JPH0127469B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides characters using a raster scanning type CRT.
In a graphics device where one dot of a display pattern is made up of one or more bits of the contents of a video memory that stores pattern information of a figure (pattern) display device, the address of the position to be drawn is calculated and determined. Concerning drawing address calculation method.

Raster scanning type as a computer terminal device
A graphic display/drawing device using CRT is
As the required large-capacity video information storage devices become highly integrated circuits, their prices are decreasing and they are rapidly becoming popular. There are roughly two types of techniques for inputting video information into a video information storage device built into a graphic display/drawing device.

The first method is to create video information using a drawing device that has the function of drawing straight lines, circular graphs, etc. based on a database. It stores information by digitizing analog signals obtained by

Devices that draw characters include those that use a method generally called the stroke method, which forms characters by connecting two points with straight lines, and devices that draw characters in units of dots while referring to the dot composition information of the character. There are two types of methods that have been used in the past: one that uses a drawing method.

The stroke method has traditionally been a direct scanning type.
This method was already used in graphics devices using CRTs, and is a raster scanning type CRT.
It may also be used in graphic devices using In this case, characters are constructed by repeatedly drawing straight lines using solid lines connecting two points. FIG. 1 shows an example of character drawing using the stroke method, and in order to draw the character "A" shown in the figure, straight line drawing using solid lines must be executed a total of six times. In this stroke method, drawing is performed line by line, so when attempting to add fine accents to the dot structure forming a character, the number of line drawings increases, making the process difficult. Furthermore, even when the outer shape of a character is large, such as a kanji character, it is difficult to change the line width, making it impossible to obtain good character display quality. Furthermore, it has the disadvantage that the design is complicated because characters must be expressed in a special format called a coordinate change table.

In order to eliminate these drawbacks of the stroke method, devices have already been considered that form characters by drawing dots instead of lines. The difference from the stroke method is that each time one block is drawn, the character dot configuration pattern is referred to and drawing is performed according to its contents. This device does not require solid line interpolation between two points as in the stroke method.

Figure 2 shows the letter “A” made up of 8 x 8 dots.
FIG. 4 is a diagram showing the drawing results obtained by drawing according to a conventional example using the dot-by-dot drawing method and the locus of the drawing order with arrows. To draw one block from the drawing start point of (I, J) = (1, 1) to point (1, 8), dots are drawn while referring to the data of the character dot configuration pattern (in this case "00000000") one by one. Obtained by drawing 8 times per unit. After drawing this one block, the character dot configuration pattern to be drawn next is reset in the register (“10000010”), and the character dot configuration pattern to be drawn next is reset to the register (“10000010”), and the character dot configuration pattern to be drawn next is set in the register (“10000010”), and
Draws the next block up to. After repeating this process and drawing at point (8, 8), all eight blocks have been drawn and the character pattern "A" is displayed.

FIG. 5 is a diagram showing the relationship between the word address of the video memory to be drawn and the drawing data in the drawing embodiment. In a normal character display device, video memory data is changed in word address units, but in a drawing device that can execute dot-based drawing, the drawing start point can be set at any arbitrary point within the word address, as shown in Figure 5. The bit position is fine. Therefore, it is also possible to draw across multiple addresses. FIG. 6 is a diagram showing the order of dot unit drawing when performing the drawing shown in FIG. It expresses that drawing starts from the point directly above the starting point of and ends at. That is, the drawing direction was always the same (from left to right).

For this reason, as shown in FIG. 3, which is a flowchart of the drawing coordinate calculation, that is, the drawing address calculation, in the conventional example, the horizontal (X) coordinate data x of the drawing start point is stored in registers X, X', and the vertical (Y) coordinate Data y is stored in registers Y and Y' respectively, and the X address of each drawing position for one block is calculated while increasing the contents of register X by one. When drawing for a block is completed, registers Y and Y' are incremented by one, and the contents of register X' are transferred to register X.
The drawing address of the next block is calculated.

Thus, the hardware of the X and Y coordinate address calculation unit according to the prior art is as shown in FIG.
Requires 3 and 4. The CPU 5 transfers address data x and y of the drawing start point to registers 1 to 4, respectively. The drawing address for one block is determined by the incrementer 6, which increments the contents of the X register 1 by one, and when the drawing address for one block is determined, the contents of the Y register 3 are incremented by the incrementer 7. As well as being increased by one,
The contents of X' register 2 are transferred to X register 1.

