JPS61215584A - Display controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention includes a pixel expansion processing section that expands display information into pixel information, and a pixel memory that stores the pixel information output from the pixel expansion processing section, It relates to a display control device that outputs pixel information in the pixel memory to a display device or printer, and in particular, when pixel information in the pixel memory is deleted, inverted, or combined with new display information, pixel information in the pixel memory is This invention relates to control means suitable for setting.

[Background of the invention]

In general, a display control device is provided with a pixel memory for storing pixel information for the display device or printer in order to output one character information, one graphic information, image information, etc. to the display device or printer.

The second @ shows an example of the configuration of this type of device. 21st! 1, display information input from the host system 31 via the interface 32 is stored in the data memory 33 via the bus 38.

The pixel development processing unit 35 connects the data memory 33 to the bus 38.
The display information input via bus 3 is expanded into pixel information and
8 and stored in the pixel memory 34. Pixel memory 3
The pixel information of 4 is then displayed on the display device i (CRT) 36,
It is output to a printer (PR) 37 or the like.

In such a display control device, let us consider a case where pixel information in the pixel memory 34 is further read out from the data memory 33 by the pixel expansion processing unit 35 and deleted, inverted, or combined using the pixel expanded display information. .

Note that deletion refers to erasing the information in the pixel memory 34 using the pixel information output from the pixel expansion processing section 35. For example, as shown in FIG. 3, pixel memory information (1) and the pixel expansion processing section output AN of pixel information (2) corresponding to bits
1 inversion is to store the result (3) of the D operation at the same address in the pixel memory, and the information in the pixel memory 34 is changed from 0 to 1 according to the pixel information output from the pixel expansion processing unit 35. If it is 1, it is set to the opposite value to O. For example, as shown in Figure 3, exclusive OR (FOR) operation is performed on the pixel memory internal information (1) and the pixel expansion processing unit output pixel information (2) in a bit-wise manner. 0 compositing, which is storing the result (4) of As shown in FIG. 3, the result (5) of bitwise OR operation of the information in the pixel memory (1) and the pixel information (2) output from the pixel expansion processing section is stored at the same address in the pixel memory. In FIG. 3, in case 1, the pixel information (2) output from the pixel expansion processing section 35 contains II 071 and ``1''''.
are included, case 2 shows a case where all are 0'', and case 3 shows a case where all are #1 #l.

Conventionally, when performing such deletion, inversion, or composition, the contents of the 1-pixel memory 34 are read out regardless of the contents of the pixel information newly output from the pixel expansion processing section 35, and the pixel information output from the 1-pixel expansion processing section 35 is read out. Deletion 1 inversion or composition is performed by , and then stored at the same address in the pixel memory 34 . The necessary procedure for this is to first read one word from the pixel memory 34, then read out one word from the data memory 33.
The display information read from the pixel memory 34 is developed into pixel information, and then one word read from the pixel memory 34 is deleted.

The images are inverted or synthesized and then stored in the pixel memory 34.

However, as shown in Cases 2 and 3 in FIG. 3, when performing the deletion 1 inversion or compositing, the pixel information (2) output from the pixel expansion processing section is all 0. Alternatively, if the pixel information (2) output from the same pixel expansion processing section is all l (excluding inversion), the result can be predicted uniquely from the pixel information (2) output from the pixel expansion processing section without following the above procedure. I can do it. Generally, the pixel information output from the pixel expansion processing unit 35 is often all O or all 1, so in this case, if the above conventional procedure can be omitted,
It becomes possible to reduce the number of accesses to the pixel memory 34, and high-speed pixel development becomes possible.

In addition, related to this type of display control device is 1.
For example, Japanese Patent Laid-Open No. 58-208868 discloses that when the new pixel information to be deleted, inverted or combined is all 0 or all 1, no consideration is given to reducing the number of accesses to the pixel memory 34. Not yet.

[Purpose of the invention]

An object of the present invention is to provide a display control device that has a pixel memory and is controlled to delete, invert, or combine pixel information in the memory with new pixel information output from a pixel expansion processing section. When the new pixel information output from the pixel expansion processing section is all 0 or all 1, the purpose is to reduce the number of accesses to the pixel memory and enable faster pixel expansion processing.

