JPH03196379A - Drawing calculation processing unit - Google Patents

Abstract

PURPOSE:To increase the drawing speed by providing two flag registers and leaving the state of a status flag for judging information regarding a dot generated on the last scanning line of the same straight line in a 2nd flag register when the area of part between two given straight lines is filled. CONSTITUTION:The two flag registers are provided and the contents of the 1st flag register 16 are transferred to and stored in the 2nd flag register 17 before the contents of the 1st flag register 16 are updated by performing arithmetic regarding a new dot generation point by an arithmetic means 13. Therefore, the status flag for grasping the information (e.g. cumulative error) regarding the last dot generated on the 1st straight line is left in the 2nd flag register 17. Consequently, the information regarding the last dot on the same straight line can easily and accurately be grasped only by referring to the 2nd flag register 17 to fill the area of part between the two straight lines at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a method of forming dots for each scan line on a dot pattern forming surface in which dot generation points are arranged in a matrix, for example in the rask scan method of CRT. The present invention relates to a drawing arithmetic processing device for generating and drawing figures, and particularly to a device suitable for performing high-speed filling processing between two given straight lines.

[Conventional technology]

In recent years, general-purpose microcomputers have come to be used as this type of drawing arithmetic processing device. The central processing unit (CPU) of a general-purpose microcomputer usually has an arithmetic unit (ALU), an accumulator (ACC) that temporarily holds the calculation results of the second ALU, and a status flag such as a carry that occurs as a result of the calculation. It has a flag register to This flag register indicates the status of the operation result (sign, presence or absence of carry, etc.).
In the calculation of the next step, U will not be able to perform the calculation according to the program unless the flag generated as a result of the calculation of the previous step is input from the flag register.

By the way, as a frequently performed task in the drawing process, there is a task of drawing two straight lines and filling in the space between the two straight lines. This work can be done, for example, as shown in Figure 3.
For each scan line in the rask scan direction (horizontal direction), the first straight line is drawn.

A first step of calculating the position of the dot generation point corresponding to the second straight line L2, a second step of calculating the position of the dot generation point corresponding to the second straight line L2, and a second step of calculating the position of the dot generation point corresponding to the second straight line L2. This is a process of repeating three steps: (1) and (3) generating dots at all dot generating points between them.

For the generation of each straight line, , L2, typically r Bresen
A method called "Ham's line drawing algorithm" is used. Regarding this r Bresenham's line drawing algorithm, please refer to the magazine rP published by Graphic Processing Information Center.
IXELJ NO. 11, pages 101 to 107, but to briefly explain with reference to FIG. 4, for example, a straight line whose slope with respect to the X axis is smaller than 456! When drawing a fixed dot Do(X
+, yI), the point DI (X
+ +1. yI) and a point Dz (x+ +1°yI+1) moved by one in the X-axis direction and the Y-axis direction, respectively, calculate the errors between these points D+-Di and the ideal straight line l, and calculate the error. The smaller point is determined as the drawing point and a dot is generated there. Do the same and make a straight line! Form a dot pattern to express

This operation is performed using only integer values.
This is Bresenham's line drawing algorithm J.

[Problem to be solved by the invention]

When filling in between two straight lines as explained in Figure 3 using Dr. Bresenham's line drawing algorithm, in order to generate dots corresponding to the straight lines L, In each of L+ and Lx,
The next dot cannot be generated unless there is information regarding the previous dot (for example, cumulative error, etc.). For example, in FIG. 3, in order to generate dot C along a straight line, the dot I-a just before the same straight line must be
information is needed.

However, in the filling operation between these two straight lines, by repeating the three steps described above, after calculating the dot a of the straight line L1, the calculation moves to the dot b of the straight line L2, and the calculation of the dot b of the straight line L1 At the time when the calculation for determining the generation position of dot C is performed, the contents of the flag register at the time of the calculation performed when generating dot A have disappeared. For this reason, in systems using conventional microcomputers, the information necessary to calculate the location of the dot C is stored in a memory separate from the CPU and read out for use. , dora) It is necessary to provide a special step to determine the state of the calculation result obtained when a occurs without using a flag register, and as a result, there is a problem that the overall drawing speed becomes slower. there were.

SUMMARY OF THE INVENTION Therefore, the present invention aims to solve the above-mentioned problems and provide a drawing arithmetic processing device that can fill in the space between two given straight lines at a higher speed than conventional drawing arithmetic processing devices. This is the issue to be addressed.

