JPH04278652A - Graphic drawing device and its memory access system - Google Patents

Abstract

PURPOSE:To increase the drawing speed of an oblique line or a vertical line where the address of data on each dot forming a segment varies for each dot. CONSTITUTION:A straight line generator 1 calculates the dot data covering the start point through the end point of a straight line and sends the data to a memory control means 2. An address control part 5 of the means 2 controls the address data stored in a frame memory 8 consisting of an odd number memory 9 and an even number memory 10 and then controls the write the dot data having its changed address into the memory 10 from the memory 9 via an address converter 7. The dot data included in the next boundary range can be stored in a pre-buffer memory 4 of the means 2 even in a write state of the data. Then the dot data are written into the memory 9 via an odd number memory 5 if the Y coordinates of the dot data are equal to an odd number and then into the memory 10 via an even number buffer memory 6 if the Y coordinates are equal to an even number respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic drawing device for drawing graphic data on a frame memory and its memory access method.

0002

2. Description of the Related Art Conventionally, when performing straight line drawing processing in a graphics processing device that draws graphics data on a frame memory, addresses are separated by a certain boundary unit of data (for example, 1 byte) in the frame memory space. Every time dot data, which is pixel data, from the linear generator crosses this boundary, one byte of data is written to the frame memory, and during writing, the linear generator writes the data after the next dot data to the next byte. A drawing process is used in which the dot data is stored in advance up to the boundary range of , and immediately after the memory access is completed, the stored 1-byte worth of dot data is written into the frame memory, thereby performing drawing processing in a pipeline format.

[0003] In this method, dot data is written to the frame memory in byte units, so there is no need to write to the frame memory every time the linear generator calculates one dot, and the number of memory accesses can be reduced. . Particularly when drawing a line segment in the horizontal direction, the address of one byte of dot data does not change, so it has the advantage of being able to draw at high speed.

0004

However, in such a conventional method, when drawing a diagonal line forming an angle of 45°≦θ≦90° with respect to the X-axis direction as shown in FIG. As shown in Figure 5, since the vertical direction (Y direction) boundary unit, that is, the address changes for each dot, it is necessary to access the frame memory every time the linear generator calculates one dot, and the linear generator calculates the next dot. Although the calculation of dots can proceed, it has the disadvantage that it is inefficient because it has to stop until the memory access is completed.

The present invention has been made in view of the above points, and an object of the present invention is to enable efficient and high-speed drawing of diagonal lines as described above.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a graphic drawing device that draws graphic data on a frame memory, in which the frame memory is composed of a plurality of memories, and a straight line is formed. a linear generator that generates each pixel data and an address on the frame memory corresponding to each pixel data; a memory control means that controls writing of the pixel data to the frame memory according to the address; and an output from the memory control means. address conversion means for converting an address into an address corresponding to address mapping of the frame memory and sequentially outputting the converted address to a plurality of memories constituting the frame memory; the plurality of pixel data forming a straight line generated by the straight line generator; can be written in parallel to a plurality of memories constituting the frame memory.

Further, in the above-mentioned graphic drawing device, as shown in the block diagram of FIG. It has a pre-buffer memory 4 that temporarily stores pixel data, and an odd buffer memory 5 and an even buffer memory 6 that separate and hold each pixel data into data whose Y coordinate is an odd number and data whose Y coordinate is an even number. It is preferable that each pixel data held in the buffer memory 5 and the even buffer memory 6 can be written in parallel to the two memories forming the frame memory 8, respectively.

Furthermore, in such a graphic drawing device, each pixel data forming a straight line generated by a straight line generator is sequentially allocated to a plurality of memories constituting a frame memory according to its address information, and the pixel data forming a straight line generated by a straight line generator is allocated in parallel to the plurality of memories. The present invention also provides a memory access method characterized in that the adjacent pixel data are accessed and written to different memories.

