JP2829051B2 - Character display method - Google Patents

Description

Detailed Description of the Invention [Table of Contents] Overview Industrial application field Conventional technology Problems to be solved by the invention Means to solve the problem Actions Embodiment I. Correspondence between the embodiment and FIG. 1 II Configuration of the Embodiment III. Operation of the Embodiment IV. Summary of the Embodiment V. Modifications of the Invention Effects of the Invention [Summary] Regarding the character display method in the graphic display device, the purpose is to make effective use of software resources. A graphic display means having pixel data storage means for storing pixel data, display means for performing display based on the pixel data stored in the pixel data storage means, and pattern data representing characters and symbols. A pattern data storage unit, a character buffer for storing pattern data at a specified address, and a character buffer address corresponding to the input display position are designated and input. A first processing unit for writing pattern data retrieved from the pattern data storage unit based on the character code, and an address designated at the time of the writing process by the first processing unit are sequentially stored, and at least one address is stored. Address display means for outputting a read request signal when the image data is read, and a graphic display process for generating pixel data representing a graphic and storing the pixel data in the pixel data storage means, and performing address storage according to the read request signal. Second processing means for performing a process of transferring the pattern data stored in the character buffer to a corresponding storage location of the pixel data storage means based on the address stored in the means.

[Industrial applications]

The present invention relates to a character display method in a graphic display device.

As a display device of a workstation used in a computer-aided design (CAD) system or the like, a graphic display device emphasizing a graphic display function is used.

Since graphic display devices mainly perform graphic display, some graphic display devices do not have a character display mechanism as used in character display devices.

On the other hand, in such a graphic display device as well, there is a demand for displaying kanji in the same manner as the character display device.

[Conventional technology]

FIG. 5 shows a configuration of a workstation provided with a conventional character display device. FIG. 6 shows a configuration of a workstation provided with a conventional graphic display device.

When a character is displayed on a workstation equipped with a conventional character display device, a character to be displayed is stored in a character buffer 512 corresponding to a position where the character is displayed by a microprocessor (MPU) 511. The character code shown is stored. The display control unit 513 reads a character code from the character buffer 512 and supplies it to a character generator (CG) 514. According to the character code, pattern data representing the corresponding character is output from the CG 514, converted into a video signal, and displayed on the cathode ray tube (CRT) 515.

As described above, it is assumed that the workstation including the character display device includes a character display mechanism including the character buffer 512 and the CG 541.

Further, character display devices are more widespread than graphic display devices, and the amount of software applied to workstations and personal computers using the character display devices is enormous.

On the other hand, in a workstation provided with a conventional graphic display device, the MPU 621 generates pixel data representing a graphic based on the input coordinate data and the drawing instruction, stores the pixel data in the graphics memory 622, and displays the display control unit. The 623 controls the CRT 624 so as to perform display based on the pixel data stored in the graphics memory 622.

[Problems to be solved by the invention]

By the way, since the conventional graphic display device described above does not include a character buffer and a CG, it is not possible to display characters using software applied to a workstation equipped with the character display device as it is, and it is enormous. There was a problem that software resources could not be utilized.

When attempting to display characters using the graphic display device as described above, it is necessary to represent each character as a graphic.

Also, just by adding a character buffer and CG,
Since it is necessary to control the character buffer and CG by the MPU621 of the workstation using the graphic display device,
Significant changes have to be made to character display programs.

The present invention has been made in view of such a point, and an object of the present invention is to provide a character display method that effectively utilizes software resources by adding hardware for character display processing. And

[Means for solving the problem]

FIG. 1 is a block diagram showing the principle of the character display system according to the present invention.

In the figure, a graphic display unit 110 includes a pixel data storage unit 111 for storing pixel data, and a pixel data storage unit 111.
And a display unit 112 for performing display based on the pixel data stored in the storage device.

The pattern data storage unit 121 stores pattern data representing characters and symbols.

The character buffer 122 stores the pattern data at the specified address.

The first processing means 124 searches the pattern data storage means 121 based on the input character code, specifies the address of the character buffer 122 corresponding to the input display position, and writes the searched pattern data. Perform processing.

The address storage unit 123 sequentially stores the addresses specified during the writing process by the first processing unit 124, and outputs a read request signal when at least one address is stored.