[Means to solve the problem]

The drawing arithmetic processing device according to the present invention for solving the above problems has a dot pattern forming surface (for example, a dot pattern formed in a bitmap memory 6) in which dot generation points are arranged in a matrix, as shown in FIG. (It may be a virtual concept.) In a drawing arithmetic processing device for drawing a figure by generating dots for each scan line, =
5= Calculating means 13 for calculating the positions of the points of occurrence of dots corresponding to the two straight lines for each scan line when performing the process of filling in the space between the two given straight lines; and the calculating means. When the calculation regarding one dot generation point is completed in step 13, the first flag register 16 stores the status flag recorded as a result of the calculation, and the calculation means 13 executes the calculation regarding the next dot generation point. a second flag register 17 that captures and stores the contents of the first flag register 16 before execution;
2 corresponding to the two straight lines on the two scan lines
The dot generating means (for example, the filling circuit 5 of the embodiment) generates dots at one dot generating point and all the dot generating points existing therebetween.

[Effect]

In the drawing arithmetic processing device of the present invention, two flag registers are provided, and before the contents of the first flag register 16 are updated by the arithmetic means 13 performing an operation regarding a new dot generation point, the contents of the first flag register 16 are updated. 1 flag register 1
6 is transferred to the second flag register 17 and stored therein.

Therefore, in the task of filling in the space between two given straight lines,
After performing calculations to determine the position of the dot generation point corresponding to the first straight line, calculations are performed to determine the position of the dot generation point corresponding to the second straight line, and then again corresponding to the first straight line. When performing calculations to find the position of the dot generation point, information regarding the dot generated one line before the first straight line (
For example, a status flag remains in the second flag register 17 for ascertaining cumulative errors, etc.).

Therefore, in the present invention, the second flag register 1
By simply referring to 7, information regarding the previous dot on the same straight line can be easily and accurately grasped.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings.

FIG. 1 is a block diagram showing the configuration of a drawing arithmetic processing device according to an embodiment of the present invention.

This drawing arithmetic processing device includes a straight line generation circuit 1, a clock generator 2 that supplies clock signals to the straight line generation circuit 1, and a filling circuit 5. The straight line generation circuit 1 and the filling circuit 5 are connected to a data bus 3 and an address bus. 4 to the bitmap memo I76. Although not shown, a program memory and other control devices such as a system controller are connected to the data bus 3 and address bus 4.

As shown in the figure, the straight line generation circuit 1 includes an instruction register 11, an instruction decoder/control circuit 12, an arithmetic unit (ALU) 13,
Data register (DR) 14, accumulator (ACC
) 15, first flag register 16, second flag register 17 and gate circuit 18.19.20.21.22
．． It consists of a microprocessor with 23.

An instruction read from a program memory (not shown) is temporarily held in an instruction register 11, and an operation part of the instruction is sent to an instruction decoder/control circuit 12 to be decoded. The instruction decoder/control circuit 12 sends various gate signals synchronized with the clock signal from the clock generator 2 to the gate 1 according to the contents of the decoded instruction code.
8 to 23, and generates various control signals and sends them to each section. Further, the arithmetic instruction decoded by the instruction decoder/control circuit 12 is sent to the ALU 13, where a predetermined arithmetic operation is executed.

The filling circuit 5 is configured in substantially the same manner as the above-described straight line generation circuit 1, and includes an instruction register, an ALU, and the like. However, only one flag register is sufficient. Therefore, this filling circuit 5 can be constructed by a conventional general-purpose microprocessor.

Next, a procedure for performing a filling operation between two straight lines using the drawing arithmetic processing device configured as described above will be described with reference to the flowcharts shown in FIGS. 2A and 2B.

Figure 2A shows the basic steps for filling in between two straight lines. For example, as shown in Figure 3,
When filling in the space between the straight lines LL and L2, first, the ALU 13 of the straight line generation circuit 1 in FIG. Do it (Step 1). The status flag generated as a result of this operation is stored in the first flag register 16.

Next, the ALU 13 of the straight line generation circuit 1 performs calculations to determine the position of the starting point (drag) b of the second straight line L2 on the same scan line (step 2). The status flag resulting from the calculation to find the position of the driver +-b is also stored in the first flag register 16, but before executing this calculation, the status flag is stored in the first flag register 16. The contents are taken into the second flag register 17 and stored.

The information regarding the dot generation point obtained by the ALU 13 of the straight line generation circuit engineer in steps 1 and 2 above is as follows:
The signal is supplied to the filling circuit 5 in FIG. Then, based on the information sent from the ALU 13 of the straight line generation circuit 1, the filling circuit 5 generates dots at both starting points a and b and all dot generation points existing between them (step 3). . Specifically, dot generation, that is, filling, by the filling circuit 5 is performed by logically inverting the bits corresponding to both starting points dots a and b in the bitmap memory 6, and all bits existing between them. .

When the filling operation on the first scan line is completed, the scan line is shifted by one (step 4), and the filling operation on the second scan line is performed.

FIG. 2B shows a subroutine for dot position calculation processing for performing the filling operation (steps 5 and 6) on the scan lines after the second scan line.

