JP2910154B2 - Character generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition character generation circuit that converts an outline font used for printing characters and symbols into a raster font and outputs the raster font. The present invention relates to a character generation device capable of performing a high-speed operation.

2. Description of the Related Art When printing a document created by a document creation device such as a Japanese word processor, a font represented by a dot matrix has been conventionally used. Such a conventional font reads out this as it is and
Characters and symbols (hereinafter simply referred to as characters) can be printed by a method such as recording a raster by a dot printer or raster scanning by a laser printer. However, fonts using a dot matrix have the following problems in printing.

(I) Since a character is composed of dots, its outline is not smooth, and high-quality characters cannot be printed unless dots are arranged at high density.

(Ii) When printing characters of various sizes, a font must be prepared for each character. This requires a large-capacity memory for storing character fonts.

In order to solve such a drawback, an outline font in which an outline of a character is represented by vector data has been used. In the case of an outline font, the outline of the character is smoothed, and since the data does not depend on the font size, there is no need to prepare a font for each size.

However, when an outline font is used, the outline of each character is sequentially expanded in the memory based on the vector data, and the insides of those lines are filled in, and the outline font is used. A process of generating a raster image is required. Such a process requires more time than a conventional character generation circuit that simply reads out a character pattern stored in a memory. Therefore, various types of dedicated circuits for generating raster images at high speed have been proposed, but there is a limit to the reduction of processing time, and when generating high-quality characters, the printing speed must be sacrificed to some extent. I had to do it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a character generator capable of outputting raster data at high speed irrespective of a circuit for developing a raster image.

[Means for Solving the Problems] According to the first aspect of the present invention, rasterizing means for rasterizing vector data representing fonts of characters and symbols into raster data, and a font size of raster data rasterized by the rasterizing means is predetermined. Size determining means for determining whether or not the value is within a value; a font cache memory for storing raster data developed when the font size is determined to be within a predetermined value; characters and symbols; When the font data is requested and the raster data is stored in the font cache memory, the character generator is provided with output means for reading and outputting the raster data from the font cache memory.

According to the first aspect of the invention, when characters and symbols are generated using an outline font, the size determination unit determines whether or not the font size of the expanded raster data is within a predetermined value. When it is determined that the font size is within the predetermined value, the raster data expanded is stored in the font cache memory, and the next time a font request for characters or symbols is made, the raster data is stored in the font cache memory. In this case, the font cache memory is efficiently used.

According to the second aspect of the present invention, a size determining means for determining a font size of a character or a symbol to be generated, a cache memory for storing a plurality of raster data of the character or the symbol having a size within a predetermined value, When a font is requested, the character or symbol determined by the size determination unit to have a size equal to or larger than the predetermined value and the character or symbol determined to have a size within the predetermined value and not stored in the cache memory are converted to vector data. The character generator is provided with raster data output means for developing raster data and outputting the raster data, and outputting raster data stored in the cache memory otherwise.

According to the second aspect of the present invention, when characters are generated using an outline font, vector data is unconditionally developed into raster data for characters having a certain size or more, and data corresponding to a cache memory is stored otherwise. Is developed into raster data only when the character does not exist, the hit rate of the cache memory is increased for characters having a high probability of occurrence, and the object described above is achieved.

"Example" Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 shows the configuration of a character generator according to an embodiment of the present invention. The system data bus 11 of the high-quality character generation circuit transfers a character code representing a code of a character to be output, raster data expanded by this circuit, and the like. Among them, the character code representing the character whose printing is instructed is stored in the character code register 12 from the system data bus 11.

The character code register 12 selects a character code from the relationship with the character size. If the character code generates a character smaller than a predetermined size, the character code
Is compared with all the character codes stored in. When the comparison circuit 15 detects a match with any of the character codes, a cache hit signal 16A is output to the system data bus 11. If a match cannot be detected because the corresponding character code does not exist, a cache hit / miss signal 16B is output to the system data bus 11.