The second processing unit 131 performs a graphic display process of generating pixel data of a pixel representing a graphic and storing the pixel data in the pixel data storage unit 111, and is stored in the address storage unit 123 in response to the read request signal. Based on the address, a process of transferring the pattern data stored in the character buffer 122 to a corresponding storage location of the pixel data storage unit 111 is performed.

(Operation)

Based on the input character code, the first processing unit 124
Thus, the corresponding pattern data is retrieved from the pattern data storage means 121, and this pattern data is stored in the address of the character buffer 122 corresponding to the input display position.

At this time, the address of the character buffer 122 is stored in the address storage means 123, and when at least one address is stored, the address storage means 123 outputs a read request signal. For example, address storage means
What is necessary is just to output the read request signal when the address is stored to half of the capacity of 123.

In response to the read request signal, the second processing means 131 causes the character buffer 122 stored in the address storage means 123 to be stored.
Is transferred to the corresponding storage location of the pixel data storage unit 111.

In the present invention, the first processing means 124, the pattern data storage means 121, the character buffer 122, the address storage means 123
Operate as a character display mechanism that performs processing for character display. Also, in response to the read request signal from the address storage means 123, the second processing means 131 causes the character buffer 1
The pattern data stored in 22 is stored in the pixel data storage
By transferring the data to 1, the display by the display means 112 is performed based on the pattern data representing the characters and symbols. This makes it possible to utilize the software resources created on the assumption that the character display mechanism is provided, without largely changing the software of the second processing unit 131.

〔Example〕

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

FIG. 2 shows a configuration of a workstation to which a character display method according to an embodiment of the present invention is applied.

I. Correspondence Between Embodiment and FIG. 1 Here, the correspondence between the embodiment of the present invention and FIG. 1 will be described.

 The graphic display means 110 corresponds to the graphic display device 210.

The pixel data storage unit 111 corresponds to the graphics memory 212.

 The display means 112 corresponds to a cathode ray tube (CRT) 211.

The pattern data storage unit 121 corresponds to the pattern data area 232 of the memory 223.

The character buffer storage unit 122 corresponds to the character buffer area 233 of the memory 223.

The address storage means 123 is a first-in first-out memory (FIF
O) 222.

The first processing means 124 includes a microprocessor (MPU) 221
Is equivalent to

 The second processing unit 131 corresponds to the MPU 201.

An embodiment of the present invention will be described below assuming that there is the above correspondence.

II. Configuration of the embodiment In FIG. 2, 201 is a 32-bit microprocessor (MPU), 210 is a graphic display device, 211 is a cathode ray tube (CR).
T), 212 is a graphics memory, 213 is a display control unit, 214
Is a signal conversion unit. The workstation is configured to include these units, and includes the MPU 201 and the graphic display device 21.
0 is mutually connected via the bus 202.

Each storage location of the graphics memory 212 of the graphic display device 210 stores pixel data corresponding to each pixel of the display screen of the CRT 211.

The pixel data stored in the graphics memory 212 is converted into a video signal by the signal
211, and the display control unit 213
The CRT 211 and the signal conversion unit 214 are controlled so that an image is displayed by the CRT 211 based on the pixel data stored in the graphics memory 212.

221 is a 16-bit MPU, 222 is a first-in first-out memory (FIFO) having a capacity of 512 words, 223 is a memory having a capacity of 1 Mbyte, and 224 is a stator register. The character display adapter 220 includes these components, and the MPU 221 and the memory 223 are connected to the address bus 2.
They are connected via a bus 224 including a data bus 24a and a data bus 224b. The FIFO 222 is connected to the address bus 2 of the MPU 221.
24a, the address of the memory 223 is written to the FIFO 222 when the MPU 221 writes data to the memory 223.

The character display adapter 220 is configured to be inserted into an expansion slot (not shown) of the workstation. Through this expansion slot, the FIFO 222, the memory 223, and the status register 224 are connected to the bus 202 of the MPU 201. It is to be connected.

The memory 223 includes a program area 231, a pattern data area 232, and a character buffer area 233.

The program area 231 stores a program related to character display processing in an operation system (OS) from an auxiliary storage device (not shown) such as a disk device when the workstation is started. .

The MPU 221 operates in accordance with the program stored in the program area 231 in response to a character display processing request from an application program executed by the MPU 201. Here, the program related to the character display processing stored in the program area 231 is the same program as the program using the conventional character display device.

In the pattern data area 232, pattern data representing the corresponding characters and symbols is stored in advance corresponding to the character codes indicating the characters and symbols. Alternatively, such pattern data may be stored in the auxiliary storage device in advance, and the pattern data may be stored in the pattern data area 232 when the workstation is started.

The character buffer area 233 is formed from a plurality of small areas corresponding to each character display position on the display screen of the CRT 211. For example, when the CRT 211 can display characters of 80 columns × 24 lines, the character buffer area 233 is formed from 80 × 24 small areas.

III. Operation of Embodiment When displaying characters in an application program executed by the MPU 201, the application program specifies a character code to be displayed and a display position for a program relating to character display processing. ,
Request character display processing.

In response to this character display processing request, the character display adapter 22
0 MPU 221 stores memory 2 based on the specified character code.
The 23 pattern data areas 233 are searched, and the corresponding pattern data is stored in the small area corresponding to the designated display position in the character buffer area 233. At this time, the start address of the small area where the pattern data is written is written to the FIFO 222.

In this way, in response to a character display processing request from the application program, the pattern data corresponding to the designated character code is stored in the character buffer area 233, and the start address of the storage location of the pattern data in the character buffer area 233 is stored in the FIFO 222. , And a character display process is performed.

The FIFO 222 is configured to output a logic “0” as a half-full signal S _HF from the output terminal O _HF when the above-mentioned address is written to half of the capacity (256 words). full signal S _HF is supplied to MPU201 as an interrupt request signal, is adapted to set the change notification flag in the status register 224.

The MPU 201 performs an interrupt signal described below in response to the above-described interrupt request signal.

 FIG. 3 is a flowchart showing an interrupt processing operation.

First, the MPU 201 refers to the status register 224 of the character display adapter 220, and determines whether or not the display screen of the CRT 211 needs to be changed based on whether or not the change notification flag has been set (step 301).

Here, the change of the display screen means the display of a new character, the change or deletion of the displayed character.

If the change notification flag is set, the affirmative determination is made in step 301 described above, and the MPU 201
The address of the character buffer area 233 is read from 22 (step 302), and the pattern data is read from the corresponding small area of the character buffer area 233 (step 303).

Next, the MPU 201 calculates the start address of the area of the graphics memory 212 corresponding to the corresponding display position on the display screen of the CRT 211 based on the address of the character buffer area 233 read in step S302, and The pattern data read in S303 is stored (step 304).

In this way, the pattern data read from the character buffer area 233 is stored in the corresponding area of the graphics memory 212, and thereby the display screen of the CRT 211 is changed.

In the MPU 201, the half full signal S _HF of the FIFO 222 is logic “1”.
As a result, the change notification flag of the status register 224 is reset, and the processing of steps 301 to 304 described above is repeated until a negative determination is made in step 301 described above.

Also, as an interrupt request signal to the MPU 201, the FIFO 222
In place of the half-full signal S _HF, it may be used empty signal S _E becomes the logic "1" when FIFO222 is empty. In this case, the status register 22
4, when the empty signal S _E is logic "0", it is sufficient to set the change notification flag described above.

If the writing speed of the MPU 221 to the FIFO 222 is faster than the reading speed of the address from the FIFO 222 by the MPU 201, the address is written to the full capacity of the FIFO 222. At this time, FIFO222 is configured to output a logic "0" as the full signal S _F from the output terminal O _F, as the full signal S _F is hold signal S _HOLD, MPU
221. The operation of the MPU 221 is temporarily stopped while the hold signal S _HOLD is logic “0”.

As described above, in the state where the address is written to the full capacity of the FIFO 222, the character display processing operation by the MPU 221 is temporarily stopped until the address previously written by the MPU 201 is read.

On the other hand, and when performing screen refreshing, such as when performing cancellation of the input data, the MPU 201 outputs a reset signal S _R, to the control terminal R of the FIFO 222. F
The IFO 222 outputs the reset signal S _R supplied to the control terminal _R.
Depending on to reset the writing position address, and outputs a logical "1" as a half-full signal S _HF, and full signal S _F described above. In addition, the change notification flag of the status register 224 is reset according to the change of the half-full signal _SHF .

Further, there is a case where it is desired not to temporarily stop the MPU 221 in a state where the address is written to the full capacity of the FIFO 222 as described above.