1 2 In this dot position calculation process, for example, when generating a dot c on the first straight line (step 5), first, the straight line generated on the previous scan line,
Data regarding dot a (for example, cumulative error value, etc.)
is read from the data register (DR) 14 in FIG. 1 and supplied to the ALUI 3.

The ALU 13 stores this data and the second flag register 17.
Accurate information regarding dot a is obtained from the flag state stored in dot a. At this time, the second flag register 17 stores the status flag when the ALU 13 performs the calculation on the dot a, so by supplying the stored contents of the second flag register 17 to the ALU 13, Regarding the flag, the ALU 13 is in the state immediately after generating a), as if it were continuously in the same straight line,
It will appear as if the above dot is generated.

Then, via the gate 22, the first flag register 1
The contents of 6 (that is, the flag state when performing the calculation regarding dot b of the second straight line L2) are stored in the second flag register 1.
Incorporated into 7.

Next, the calculations necessary to generate dot C are carried out by the ALU.
At this time, the contents of the first flag register 16 are updated.

Flow then returns to the main routine of FIG. 2A.

Exactly the same process is performed in step 6 for generating dots on the second straight line L2. For example, when generating a dot ld, data regarding the previous dot b is read out, and this data and Dora) ALU13 regarding b
Accurate information regarding t)b can be obtained from the second flag register 17, which stores the flag state of the result of the operation performed by .

Next, based on the information regarding the dot generation points obtained in step 5.6 above, the filling circuit 5 performs the following steps.
Dots are generated at the two dots c and d and at all dot generation points between them.

Next, it is determined whether the scan line is the last scan line (step 8), and if it is not the last scan line, the flow returns to step 4 to shift the scan line and start on the next scan line. Do the filling work.

In this way, dots e, f, etc. are sequentially obtained and the space between them is filled in.

In this way, in the drawing arithmetic processing device of this embodiment,
When generating dots other than a and b at the starting end of each straight line, , L, by supplying the stored contents of the second flag register 17 instead of the first flag register 16 to the ALU 13, Information regarding the previous dot on each straight line L+ and L2 can be accurately grasped. Therefore, for example, it is possible to perform arithmetic processing to determine the position of the dot generation point using only the registers in the processor, and even in that case, a special step is required to determine the information of the result of the calculation. does not require. Therefore, compared to this type of conventional drawing arithmetic processing device using a general-purpose microcomputer, filling processing between two straight lines can be performed at high speed.

Note that the embodiment described above is based on the C
Although this is a drawing arithmetic processing device for RT, the drawing arithmetic processing device of the present invention can be applied to all kinds of other dot plotters, printers, displays, etc.

Furthermore, the "dot pattern forming surface" referred to in the present invention does not need to actually exist, and may be a virtual concept developed in, for example, a bitmap memory.

Further, when the present invention is applied to a display device such as a liquid crystal display, each pixel of the display device can be regarded as one dot and the present invention can be applied.

〔Effect of the invention〕

In the drawing arithmetic processing device of the present invention, two flag registers are provided, and when performing the process of filling in between two given straight lines, information regarding the dots generated on the scan line immediately before the same straight line is stored. The state of the status flag for judgment is left in the second flag register.

Therefore, by looking up this second flag register, we can easily and accurately obtain the information necessary to determine the position of the straight dot point on the scan line, and other special Since it is not necessary to provide the step, the overall drawing speed can be increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a drawing arithmetic processing device according to an embodiment of the present invention, FIGS. 2A and 2B are flowcharts showing the operation of the device in FIG. 1, and FIG. 3 is a filling between two straight lines. FIG. 4 is an explanatory diagram for explaining the work, and FIG. 4 is an explanatory diagram for explaining the method of generating straight lines. In addition, in the symbols used in the drawings, 1... Line generation circuit 2... Clock generator 5...
・・・ Filling circuit (dot generation means) 6 ・・・・・・
・ Bitmap memory 13 ・・ Arithmetic circuit (ALU) ・ Accumulator (ACC) ・
...First flag register ...Second flag register

Claims (1)

[Claims] In a drawing arithmetic processing device for drawing a figure by generating dots for each scan line on a dot pattern forming surface in which dot generation points are arranged in a matrix, when performing the filling process, a calculation means for calculating the positions of the dot generation points corresponding to the two straight lines for each scan line; and a calculation means for completing the calculation regarding one dot generation point in the calculation means. a first flag register that stores a status flag generated as a result of the operation; and a first flag register that captures and stores the contents of the first flag register before performing the operation regarding the next dot generation point in the calculation means. a second flag register to perform dot generation at two dot generation points corresponding to the two straight lines on one scan line and all dot generation points existing therebetween, determined based on the calculation result of the calculation means; A drawing arithmetic processing device comprising: dot generating means for generating dots.