[0009]

[Operation] According to the graphic drawing device and its memory access method according to the present invention, pixel data (dot data) forming a straight line generated by a straight line generator can be written in parallel to a plurality of memories constituting a frame memory. Therefore, even when drawing a diagonal line where the address on the frame memory changes for each dot, the line generator can calculate the next dot without waiting for the memory access to finish, drawing efficiently and at high speed. can do.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a graphic drawing device showing an embodiment of the present invention. This drawing device is
It is composed of a linear generator 1, a memory control means 2, an address converter 7, and a frame memory 8.

The straight line generator 1 calculates and generates dot data, which is pixel data from the start point to the end point of the straight line, and an address on the frame memory 8 corresponding to each dot data, and sends it to the memory control means 2. Memory control means 2
1 controls the writing of dot data into the frame memory 8 based on the address generated by the linear generator 1, and includes an address control section 3, a pre-buffer memory 4 for temporarily loading dot data, an odd-number buffer memory 5, and It is composed of an even number buffer memory 6.

The frame memory 8 is composed of a plurality of memories whose addresses are separated by 1 byte, ie, an odd memory 9 and an even memory 10 in this example, as in the conventional example shown in FIG.

The address control section 3 of the memory control means 2
Address data in the frame memory 8 is managed, and in this example, when dot data crosses a 1-byte boundary, that is, when the dots forming a straight line move from address n to address (n+1) in FIG. Control is performed to write dot data at address n into frame memory 8 via address converter 7.

The address converter 7 determines whether the Y coordinate of the dot data to be written is an odd number or an even number, and if it is an odd number, it is stored in an odd number memory 9 of the frame memory 8, and if it is an even number, it is stored in an even number memory. 10 so that data can be written to the corresponding memory.

Furthermore, even when data is being written to the odd memory 9 or the even memory 10 of the frame memory 8, the memory control means 2 controls the dot progress information (dot data) from the linear generator 1 within the range of the next byte boundary. (In this case, address (n+1)) can be first loaded into the pre-buffer memory 4 and stored. Furthermore, depending on whether the Y coordinate of the dot data is an odd number or an even number, if it is an odd number, it is stored in the odd number buffer memory 5, and if it is an even number, it is stored in the even number buffer memory 6.
are loaded alternately.

Under address control by the address converter 7, the data in the odd buffer memory 5 is transferred to the odd memory 9, and the data in the even buffer memory 6 is transferred to the even memory 1.
0 respectively. At this time, dot data at the next address is loaded into the pre-buffer memory 4. By repeating such operations, a series of dot data forming a straight line is alternately written into the odd memory 9 and the even memory 10 of the frame memory 8.

Next, the operation and effect when drawing a straight line L forming an angle of θ=45° with respect to the X axis as shown in FIG. 2 will be explained using this embodiment. FIG. 3 shows the structure of the frame memory 8, with the white part showing the odd number memory 9 and the hatched part showing the even number memory 10.

When the starting point coordinate information (dot data) (4, 4) is output from the straight line generator 1, the memory control means 2 loads it into the pre-buffer memory 4. When the linear generator 1 outputs the coordinate information (5, 5) of the next dot, the memory control means 2 outputs the data in the pre-buffer memory 4 (here, bit 4) because the data boundary exceeds the 1-byte range. is ON) is set in the next stage buffer memory and written into the frame memory 8, and at the same time, the coordinate information (5, 5) of the next dot is loaded into the pre-buffer memory 4.

Here, since the Y coordinate of the start point data (4, 4) to be written to the frame memory 8 is an even number (4), the address converter 7 selects the even number memory 10, specifies its address A, and writes the start point data (4, 4) to the frame memory 8. The start point data loaded into the buffer memory 4 is written to address A of the even memory 10 via the even buffer memory 6.