In this case, the MPU 201 performs the interrupt processing shown in FIG. 4 according to the interrupt request signal supplied from the FIFO 222. In this case, the full signal S _F of FIFO222 is set full notification flag in the status register 224 when a logic "0", so as to reset when a logic "1".

First, the MPU 201 refers to the status register 224,
It is determined whether or not the full notification flag is set (step 401), and in the case of a negative determination, it is determined whether or not the display screen of the CRT 211 needs to be changed (step 402). In the case of an affirmative determination in step 402, the MPU 201
The address is read from IFO 222 (step 40
3) The pattern data is read from the character buffer area 233 based on this address (step 404) and stored in the corresponding area of the graphics memory 212 (step 4).
05).

In the same manner as in the case of pause MPU221 by full signal S _F as described above, until the negative determination in step 402, and repeats the steps 401 to 405.

On the other hand, in the case of an affirmative determination in step 401, the MPU 20
1 resets the writing position FIFO222 outputs a reset signal S _R as described above (step 406), performs a refresh of the entire screen (step 407), after execution of step 407, the process returns to step 401.

IV.Summary of Embodiment As described above, a character display adapter 220 having an MPU 221, a FIFO 222, a memory 223, and a status register 224 is added to a workstation having the graphic display device 210, and a pattern data area of the memory 223 is added. The pattern data is stored in 232 and the program related to the character display processing is stored in the program area 231 and activated.

As a result, in response to a character display processing request from the application program, processing for character display is performed by the MPU 221, the FIFO 222, and the memory 223, and a pattern corresponding to the character code specified in the character buffer area 233 of the memory 223. The data is stored. The character display adapter 22
Interrupt request signal from 0 (half-full signal of FIFO222
By performing the above-described interrupt processing in accordance with S _HF ), this pattern data is transferred to the graphics memory 212, and characters can be displayed on the CRT 211 of the graphic display device 210 based on the pattern data. .

As described above, the character display can be performed by adding the above-described interrupt processing program as the program of the MPU 201 without changing the application program.

The character display adapter 220 described above is a commercially available MPU, F
It can be configured using elements such as an IFO and a memory.

〔The invention's effect〕

As described above, according to the present invention, the first processing means, the pattern data storage means, the character buffer, and the address storage means perform the processing for character display, and the second processing means stores the pattern data stored in the character buffer. Is transferred to the pixel data storage means, the character display can be performed by the display means, and software resources based on the existence of a character display mechanism can be used, which is extremely useful in practice. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the character display system according to the present invention.
FIG. 1 is a block diagram of a workstation to which a character display system according to an embodiment of the present invention is applied, FIGS. 3 and 4 are flowcharts showing an interrupt processing operation of the embodiment, and FIG. FIG. 6 is a configuration diagram of a workstation provided with a conventional graphic display device. In the figure, 110 is a graphic display means, 111 is a pixel data storage means, 112 is a display means, 121 is a pattern data storage means, 122 is a character buffer, 123 is an address storage means, 124 is a first processing means, and 131 is a second processing means. Processing means, 201,221,511,621 are microprocessors (MPU), 202,224 are buses, 210 is graphic display device, 211,515,624 is cathode ray tube (CRT), 212,622 is graphics memory, 212,513,623 is display control unit, 214 is signal conversion unit, 220 is character display An adapter, 222 is a first-in first-out memory (FIFO), 223 is a memory, 231 is a program area, 232 is a pattern data area, 233 is a character buffer area, 512 is a character buffer, and 514 is a character generator (CG).

Claims (1)

(57) [Claims] 1. A pixel data storage means (111) for storing pixel data, and a display means (112) for performing display based on the pixel data stored in the pixel data storage means (111).
A pattern data storage means (121) for storing pattern data representing characters and symbols; a character buffer (122) for storing the pattern data at a specified address; Searching the pattern data storage means (121) based on the input character code, and specifying the address of the character buffer (122) corresponding to the input display position, and writing the searched pattern data A first processing means (124) for performing a write operation, and sequentially storing addresses designated at the time of writing processing by the first processing means (124), and outputting a read request signal when at least one address is stored. An address storage means (123) for performing a graphic display process of generating pixel data of a pixel representing a graphic and storing the generated pixel data in the pixel data storage means (111); In response to the output request signal, the pattern data stored in the character buffer (122) is stored in a corresponding storage location of the pixel data storage means (111) based on the address stored in the address storage means (123). And a second processing means (131) for performing a transfer process.