As described above, the X and Y addresses of each drawing position in the area to be drawn are calculated. and,
Based on the calculated X and Y addresses, character data is drawn according to the procedure shown in FIG. In FIG. 8, a represents the relationship between the contents of a pattern register that stores information for one block of character data to be drawn and the drawing address of the video memory where drawing is executed, applied to the example shown in FIG. Figure b shows the contents of each register that change according to the drawing procedure. First, the CPU 5 (FIG. 10) transfers the coordinates x and y of the drawing start point to the X, X', Y, and Y' registers 1 to 4, respectively. For convenience of explanation, the drawing start point is shown as a word address and a dot address in FIG. X′) register 1
The rest of the contents of (2) and Y (Y') register 3
The contents of (4) are shown below. Next, the CPU 5 transfers information for one block of character data to a pattern register (not shown in FIG. 10). Fifth
In the example shown, the contents of the pattern register are shown in Figure 8a.
As shown in the figure, it is “10111110”. Here, the least significant bit of the contents of the pattern register does not match the information of the dot address. Therefore, Fig. 8b
The contents of the pattern register are rotated within the register according to the information of the dot address, as shown as "first dot", to align the least significant bit of the pattern data to be drawn. Then, the data in the pattern register pointed to by the dot address is selected and written as dot data to the video memory addressed by the word address and dot address. After drawing the first dot, the dot address is incremented by an incrementer 6, and the address location in the video memory is changed. As a result, the designated position of the pattern register is changed and new drawing data is selected. When the drawing of 8 dots (1 block) is completed, the Y coordinate value at the start of drawing of the first block stored in the Y register 3 is incremented, and the data indicating the first Y coordinate value of the next second block becomes Y. 'Transferred to register 4. The X coordinate value at the start of drawing of the first block, which was stored in the X' register 2, is transferred to the register X as is. After that, the new character composition dot pattern corresponding to the second block is added to the pattern.
The data is transferred to a register and aligned in the same manner as described above. Thereafter, the above operations are repeated.

As mentioned above, the conventional dot unit drawing device executes drawing address calculation, but the drawing address includes a discontinuous part where the address changes when the block is switched.・Two register systems (i.e.
and X′, Y and Y′), which increases the hardware size. Moreover, processing is required for each register access, and the processing speed is relatively slow.

An object of the present invention is to provide a drawing address calculation method that reduces hardware size and increases processing speed.

The method according to the present invention includes a first register that stores data indicating the X address of the drawing position, a second register that stores data indicating the Y address of the drawing position, and a second register that increments the contents of the first register by one. a second means for decreasing the contents of the first register by one; a third means for increasing or decreasing the contents of the second register by one; and a means for transferring data indicating the Y address, respectively,
The present invention is characterized in that switching between increasing the X address by the first means and decreasing the X address by the second means is performed every time the Y address changes by the third means.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4a is a flowchart of drawing address calculation according to an embodiment of the present invention. First, horizontal address data x and vertical address data y of the drawing start point are transferred to X and Y addresses, respectively. By character data reference, character data information for one block is transferred to the pattern register, and in this embodiment, first, the contents of the X address are incremented one by one to calculate the drawing position address, and drawing is performed at each drawing position. When drawing for one block is completed, Y
The contents of the register are incremented by 1, and the 1-dot data of the character data information of the next block executes drawing using the contents at that time and the contents of the Y register as the drawing position address without changing the contents of the X register. . Then, change the contents of the X address to 1
The drawing position address is calculated by decrementing the drawing position address. Thereafter, each time the contents of the Y register change, the direction of change of the contents of the X address is switched to calculate each drawing address. Therefore, the X′ register and Y′ register that were necessary in the conventional example are no longer necessary.
In addition, address transfer every time blocks are switched becomes unnecessary.

Thus, the hardware according to this method is
As shown in Figure b,
Two registers, register 8 and Y register 9, are sufficient. However, an incrementer 11 that performs a +1 operation and a decrementer 12 that performs a -1 operation are provided for the contents of the X register 8, and block switching,
That is, each time the contents of the Y register 9 change by one by the incrementer 13, the above two operations are switched. Drawing start point address data to the X and Y registers 8 and 9 is set by the CPU 10.
To explain in more detail, the address data x, y indicating the coordinates of the drawing start position of the first block is
10 to X register 8 and Y register 9, respectively. Next, dot drawing is performed with reference to the character dot configuration information. After dot drawing is completed, the contents of the X register 8 are incremented, for example. 1
After drawing a block, when drawing the next block, the contents of the Y register 9 are incremented, and the contents of the X register 8 are decremented. Therefore, as a register operation at the time of block switching, it is only necessary to change the contents of the Y register 9.

