JP2522910B2 - Line buffer switching system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention uses a plurality of line buffers, decodes a run length code, and alternately stores one line of data in the line buffers for processing, for example, a facsimile. The present invention relates to an apparatus, and more particularly, to a line buffer switching method for storing first data in the line buffer.

A facsimile machine uses a so-called run length code composed of a series of variable length codes in order to transmit data in a time as short as possible. Also, after decoding this run length code, it is stored in the line buffer and processed.
A plurality of line buffers for continuously receiving the next data are provided, and when one line of data is stored, the line buffer is switched to store the data of the next line.

By the way, since this run-length code indicates data for one line, when transmitting the run-length code, a line end code (hereinafter referred to as EOL) is added to the beginning of the message at the start of transmission and is transmitted. EOL is added again after the data for one line, which is composed of a code indicating the run length. When indicating the end of a message, 6 EOLs are consecutive.

Therefore, the receiving side ignores the first EOL, stores the data obtained by decoding the run length code for one line in the line buffer, determines that the data reception for one line is completed from the next EOL, and switches the line buffer. Then, the next data is stored. When 6 EOLs are detected, it is determined that one telegram has ended.

The determination of line buffer switching is performed by EOL as described above, but since it is also added at the beginning of the telegram as described above, if this EOL is not ignored, the line buffer in which data is not stored will be switched, which is inconvenient. Occurs. Therefore, although the leading EOL is ignored as described above, it is desirable that the means for detecting that the leading EOL is simple.

[Conventional technology]

FIG. 2 is a block diagram of a circuit for explaining a conventional line buffer switching system.

The decoder 1 decodes the input run length code, that is, the code representing the white or black run length, and sends it to the intermediate register 2. The intermediate register 2 temporarily stores the decoded data in response to a load signal from a flip-flop 10 described later.

The decoder 1 sends a code detection signal to the AND circuit 11 simultaneously with the above decoding. At this time, since the terminal of the flip-flop 10 is "1", the output of the AND circuit 11 also becomes "1" and the flip-flop 10 is set. This results in a flip-flop
The terminal Q of 10 becomes "1", and the load signal is sent to the intermediate register 2 and the control unit 9.

The intermediate register 2 sends the stored data to the length counter 3 and the multiplexer 4, and the multiplexer 4 switches the data under the control of the control unit 9 every time one line of data is written in the line buffer 6 or 7. Send out.

At this time, the line buffer 6 writes the data at the address designated by the counter 5 by the enable signal from the control unit 9 and the line buffer 7 at the address designated by the counter 8 by the enable signal from the control unit 9. When the line buffers 6 and 7 detect the line end, the control unit 9
Report to. The control unit 9 resets the counter 5 or 8 by this line end report and returns it to the initial value.

The length counter 3 counts the run length length from the data sent from the intermediate register 2 according to an instruction from the control unit 9, and reports to the control unit 9 when the counting is completed.

Based on this report, the control unit 9 resets the flip-flop 10, causes the decoder 1 to store the next decoded data in the intermediate register 2 as described above, and gives the length counter 3 a counting start instruction.

The intermediate register 2 sends the EOL sent by the decoder 1 to the decision circuit 12. The decision circuit 12 determines whether this EOL is added to the beginning of the message, or exists in the middle of the data and
It is determined whether the line data is divided or the telegram is terminated, and the result is reported to the control unit 9.

In the case of EOL added to the beginning of the message, the control unit 9 does not send the switching signal to the multiplexer 4, but sends the enable signal to the line buffer 6 if the line buffer 6 writes the data first.

If the EOL exists in the middle of the data, the switching signal is sent to the multiplexer 4 and the destination of the enable signal is also switched. For example, the enable signal sent to the line buffer 6 is switched to the line buffer 7.

If it indicates the end of the message, the multiplexer 4 is switched to the line buffer 6 side and the counters 5 and 8 are reset to the initial values.

[Problems to be solved by the invention]

As described above, conventionally, since the EOL added to the beginning of the electronic message is detected, a determination circuit is required, and the circuit configuration is complicated and economical, and the reliability is reduced.

[Means for solving problems]

The above-mentioned problem is that in a device that stores and processes one line of data transmitted by run-length code using a plurality of line buffers, address counting means for designating an address corresponding to each of the line buffers, And a detection means for detecting the count value of the address counting means at the time when the line termination code arrives, and if the count value of the address counting means is an initial value, it is determined to be the line termination code at the beginning of the message. Then, data is input to the line buffer, and if the address has a count value, it is determined to be a line termination code indicating a break in the data of one line of the electronic message, and the data of the line buffer is stored. The line buffer is switched without input.

[Action]

In other words, the counters that specify the addresses of the line buffers are all cleared to the initial value each time one telegram is completed, and one of the counters stores data in the line buffer during the telegram reception. It comes from the state of this counter by using having a count value other than the value
It detects the position of EOL in the telegram.

〔Example〕

FIG. 1 is a block diagram of a circuit showing an embodiment of the present invention.

The difference from FIG. 2 is that the control unit 9 can detect the count values of the counters 5 and 8 and the determination circuit 12 can be omitted.

That is, when the control unit 9 is notified of the EOL detection by the intermediate register 2, it checks the count values of the counters 5 and 8. If the count values of the counters 5 and 8 are both initial values, it is determined that the EOL is added at the beginning of the message. If either of them has the count value, it exists in the middle of the data and the Judge as indicating a break. If there are multiple EOLs, it is determined that the message has ended.

 The other operations are the same as those in FIG. 2 and their explanations are omitted.

〔The invention's effect〕

As described above, according to the present invention, from the state of the count value of the address counting means for designating the address of the line buffer, the EO
Since the changed position of L is detected, it is possible to perform efficient processing without requiring an extra processing configuration.

[Brief description of drawings]

FIG. 1 is a block diagram of a circuit showing an embodiment of the present invention, and FIG. 2 is a block diagram of a circuit for explaining a conventional line buffer switching system. In the figure, 1 is a decoder, 2 is an intermediate register, 3 is a length counter, 4 is a multiplexer, 5 and 8 are counters, 6 and 7 are line buffers, 9 is a control unit, 10 is a flip-flop, and 11 is an AN.
D circuit, 12 is a determination circuit.

Claims (1)

(57) [Claims] 1. An apparatus for storing and processing one line of data transmitted by a run length code using a plurality of line buffers, and address counting means for designating an address corresponding to each of the line buffers. And a detection means for detecting the count value of the address counting means at the time when the line termination code arrives, and if the count value of the address counting means is an initial value, it is determined to be the line termination code at the beginning of the message. Then, data is input to the line buffer, and if the address has a count value, it is determined to be a line termination code indicating a break in the data of one line of the electronic message, and the data of the line buffer is stored. A line buffer switching method characterized by switching the line buffer without inputting.