Next, coordinate information (6, 6) is sent from the linear generator 1.
is output, the data boundary exceeds the 1-byte range as described above, so the data (5, 5) in the pre-buffer memory 4 is written to the frame memory 8, but this data (5, 5) ) has an odd Y coordinate (5), so the address converter 7 selects the odd memory 9 and specifies its address B, and transfers the data (5, 5) loaded into the pre-buffer memory 4 to the odd buffer memory. 5 to address B of the odd memory 9.

At the same time, the memory control means 2 loads the data (6, 6) into the pre-buffer memory 4 and accepts the input of the coordinate information (7, 7) of the next dot from the linear generator 1.

By repeating such operations, the line segment of the straight line L in FIG. 2 is moved from the starting point (4, 4) to the ending point (10
, 10) are sequentially written into the odd memory 9 and the even memory 10 constituting the frame memory 8 (adjacent dot data almost simultaneously) as shown in FIG. The timing sequence of the above operation is shown in FIG.

As described above, in this embodiment, the odd number memory 9 and the even number memory 10 constituting the frame memory 8 are accessed in parallel, and the data of two adjacent dots of each dot constituting a line segment is approximately stored. Can be written at the same time. Therefore, when drawing a diagonal line or a perpendicular line forming an angle of 45° to 90° with respect to the X-axis direction, the speed can be nearly twice as high as that of the conventional method.

Further, in this example, the frame memory is composed of two memories, but it may be composed of three or more memories. Note that when displaying a straight line drawn in frame memory on the display, dot data is read alternately from odd and even memories (if three or more memories are used, sequentially and cyclically from each memory). All you have to do is read it out and transfer it to the video memory.

[0025]

Effects of the Invention As explained above, according to the present invention, a straight line (45°≦θ≦ with respect to the
When drawing diagonal lines or vertical lines forming an angle of 90°, the drawing speed can be greatly increased and the drawing performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a graphic drawing device showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a line segment to be drawn.

[Fig. 3] Straight line L shown in Fig. 2 in the frame memory 8 of Fig. 1.
FIG. 2 is an explanatory diagram showing a state in which each dot data constituting the image has been written.

4 is a diagram showing a timing sequence of operations when drawing a straight line L in FIG. 2 by the graphic drawing device in FIG. 1; FIG.

FIG. 5 is an explanatory diagram showing the writing state of each dot data in the frame memory when the straight line L in FIG. 2 is drawn by a conventional graphic drawing device.

[Explanation of symbols]

1 Linear generator
2 Memory control means 3 Address control section
4 Pre-buffer memory 5 Odd buffer memory
6 Even number buffer memory 7 Address converter
8 Frame memory 9 Odd number memory
10 Even number memory

Claims (3)

[Claims] 1. A graphic drawing device that draws graphic data on a frame memory, wherein the frame memory is composed of a plurality of memories, and each pixel data forming a straight line and each pixel data corresponding to each pixel data are stored in the frame memory. a linear generator that generates an address; a memory control means that controls writing of the pixel data into the frame memory according to the address; and an address that is outputted from the memory control means and corresponds to address mapping of the frame memory address conversion means for sequentially outputting the pixel data generated by the straight line generator to the plurality of memories forming the frame memory; A figure drawing device characterized by being able to write in parallel. 2. The graphic drawing device according to claim 1, wherein the frame memory is comprised of two memories, and the memory control means includes a pre-buffer memory for temporarily storing pixel data generated by the linear generator; It has an odd number buffer memory and an even number buffer memory that hold each pixel data divided into data whose Y coordinate is an odd number and data whose Y coordinate is an even number, and each pixel data held in the odd number buffer memory and the even number buffer memory is A graphic drawing device characterized by being able to write in parallel to two memories constituting a frame memory. 3. In a graphic drawing device that draws graphic data on a frame memory, each pixel data forming a straight line generated by a straight line generator is sequentially allocated to a plurality of memories constituting the frame memory according to its address information, A memory access method characterized by accessing the plurality of memories in parallel and writing adjacent pixel data into different memories.