FIG. 7 is a diagram showing the order of dot drawing in the drawing example shown in FIG. From the first dot of the first block, the incrementer 11 sequentially calculates the X address, and after completing the address calculation for the last dot, the incrementer 13 performs only the calculation from Y+1→Y. At this time,
The X address remains unchanged. Therefore, the address of the dot directly above the dot position is found and the second
Block drawing address calculation starts. The x-coordinate of the dot should not change, and this method makes good use of this fact. Thereafter, up to the final dot position, the decrementer 12 executes X-1→X every time the drawing address calculation for each dot is completed. When drawing of the third block is defined, after the drawing address calculation for the position is executed, the calculation of Y+1→Y is executed, and thereafter, X+1→X is incremented by the incrementer 11 for each 1-dot drawing address calculation. executed by. That is, the selection of the calculations X+1→X and X-1→X is made every drawing of one block. In this way, in the method of this embodiment, address calculation is performed continuously by writing with one stroke.

Next, an example of the operation for actually drawing on the video memory using the drawing address calculated by this method will be explained with reference to FIG. First, CPU10
transfers the x and y addresses of the drawing start point to the X and Y registers 8 and 9, respectively. As described in connection with FIG. 8a, a portion of the contents of X register 8 and the contents of Y register 9 indicate word register B, and the remainder of the contents of X register 8 indicates the dot address. shown. Next, the CPU 10 sets information for one block of character data to be drawn in a pattern register (not shown in FIG. 10). In the method shown in FIG. 8, the contents of the pattern register are rotated so that the position of the least significant bit corresponds to the instruction of the dot address, but in the drawing method shown in FIG. (not shown in FIG. 10), and pointer data indicating the drawing start bit (in this example, the least significant bit) is set in the same register as shown in FIG. 9a. Then, as shown by "first dot" in FIG. 9b, the dot data pointed to by the pointer data is read out and the same dot data is drawn at the address of the video memory indicated by the dot address. The contents of the X register 8 are then incremented by one by the incrementer 11. Further, the pointer data is also incremented by one in a similar manner. The dot data pointed to by the increased pointer data is read out, and the same data is drawn at the address in the video memory indicated by the dot address. Thereafter, the same process is repeated until the drawing of the first block is completed. When the drawing of the first block is completed, only the contents of the Y register 9 are incremented by one, as shown as the "ninth dot" in FIG.
The contents of X register 8 and pointer register are unchanged. Then, information on the second block of character data is set in the pattern register, and drawing is started. After the drawing of the ninth dot is completed, the contents of the X register 8 and the pointer register are both decreased by one, and subsequent drawing is executed.

As described above, in the present invention, the increase and decrease operations for the contents of the X address are first changed every time the contents of the Y address change, so the required hardware is reduced and the address calculation processing speed is improved. be done.

Furthermore, when drawing a pattern in the same block by enlarging it vertically or horizontally, in the conventional example, the same pattern is reset every time drawing in one drawing direction is completed, and the pattern positioning operation is performed. I have to. This is because in the conventional example, the shift operation of the pattern register is repeated in order to extract data in the pattern register, and the original pattern at the start of drawing is not saved. However, in the present invention, when enlarging drawing, there is no need to reset a new pattern as long as the drawing is within the same block, and there is no need to perform positioning operations for pattern contents. A new pattern can be set when drawing in the same block is finished and moving to drawing a new block.

In the above-described embodiments of the present invention, the case where the drawing address calculation is executed from left to right and from bottom to top on the memory plane was taken up, but in other cases, for example, from right to left and from top to bottom. Needless to say, the same applies when drawing is executed to.

[Brief explanation of drawings]

1 and 2 are schematic diagrams of a conventional drawing method, FIG. 3 is a flowchart of the conventional method, and FIG. 4a is a flowchart of a drawing address calculation method according to an embodiment of the present invention.
Figure b is a hardware block diagram of the address register section, Figure 5 is a data diagram showing the configuration inside the word address register, Figure 6 is a conventional address transition diagram, and Figure 7 is an embodiment of the present invention. FIGS. 8a and 8b are address transition diagrams according to the conventional method and data transition diagrams for designating dots to be drawn, respectively. FIGS. 9a and 9b are respectively according to the method according to an embodiment of the present invention FIG. 10 is a hardware block diagram of a conventional address register section, showing a diagram of data in the register corresponding to the calculated drawing address and a data transition diagram for designating a drawing dot. 1, 8...X register, 3, 9...Y register, 2
...X' register, 4...Y' register, 6, 7, 11,
13...Incrementer, 12...Decrementer,
5,10...CPU.

Claims (1)

[Claims] 1. A first register for storing data indicating the X address of the drawing position, a second register for storing data indicating the Y address of the drawing position, and a first means for incrementing the contents of the first register by one. ,
a second means for decreasing the contents of the first register one by one; a third means for increasing or decreasing the contents of the second register one by one; means for respectively transferring data indicating the X and Y addresses, and switching between increasing the contents of the first register by the first means and decreasing the contents of the first register by the second means. A drawing address calculation method characterized in that the calculation is performed every time the contents of the second register change by the third means.