JPS638694A - Raster computation control system for bit map display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a bitmap display method, and particularly to a bitmap display method.

Related to raster calculation control method.

In the conventional technology bitmap display method, when transferring a certain rectangular area A in the display memory to another area B, it is possible to perform a certain pool algebraic operation on the memory data of the transfer destination, that is, the original data of area B. It performs circular display and overlapping display of multiple areas. In this case, the transfer is generally performed word by word, with the next three sequences being one cycle, and repeated for the data of the transfer source area A.

■ Read and store 1 word of data in area A.

■ Read and store 1 word of data in area B.

■, Calculate the stored data of areas A and B.

(2) Write the calculation result to area B.

Problems to be Solved by the Invention In the above-mentioned conventional raster arithmetic system, the transfer of every l word is always executed in two operations.

However, depending on the data in area A, the data in area B, and the type of operation, there may be words in which the original data in destination area B and the operation result, that is, the update data to area B, match. be. In this case, there is no need to write update data into area B. Therefore, the conventional method has the disadvantage that time is wasted on this meaningless operation.

The present invention has been made in view of the above-mentioned conventional circumstances, and
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a new raster arithmetic control system for pit map displays which makes it possible to eliminate the above-mentioned drawbacks inherent in the prior art.

Means for Solving the Problems In order to achieve the above object, the raster arithmetic control method according to the present invention includes a comparison means for comparing the original data at the transfer destination and the transferred data after the raster arithmetic operation, It is characterized in that it is switched whether or not to execute the data write operation to the transfer destination depending on the comparison result of the comparison means. That is, if both data match, data writing to the transfer destination is omitted, and data writing is executed only if both data do not match.

EXAMPLE Below, a preferred embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an operation flowchart showing the operation of the state control circuit octopus in FIG.

Next, the circuit configuration of this embodiment will be explained based on FIG. An embodiment of the present invention includes a data register 1 for storing transfer data, a data register 1 for storing transfer destination data, a data register 1 for storing the operation result of ALU J, and a comparator! and a state control circuit octopus.

The data input/output terminal 6 is connected to the input of the data register 1, the input of the data register 1, and the output of the data register 1 by a data line 7. One input of ALU j is connected to the output of data register l by a connection line t, and the other input is connected to the output of data register l by a connection line ? Connected with The output of ALo, 7 is connected by a connection line 10 to the input of the data register and one input of comparator j.

The other input of the comparator 3 is connected to the output of the data resistor via a connection line D. The output of the comparator S is grounded to the state control circuit / through the connection line //.

Next, the operation of this embodiment will be explained based on FIGS. 1, 2, and 3. FIG. 3 is a diagram showing an example of an operation when a rectangular area of a bitmap display type display memory is transferred to another area using an embodiment of the present invention. In the example shown in FIG. 3, data in a rectangular area A of %t bits Xt bits is cut out horizontally on the screen in units of l words (t bits), and transferred j times across the area in units of l words (t bits). During this transfer, an OR operation is performed with the original data of the transfer destination area B for each l word. The operation when the transfer example shown in FIG. 3 is executed in the embodiment shown in FIG. 7 will be described below.

First, the first seven words of area A of the display memory are read under the control of the state control circuit/2. The data is applied to the data input/output terminal 6 and stored in the data register/ via the connection line. This is the operating state of Sl shown in FIG. Next, the first l words of area B of the display memory are read. This data is also transmitted to the data input/output terminal 6.
and stored in the data register via the connection line. This is the zero-order operating state of $- in Figure 1,
The data in the data register / and the data in the data register are subjected to an OR operation, and the result of the operation is stored in the data register.
, 7 is connected to the output of the data receiver that stores the original data of the transfer destination C area B) using a comparator! Compare at. This comparator! operates so that the output becomes /'' when the two inputs are equal.Here, the state control circuit checks the output of the comparator via the connection line // (this is the operating state shown in Figure 1). ), if the output of comparator j is "O", it is written to the first l word position of the booter B area of the data register.
This is the operating state of u. On the other hand, comparator! The output of “
/”, the data write operation to the display memory of the data register, that is, the operation state of Ss is omitted. This means that the l cycle operation for the first l word is completed. Similarly, the above operation is repeated until the data in area A is completed (5 times in the case of FIG. 3).

To summarize these series of operations based on Figure 2, if the original data (data register 2) of the transfer destination (area B) and the output after raster operation (output of ALU, ?) match, Sl- The cycle progresses from 4S Yu to S, 7, and Sl
The processing of 7 words is completed at 3 timings of −8 and y.

On the other hand, if the two do not match, V ko is Sl- + S ko → S3
→Su and the cycle progresses to 1, and the processing of the / word ends at the da timing of Sl-341.

FIG. 9 shows details of changes in data during the operation of FIG. 3. As is clear from the figure, the data in the shaded area shown after execution is the updated data (II word), and the data in the area without the hatching (II word) is updated because the data before and after the change are the same. This is data that did not exist.

Therefore, the total time required to transfer this rectangular area of g pits xr bits is K as follows.

3 (timing/word) × gu (word) + lI (timing/word) The total time required to transfer a rectangular area of l bits x r bits is as follows.

da (timing/word) This means that this has been improved.

As described in detail, according to the present invention, the original data at the transfer destination and the transfer data after raster operation are compared, and if the two match, that is, there is no need to update the data at the transfer destination. In some cases, by omitting the data write operation to the transfer destination, the effect of apparently improving the data transfer speed in raster calculation control can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing an embodiment of the invention, FIG. 1 is an operation flowchart showing the operation of the state control circuit in FIG. 1, and FIG. 3 shows rectangular transfer of display memory using the invention. A conceptual diagram of the operation when executed, the reference figure is a detailed diagram of the change in data in FIG. 3. /, 2. 'I...Register, J...ALU, y...
・Comparator, 6...Data input/output terminal %/:1・
... State control circuit moss permit applicant NEC Corporation agent Patent attorney Yuta Kumagai Figure 1 Figure 2 rotation! Transfer before the main stage (Fig. 3)

Claims (1)

[Claims] In a bitmap display system, when data in a rectangular area in the display memory is divided into multiple bits and transferred to another display area, the bit that performs pool algebraic operations with the memory data at the transfer destination and transfers the data. In raster arithmetic control on a map display type display, a comparison means is provided for comparing the original data at the transfer destination and the transfer data after raster arithmetic, and the data writing operation to the transfer destination is performed based on the comparison result of the comparison means. A bitmap display raster arithmetic control method characterized by switching whether to execute or not.