When the cache hit miss signal 16B is output, the corresponding character code is stored in the cache tag memory 14 via the buffer amplifier 13. The character code at this time is stored in the area indicated by the tag memory address 18 randomly output from the random address generation circuit 17. Then, the character generation device generates an outline font corresponding to the character code and performs control for storing the outline font in the cache memory 21.

That is, the corresponding character code stored in the character code register 12 is supplied to the outline developing circuit 22 as a dedicated hardware circuit at this time. The outline expanding circuit 22 is connected to a font data storage unit 23 storing font data as vector data, and expands vector data for expressing a designated font. The address information 24 indicating the expanded outline is one input of the multiplexer 25. The other end of the multiplexer 25 is supplied with address information 27 from a system address bus 26.

The output of the multiplexer 25 is connected to a font development memory 28.
Supplied to At this time, in the case of the address information 24 supplied from the outline expanding circuit 22, the corresponding font is expanded while designating the address of the font expanding memory 28. In this way, the font expansion memory
28 contains outlines of multiple fonts. The contents of the font development memory 28 are read out by the address information 27 supplied from the system address bus 26, and are filled out as outline font data 29.
Supplied to 31. The raster data in which the inside of the outline is filled by the filling circuit 31 is supplied to a printer (not shown) through the system data bus 11.

The outline font data 29 output from the font development memory 28 is stored in the cache memory described above.
The outline of the character font is drawn in the corresponding area obtained by adding the address 33 supplied to the offset circuit 32 and offset by the offset circuit 32. At this time, an offset value 34 indicating the storage location of the cache memory 21 is stored in the cache tag memory 14 together with the above-described character code. This offset value 34 is used as an offset value generation circuit.
Output from 35.

On the other hand, when the cache hit signal 16A is output from the comparison circuit 15, since the outline font of the corresponding character code is stored in the cache memory 21,
It is enough to read this. Therefore, in this case, the offset value 34 stored together with the corresponding character code in the cache tag memory 14 is read, and
Supplied to 21. The outline font data 29 read out from the cache memory 21 based on the outline font data 29 is supplied to a filling circuit 31, where the inside of the outline is filled, and supplied to the printer via the system data bus 11. .

Different from the above, a case where the character code register 12 determines that the character code is a character code of a character having a predetermined size or more will be described. In this case, the character code is immediately sent to the outline developing circuit 22, and the outline is developed in the font developing memory 28 based on the address information 24 generated based on the character code. In this case the address information
The outline font data 29 read out by the font development memory 28 and output from the font development memory 28 is
Only 31 will be supplied. That is, in this case, the data is not stored in the cache memory 21 for reuse.

FIG. 2 specifically shows a main part of the character generator shown in FIG. In the cache memory 14, a character code and an offset value are stored as a pair as shown in FIG. Character code registered in character code register 12 and cache tag memory
Each character code in 14 is compared in parallel by a comparison circuit 15, and the OR of these comparison results is taken and a cache hit signal 16A or a cache hit miss signal 16B is output. ing. The offset value 34 stored in the cache tag memory 14 corresponding to each character code is provided by an offset value generation circuit 35.

FIG. 3 shows the relationship between the offset value output from the offset value generation circuit and the storage area of the outline font on the cache memory. In this character generation device, only characters within a certain size among characters to be generated are stored in the cache memory 21. This is a limitation for effectively using a finite storage area. In the present embodiment, the storage area is divided into a rectangular shape with an a-bit width both vertically and horizontally, and outline font data of a character size within a × a size is stored in each of the storage areas.

In this case, the offset value generating circuit 35 outputs an offset value representing the coordinates of the lower left corner in the figure of each rectangular storage area. That is, first, the coordinate value of the origin (0,0) of the cache memory 21 is output as the offset value. Second, the coordinate value of the point (a, 0) shifted by the offset amount a in the X-axis direction in the figure is output as the offset value. Similarly, the offset value for the third point is (2a, 0), and the offset value for the fourth point is (3a, 0).