[Summary of the invention]

The present invention provides a pixel information 0/1 detection section that detects whether the contents of new pixel information output from the 1-pixel expansion processing section are all O or all 1, thereby reducing the number of accesses to the pixel memory and processing the pixel expansion processing. It is characterized by the fact that the process can be carried out at high speed.

In other words, when deleting the contents of the pixel memory using new pixel information, if the new pixel information is all 0, the contents of the pixel memory are unconditionally set to 0 without reading out the contents of the pixel memory, and the new pixel information is deleted. If all pixel information is 1,
Prevent access to pixel memory. This is the case when the contents of the pixel memory are deleted when the new pixel information is 0, but when the contents of the pixel memory are deleted when the new pixel information is 1, the process can be reversed.

Next, when inverting the contents of the pixel memory using new pixel information, if the new pixel information is all 0, access to one pixel memory is not performed. This is a case where the contents of the pixel memory are inverted when the new pixel information is 1, but when the contents are inverted when the new pixel information is O, the opposite process may be performed.

Next, when combining the new pixel information with the information in the pixel memory, if the new pixel information is all 0, no access to the pixel memory is performed, and if the new pixel information is all 1, the pixel memory is not accessed. , the contents of the pixel memory are unconditionally set to all 1 without reading the contents of the pixel memory.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIG.
It is assumed that the pixel memory 34 itself in the figure is provided,
The configuration shown in FIG. 1 is the pixel development processing section 35 in FIG.
It is assumed that the Further, the information in the pixel memory 34 is deleted by new pixel information when the new pixel information is 0, and the information in the pixel memory 34 is inverted by 1 when the new pixel information is 1.

In FIG. 1, when a deletion request instruction is issued from a host system or the like, the contents of one pixel information l are recognized as all 0 by the pixel information 0/1 detection unit 2.

All 0 (ALLO) signal 20 causes pixel memory 34
The deletion request signal (DELREQ) 23 is suppressed and the signal (NR
EQ)22 is sent out.

When the pixel memory 34 receives the main signal (NREQ) 22, it does not read the internally stored information, but receives and stores the pixel information 1 on the data line 26 sent from the pixel expansion processing section 35. On the other hand, if the contents of the 5 pixel information 1 are recognized as all 1 by the pixel information 0/1 detection unit 2, all 1 (ALLI
) signal 21 suppresses the deletion request signal (DELREQ) 23 to the pixel memory 34, and no access to the 1-pixel memory 34 occurs.

If the content of pixel information 1 is a mixture of 0 and 1, as in case 1 in FIG. It will be done.

Similarly, when an inversion request instruction or a combination request instruction is issued, the pixel information 0/1 detection unit 2 detects the pixel information 1.
The contents of NREQ are checked, and if all O or all 1, each request signal to the pixel memory 34 is suppressed, and no access to the pixel memory 34 occurs or NREQ
An unconditional write by signal 22 occurs.

〔Effect of the invention〕

According to the present invention, in a display control device having a pixel memory, it is possible to omit access to the pixel memory for setting unnecessary pixel information, it is possible to perform high-speed pixel expansion, and the use of a bus is possible. It becomes possible to reduce the rate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an overall block diagram of a display control device having a pixel memory used in the present invention,
FIG. 3 is an explanatory diagram of a method of setting pixel information to a pixel memory used in the present invention. 1... Pixel information, 2... Pixel information 0/1 detection unit,
3.4...AND gate, 5,6...inverter, 7-OR gate, 8~1O-AND gate, 2
0... Pixel information all 0 detection signal, 21... Pixel information all 1 detection signal, 22... Unconditional write request signal, 23... Delete request write signal, 24... Inversion request write signal, 25...Synthesis request write signal,
33...Data memory 1.34...Pixel memory,
35... Pixel expansion processing section. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) In a display control device comprising a pixel expansion processing section that expands display information into pixel information, and a pixel memory that stores pixel information output from the pixel expansion processing section, the pixel information output from the pixel expansion processing section detecting means for detecting that the pixel information stored in the pixel memory is pixel information whose storage unit length is all 0 or all 1; 1. A display control device comprising: control means for controlling storage of pixel information in the pixel memory according to a detection result of the detection means when deleting or inverting pixel information or composing both pixel information.