JPH0219467B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a graphic processing device such as a display device having a function of displaying a figure or a printing device having a function of printing a figure, and particularly relates to a figure processing device such as a display device having a function of displaying a figure or a printing device having a function of printing a figure. This invention relates to an image memory writing circuit that has an image memory that can write data in units of multiple bits (e.g., units of words or bytes) and units of 1 bit, and that performs processing such as filling in figures written in the image memory at high speed. .

(b) Prior Art and Problems In a graphic processing device that has an image memory for storing figures to be displayed or printed and a means for drawing figures in the image memory, conventionally, when writing figures to the image memory, a bit is used. If the figure is written in units and requires processing such as filling, unlike figures with many diagonal lines, the object to be written is a surface, so writing in bits will slow down the processing speed. That is, since the image memory is generally a one-dimensional memory in which figures are written or read by raster scanning, processing speed can be improved by writing or reading horizontal lines and planes in units of words or bytes. However, graphics have many diagonal lines, and cannot be processed in units of words or bytes, so all data is written or read in units of bits. Therefore, processing such as filling, which should be performed on a surface, has the disadvantage of lowering efficiency.

(c) Object of the invention In order to eliminate the above-mentioned drawbacks, the object of the present invention is to perform figure filling processing, etc. by simultaneously writing multiple bits to a figure stored in an image memory that can be accessed in units of one bit and in units of multiple bits. When writing a figure, the part written outside the memory boundary (the boundary on the memory accessed in word units or byte units) on the image memory where the line segment representing the figure is stored is written in bit units, The object of the present invention is to provide an image memory writing circuit that improves the speed of graphic filling processing by writing the portion written within the memory boundary in word units or byte units.

(d) Structure of the Invention An image memory writing circuit that performs writing processing of graphic data to an image memory capable of writing processing in units of 1 bit and simultaneous writing processing for all bits within a predetermined address boundary. , a 1-bit unit write circuit that writes to the image memory in 1-bit units, a multiple-bit unit write circuit that simultaneously writes all bits within a predetermined address boundary to the image memory, and graphic data to be written. means for determining whether or not the partial area satisfies all bits within a predetermined address boundary of the image memory; a switching circuit for selectively operating a unit write circuit, and when the partial area fills all bits within a predetermined address boundary of the image memory, writing is performed simultaneously by the plurality of bit unit write circuits. If the partial area does not fill all the bits within a predetermined address boundary of the image memory, the 1-bit unit write circuit writes in 1-bit units.

(e) Embodiments of the invention FIG. 1 is a diagram illustrating the principle of the invention. It is assumed that triangular image data 2 is stored in the image memory 1. The dotted line ranges a, b, and c of the image memory 1 are memory boundary ranges, and have, for example, 16-bit intervals in word units. Now raster scan line 3
is scanning image data 2, the amount of data of image data 2 included in the range indicated by a, from the starting point f of image data 2 until it reaches the memory boundary g of image memory 1, is one word. Since it is not available, it is necessary to write one bit at a time. After reaching the memory boundary, that is, the range indicated by b is written in word units. When it enters the range shown by c, image data 2
Since the amount of data is less than one word, it must be written in bits. By repeating the above operations from point d to point e of image data 2, it is possible to completely fill in image data 2. Filling includes processing such as writing "1" for all cases and writing "1" and "0" for every chance occurrence.

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention. The microprocessor 5 sets the starting point address shown in FIG. The start point address set in the counter 6 is then sent to the image memory 1 as the write start address of the image data 2.
The lower four bits of the starting point address set in the counter 7 are used to detect memory boundaries. Microprocessor 5 processes image data 2
To calculate the number of bits from the memory boundary to the start point and set the lower 4 bits, if you add the value of counter 7 every time you write 1 bit of data, the value of counter 7 will all be "1". 1, it indicates that the address has reached the memory boundary of the image memory 1 shown in FIG. The counter 7 sends a carry signal to the flip-flop 12 when all the counted values become "1". Therefore, flip-flop 12 is set by the carry signal.

The microprocessor 5 sends data to be written into the image memory 1 to a bit unit write circuit 14 and a word unit write circuit 15. Bit unit write circuit 1
4 until flip-flop 12 is set.
Since the output of the NOT circuit 13 is "1", the write data instructed by the microprocessor 5 is sent to the image memory 1 one bit at a time, and
One bit at a time is written sequentially from the write start address. The word unit write circuit 15 is a flip-flop 1.
It does not work because the output of 2 is “0”. When the flip-flop 12 is set as described above, the output of the NOT circuit 13 becomes "0", so the bit unit write circuit 14 stops operating, and the word unit write circuit 1
5 sends the write data sent from the microprocessor 5 to the image memory 1 word by word, and the bit unit write circuit 14 sequentially writes the write data word by word following the written data.

The microprocessor 5 calculates the length from the first encountered memory boundary of the image memory 1 of each raster scan line, as shown in FIG. 1g, to the end point of the image data 2 of each raster scan line, as shown in FIG. 1h. , that is, the length from g to h is divided into counters 8 and 9 and set. The upper bits excluding the lower 4 bits are set in the counter 8, and the lower 4 bits are set in the counter 9. The counter 8 is used to detect the range in which each raster scanning line can be written into the image memory 1 word by word. The counter 8 is decremented each time the word unit write circuit 15 writes one word. When all the values of the counter 8 become "0", the output of the OR circuit 10 becomes "0", and therefore the output of the NOT circuit 11 becomes "1" and resets the flip-flop 12. Therefore, the word unit write circuit 15 stops and the NOT circuit 1
3 becomes "1", the bit-by-bit write circuit 14 becomes operational, and writes the write data in 1-bit units to the word-by-word write circuit 15 of the image memory 1.
Write following the data written by. The counter 9 decrements every time one bit of write data is written. When the counter 9 becomes all "0", the microprocessor 5 determines that data writing on one raster scanning line is completed and starts the next operation.

(f) Effects of the Invention As explained above, the present invention switches between bit-by-bit writing and plural-byte writing, so that processing such as filling in figures can be performed at high speed.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, and FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention. 1 is an image memory, 5 is a microprocessor,
6, 7, 8, and 9 are counters, 12 is a flip-flop, 14 is a bit unit write circuit, and 15 is a word unit write circuit.

Claims (1)

[Scope of Claims] 1. An image memory writing circuit that performs writing processing of graphic data to an image memory capable of writing processing in units of 1 bit and simultaneous writing processing for all bits within a predetermined address boundary. Then, write to the image memory in units of 1 bit.
a bit-by-bit write circuit; a multiple-bit-by-bit write circuit for simultaneously writing all bits within a predetermined address boundary to the image memory; means for determining whether or not all bits within the boundary are filled; and a switching circuit for selectively operating the 1-bit unit write circuit and the plurality of bit unit write circuits based on the determination result of the determination means. Preparation: If the partial area fills all bits within a predetermined address boundary of the image memory, writing is performed simultaneously by the plurality of bit unit write circuits, and the partial area fills a predetermined address boundary of the image memory. An image memory write circuit characterized in that when all bits within an address boundary are not filled, the 1-bit unit write circuit performs writing in 1-bit units.