JPS61131033A - Control system of ring buffer - Google Patents

Abstract

PURPOSE:To control the overtaking of input data against output data so as to make output data highly reliable, by storing page control information together with page data in a ring buffer and controlling the input-output of the ring buffer by using the page control information. CONSTITUTION:A CPU 1 sends output data in lines to a printing device 2 and the data are written in corresponding areas of a ring device 2 and the data are written in corresponding areas of a ring buffer 22 after they are accepted by a register 21. A page control section 23 controls the output data in pages and page control information 221 which is not print-outputted at every page is written in an area corresponding to the said page of the ring buffer. An input-output data control section 25 controls the input and output of the ring buffer in accordance with the page control information and, therefore, even when overtaking of input data against output data takes place, the overtaking can be detected through the disturbance of the page information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control method for a ring buffer of an output device, and particularly to a control method for a ring buffer that outputs data page by page.

[Conventional technology]

BACKGROUND ART Printing devices are widely used that store data sent line by line from a central processing unit in a data buffer, and when one page's worth of data is accumulated in the data buffer, print is triggered by this. This printing apparatus employs a ring buffer having a capacity for n pages, since the processing speed is slow when outputting data with consecutive pages.

In a printing device using this ring buffer, data management of the ring buffer is important. On the other hand, when conventional printing devices input data into the ring buffer, they use the output pointer to check the empty area of the ring buffer.
A method is adopted in which data is input into this empty area. However, if for some reason data input is overtaken, such as inputting data into a non-empty area, the printing device will print random data. Moreover, this printing continues from then on, and there is a problem in that errors occur in the output print data, causing problems.

[Problem that the invention seeks to solve]

In view of the above-mentioned conventional situation, the present invention provides a ring buffer control method for managing overtaking of human data based on the page management information, particularly for storing page management information in the ring buffer, and output data. The aim is to improve the reliability of the system.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention stores data sent line by line in a ring buffer having a capacity of 0 pages, and outputs page by page from this ring buffer. The device includes a page management unit that manages pages of data stored in a ring buffer, and a writing unit that writes page information to the ring buffer, and controls input/output of the ring buffer based on page information of the ring buffer. This is done by the buffer management method.

[Effect]

The above-mentioned ring buffer has page information written together with data, and controls the input/output of data to the ring buffer based on this page information to improve page management accuracy and manage overtaking. This improves the reliability of data.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a main part of an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the present invention. The central processing unit l sends character data line by line to the printing device 2.

The printing device 2 receives this character data in the register 21 and transfers the character data to the ring buffer 22. The page management section 23 manages the character data input to the ring buffer on a page-by-page basis, and sends a signal to the page information writing section 24 for each page.

The page information writing unit 24 stores the write information at the leading address of the data. Written information, for example, page number 221' is information that is not printed during printing.

The input/output data control unit 25 controls input/output based on the page number 221 of the ring buffer 22.

The above control operation will be explained with reference to FIG.

When the printing device 2 receives character data from the central processing unit 1, it performs initial settings. State (1) shown in FIG. Hereinafter, the states in FIG. 2 will be indicated by numbers in parentheses. In this initial setting, page number #1 of the write information described above is stored at the leading address of the ring buffer.

The character data is read from the register 21 and stored in the rolling buffer 22 (3). The input character data is 1
This continues until the page has been stored, and the page management unit 23 confirms that the storage for one page has been completed (4). ■When the page storage is completed, the page information writing section 24 operates and writes the next page information, that is, 112, into the ring buffer 22 (5).Furthermore, the page management section 23 writes the character data into the ring buffer 22 completely. The input/output control unit 25 detects whether writing has been performed (6) and detects whether input of character data is completed (7). When full writing is completed or input data is completed, the input/output control unit 25
The ring buffer outputs page by page (8), and the page management section 23 inputs character data page by page.

Although the above explanation has been made using a printing device, it goes without saying that the present invention can also be applied without any problem to a display device that displays character data on a screen-by-screen basis.

〔Effect of the invention〕

Now, as can be understood from the above explanation, in short, the present invention writes page information to a ring buffer, manages the ring buffer based on this page information, and detects the occurrence of overtaking by the disturbance of page information. The present invention is highly effective in obtaining normal output data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the present invention. In the figure, 1 is a central processing unit, 2 is a printing device, 22 is a ring buffer, 23 is a page management section, and 24 is a page information writing section.

Claims (1)

[Claims] In an output device that stores data sent line by line in a ring buffer having a capacity of n pages and outputs page by page from the ring buffer, the output device manages pages of data stored in the ring buffer. comprising a page management unit and a writing unit that writes page information to the ring buffer,
A ring buffer control method characterized in that input/output of the ring buffer is controlled based on page information of the ring buffer.