JPH02299076A - Image data upside down system - Google Patents

Abstract

PURPOSE:To shorten the processing time by designating the access address of a memory by a DMA controller and inverting the bit array on a data bus by a bus inverting circuit. CONSTITUTION:When a DMA controller 4 is started in the intermemory transfer mode by a host CPU 1, image data read out from a storage memory 2 of an image to be inverted is written in an inverted image storage memory 3. At this time, the controller 4 indicates the read address of the memory 2 and the write address of the memory 3. A bus inverting circuit 5 normally connects the bit array on the data bus when the controller 4 reads out image data from the memory 2. The circuit 5 inverts and connects it when the controller 4 writes image data in the memory 3. Thus, image data is inverted at high speed and the processing time is short even when large image data is handled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for vertically inverting image data on a screen display of, for example, a personal computer.

[Prior Art] Conventionally, as a method for displaying image data upside down on a display device such as a personal computer, there is a method using a dedicated LSI for image data processing, or a method using software control.

[Problem to be solved by the invention] The conventional method described above has the following drawbacks.

In other words, like the former, a dedicated L for image data processing is used.
When SI is used, the hardware becomes complicated and the amount of hardware increases, resulting in an unavoidable increase in cost.

On the other hand, in the case of software control like the latter, a long execution time is required to process the image data, so there is a drawback that it takes a very long time when handling large image data.

[Means for Solving the Problems] The image vertical reversal method of the present invention has the following means.

a) an inverted image storage memory that holds image data; b) an inverted image storage memory that holds image data obtained by inverting the image data; and C) DMA transfer of image data from the inverted image storage memory to the inverted image storage memory. d) a bus inverting circuit that operates in response to a request of this DMA controller and is interposed in a data bus that connects this DMA controller with the to-be-inverted image storage memory and the inverted image storage memory;

[Operation] The DMA controller increments and instructs the read address to the inverted image storage memory, and decrements and instructs the write address to the inverted image storage memory, and the bus inversion circuit instructs the DMA
When a controller reads image data from an image memory to be inverted, the bit arrangement of a data bus is normally connected, and when writing image data from a DMA controller to an inverted image storage memory, the bit arrangement of the data bus is inverted and connected. Therefore, the image data held in the inverted image storage memory is transferred and stored in the inverted image storage memory in an upside-down state.

[Example] Next, the present invention will be explained with reference to the drawings.

The figure is a block diagram showing a part of the configuration of a personal computer to which an embodiment of the image data up-down inversion method of the present invention is applied.

1 is the host CPU. 2 is a display VRAM (video RAM) that typically holds image data to be displayed on a display device (not shown), and a to-be-inverted image storage memory that holds image data before being inverted ( (hereinafter referred to as inverted image memory),
A RAM 3 stores the image data after being inverted, and is hereinafter referred to as an inverted image storage memory.

4 transfers image data between the above-mentioned inverted image storage memory 2 and inverted image storage memory 3 to the host CPU.
DMA (Di
Recto 14es+ory Access) controller. Reference numeral 5 denotes a bus inverting circuit, and when the DMAC bus 6 is connected to the data bus 7 under the control of the DMA controller 4, the bit arrangement of the DMAC bus 6 is inverted and connected to the data bus 7. .

Next, the image data vertical inversion operation will be explained.

The host CPUI activates the DMA controller 4 in memory-to-memory transfer mode. Activated DMA controller 4
performs a DMA transfer. That is, the image data read from the inverted image storage memory 2 is written into the inverted image storage memory 3. At this time, the DMA controller 4 increments and specifies the read address for the inverted image storage memory 2 on the transfer source side. On the other hand, the write address for the inverted image storage memory 3 on the transfer destination side is decremented and specified.

During this DMA transfer, the DMA controller 4
When reading image data from the image storage memory 2 to be inverted, the bus inverting circuit 5 is disabled (unusable state) and the DMCA data bus 6 is switched to the data bus 7.
successfully connect to. That is, the connection is made without inverting the bit arrangement. On the other hand, when writing the image data read from the to-be-inverted image storage memory 2 to the inverted image storage memory 3, the bus inversion circuit 5 is enabled (usable state B) and the bit arrangement of the DMCA data bus 6 is inverted to the data bus 7. Connect in state.

Therefore, the image data held in the inverted image storage memory 2 is DMA-transferred to the inverted image memory 3 by the DMA controller 4, so that the address is in the opposite direction and the bit arrangement of the image data is inverted. The image is stored in the inverted image storage memory 3.

When the image data held in the inverted image storage memory 3 in this manner is sequentially transferred to a display device, the original image data will be displayed upside down.

In addition, although the above-mentioned embodiment explained a personal computer, this invention is not limited to a personal computer, and it goes without saying that this invention can be similarly applied to a computer having a similar display device. .

[Effects of the Invention] As explained above, according to the image up-down reversal method of the present invention, when image data is sequentially transferred and stored from the inverted image storage memory to the inverted image storage memory, the DMA controller performs the above two types of image reversal methods. By inverting the address for accessing the memory and inverting the bit arrangement of the data bus by the bus inversion circuit, image data can be inverted vertically at high speed. Further, it is only necessary to add a small amount of circuitry to the existing hardware of display devices in personal computers, etc., and there is no risk of an increase in cost unlike in the past.

[Brief explanation of drawings]

The figure is a block diagram showing a part of the configuration of a personal computer to which an embodiment of the image data up-down inversion method of the present invention is applied. 2... Inverted image storage memory, 3... Inverted image storage memory, 4... DMA controller, 5...
・Bus inversion circuit, 6...DMAC data bus, 7...
・Data bus.

Claims (1)

[Claims] An image data vertical inversion method for vertically inverting image data displayed on a display device, comprising: an inverted image storage memory that holds image data; and an image data obtained by inverting the image data. D of the image data from the inverted image storage memory to the inverted image storage memory.
A DMA controller that performs MA transfer, and a bus inverting circuit that operates in response to a request of this DMA controller and is interposed in a data bus that connects this DMA controller and an inverted image storage memory and an inverted image storage memory, The DMA controller increments and instructs the read address to the inverted image storage memory, and decrements and instructs the write address to the inverted image storage memory, and the bus inversion circuit instructs the DMA
When the controller reads image data from the image memory to be inverted, the bit arrangement of the data bus is connected normally, and when the DMA controller writes image data to the inverted image storage memory, the bit arrangement of the data bus is inverted and connected. An image data upside-down method featuring: