the VRAM area is used as a buffer when encoding by the Lempel-Ziv code (slide dictionary method), and the screen data compressed by this encoding is stored in the RAM 1c as a compressed file. Is stored. Therefore, RA
It becomes possible to save the storage capacity of the M1c. Also,
In the compression process, since the screen data expanded in the VRAM area is directly compressed and stored in the compressed file, a temporary file is not created unlike the conventional case, and access to the file is unnecessary, which is efficient. The compression process is realized. In this compression process, if the screen data forms a screen with many white parts and black parts when it is displayed on a monochrome liquid crystal, the compression rate is further improved due to the nature of the compression algorithm.

Operation of decompression processing In the state where the above compression processing program is completed,
When a command is input to start the decompression process, C
In response to this, the PU 1a activates the decompression processing program shown in FIG. 2 and advances the processing to step Sb1. Step S
In b1, similarly to the above-described compression processing, the VRAM area is used as the buffer area for initial setting. In this initial setting, as shown in FIG. 5, the VRAM area is set to the reference area F.
R and the decompressed data expansion area FE are addressed so as to have a predetermined buffer length.

In the reference area FR, the start address of the VRAM area corresponds to the reference area start address FRA. Further, in the compression target area FE, the reference area start address FR
An address separated by a predetermined buffer length from is the compression target area start address FEA. When the address of the VRAM area is set, the processing of the CPU 1a proceeds to step Sb2 to read the encoded screen data from the compressed file and store it in the reference area FR. in this case,
The contents of the reference area FR are the same as the reference area CR at the time of the compression processing described above.

When the compressed file is read, C
The process of PU1a proceeds to the next step Sb3. In step Sb3, the compressed data is sequentially read from the beginning of the reference area FR and decoded. That is, if the mismatched bit “0” is added to the beginning of the read compressed data, the data after the mismatched bit “0” is directly decoded and output. On the other hand, in the case where the matching bit “1” is added to the beginning of the compressed data, the reference area FR is determined based on the address position and the number of matching data included in the code word.
Copy the data of.

When the data in the reference area FR is thus decoded, the CPU 1a proceeds to step Sb4 to write the decoded screen data in order from the start address of the decompressed data expansion area FE. Next, when proceeding to step Sb5, as shown in FIG. 6, the reference data start address FRA and the decompressed data expansion start address F for the decoded data amount.
The EA is slid (shifted), and the process proceeds to step Sb6. In step Sb6, it is determined whether or not the decompressed data expansion start address FEA that has been slid reaches a preset expansion address. Here, when the address FEA reaches the expansion address, it is considered that the decompression of the screen data is completed, and the decompression process is completed. On the other hand, if the decompressed data expansion start address FEA does not reach the expanded address, the process returns to step Sb2 and again to step Sb.
The compressed data is decoded into the screen data by repeating b2 to Sb5.

In the above decompression processing, the RAM 1c
Since the compressed file stored in is accessed, the number of accesses is reduced compared to the conventional file access mode, and the processing speed can be improved. That is, the conventional method is file access to the device via the OS, whereas the decompression processing is a complete internal calculation operation, which is extremely fast processing. Note that the speeding up of this processing depends on the compression rate, and the higher the compression rate, the more the effect can be expected.

[0026]

As described above, according to the present invention, screen data is written using the image storage area inside the main memory as a buffer area, and the screen data is encoded according to the redundant data component contained in the buffer area. The compressed data is stored in the file storage area of the main memory, and this compressed data is decoded into the screen data in the buffer area, so that the storage area of the main memory can be saved, and therefore many files can be expanded on the main memory. Even in such a case, high-speed display processing can be performed.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation of compression processing according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining address setting of a VRAM area in compression processing.

FIG. 3 is a diagram for explaining a slide operation in compression processing.

FIG. 4 is a flowchart showing an operation of decompression processing in the same embodiment.

FIG. 5 is a diagram for explaining address setting of a VRAM area in decompression processing.

FIG. 6 is a diagram for explaining a slide operation in decompression processing.

FIG. 7 is a block showing a configuration example of a handy terminal 1.

[Explanation of symbols]

1 ... Handy terminal, 1a ... CPU, 1b ... RO
M, 1c ... RAM, 1d ... Display circuit.

Claims (1)

[Claims] 1. A screen display method for expanding screen data stored in a file storage area of a main memory into an image storage area of the main memory and displaying the screen, wherein an address is provided so that the image storage area serves as a buffer area. The first step of setting and writing the screen data in the buffer area, detecting the data redundant component contained in the buffer area, and storing the compressed data encoded according to the detection result in the file storage area And a second step of performing the above-mentioned compressed data, wherein the compressed data is decoded into the screen data in the buffer area.