When all the areas where the Y coordinate of the cache memory 21 is “0” are allocated in this manner, the offset value generation circuit
Numeral 35 returns the X-axis coordinate value to "0", adds the offset amount for the Y coordinate by "a", and sequentially generates an offset value in the same manner. In this case, the offset value (0, a) is output first, and then the offset value (a, a) is output. In the same manner, offset values are sequentially generated so as to partition the entire area of the cache memory 21 in the same manner.

Offset value output from offset value generation circuit 35
34 is supplied to the offset circuit 32 described above. The offset circuit 32 is constituted by an adder, and an X address X ₁ to be written to the cache memory 21 based on the X coordinate address X ₁ and the Y coordinate address Y ₁ for each outline output from the multiplexer 25 in FIG. generating a ₂ and Y coordinate address Y _2. Here, assuming that the offset value is (X ₃ , Y ₃ ), the X address X ₂ and the Y coordinate address Y
₂ has the relationship of the following equation (1).

X ₂ = X ₁ + X ₃ , Y ₂ = Y ₁ + Y ₃ (1) As a result, the outline of each character is developed in the divided storage area as shown in FIG.

By the way, the cache hit / miss signal 16B output from the comparison circuit 15 in this character generation device is supplied to the random address generation circuit 17. The random address generation circuit 17 randomly generates an address in the cache tag memory 14 to receive the cache hit / miss signal 16B. A new character code and offset value pair is stored for the generated address. That is, the outline font data stored in the cache memory 21 is sequentially replaced with new one.

Of course, the random address generation circuit 17 generates an address so as to fill the empty area when there is an empty area in the cache tag memory 14, and randomly generates an address after the empty area disappears. You may. Further, it is also possible to use an address generating circuit for designating an address to make one round, instead of the random address generating circuit 17. In the latter case, the oldest content at that time will be replaced with new content.

[Effect of the Invention] As described above, according to the invention of claim 1,
Size determination means determines whether the font size of raster data once expanded is within a predetermined value, and stores the raster data expanded in the font cache memory when it is determined that the font size is within the predetermined value. Therefore, when a large number of characters and symbols are requested for the next font, the raster data can be read from the font cache memory and output. Can be used efficiently.

According to the second aspect of the present invention, the size of the raster data stored in the font cache memory is limited, so that the memory can be used efficiently and high-quality characters can be stored with a relatively inexpensive circuit configuration. There is an advantage that high-speed processing can be performed.

[Brief description of the drawings]

1 is a block diagram showing a circuit configuration of a character generator, and FIG. 2 is a block diagram specifically showing a main part of the device. FIG. 3 is an explanatory diagram showing the relationship between the storage area for each character in the cache memory and the offset value. 12 ... Character code register, 14 ... Cache tag memory, 15 ... Comparison circuit, 21 ... Cache memory, 23 ...
Font data storage unit, 28 ... Font expansion memory,
32 ... Offset circuit, 35 ... Offset value generation circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G09G 5/22-5/32 G06F 17/20-17/21 G06F 3/14-3/153

Claims (2)

(57) [Claims] A developing means for developing vector data representing a font of characters or symbols into raster data; and a size discriminating means for judging whether or not the font size of the raster data developed by the developing means is within a predetermined value. Means; a font cache memory for storing the raster data expanded when the font size is determined to be within a predetermined value by the size determining means; and a raster data when a font for characters or symbols is requested. Output means for reading and outputting raster data from the font cache memory when the font data is stored in the font cache memory. 2. A size discriminating means for discriminating a font size of a character or a symbol to be generated, a cache memory for storing a plurality of raster data for a character or a symbol having a size within a predetermined value, and a request for a font of a character or a symbol. When there is a character or symbol determined by the size determination means to be a size equal to or larger than a predetermined value, and for a character or symbol not stored in the cache memory, these vector data are rasterized. And a raster data output means for outputting raster data stored in the cache memory after outputting the raster data.