JPS6162274A - Adaptable buffer memory controller - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an underflow in buffer memory by issuing a transmission request signal from an encoding part when one side of the buffer memory is full, and transferring and controlling data stored in the buffer memory side to an output control part with the transmission request signal and a reception request signal from an output control part. CONSTITUTION:A facsimile image signal which id displayed in black/white binary values and inputted from an input terminal 1 is converted by an encoding part 2 to write it in one of plural built-in buffer memories. When said memory is full or conversion data of input signals of the prescribed number of lines are accumulated, the transmission of data is demanded to a control part 4, and simultaneously said buffer memory is switched to another memory to continue writing of the conversion data. On the other hand, an output control part 3 incorporates two buffer memories, reads out the data written in one memory at a constant speed and outputs it to a facsimile device from an output terminal 5. When the data in said memory becomes empty, the output control part 3 requests the control part 4 to receive the data and simultaneously said buffer memory is switched to the other to read and transmit data.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical field to which the invention pertains The present invention relates to a data transfer device or the like that converts an input signal into a variable length signal and outputs the signal to a terminal device via a transmission line. The present invention relates to an adaptive buffer memory controller used for matching.

Conventional technology Conventionally, this heel data transfer device is equipped with a plurality of fixed-capacity buffer memories, and sequentially writes converted data obtained by converting an input signal into variable-length data to one buffer surface, until the buffer surface becomes full. When this happens, the speeds of input and output data are matched by switching to another buffer surface and applying the converted data, and at the same time controlling to send out the data from the full buffer surface. The capacity of the eight buffer planes is determined to be the optimum value by considering the average amount of converted data input to the buffer and the transfer rate of output data. However, the above-mentioned control method has a drawback that, as described below, underflow of the buffer memory occurs when the amount of generated conversion data corresponding to input data is uneven.

For example, when inputting a facsimile signal and performing code compression using the modified Huffman encoding method, the facsimile image signal expressed in black and white binary is encoded in units of scanning lines in the encoding section. For example, if the number of pixels for each line is 1728 bits, the encoded output data after conversion will range from a minimum of 28 bits (when all image signals of one scanning line are white) to a maximum of 172 bits.
It may be 8 bits or more. In other words, the number of bits of the encoded output (converted data) varies greatly depending on the state of the input image signal.

In facsimile communications, about half of the message is often blank, and when this is encoded, the code of the minimum bit (29 bits) is output as **. Therefore, the amount of converted data generated is extremely small compared to human data, and the amount of converted data per line is biased to be much lower than the average value. On the other hand, since the encoding processing time is almost constant for each line, it takes a long time to fill one side of the buffer memory with conversion data, and the data from the backup memory side that is full first is read out. By the time the sending is completed, the next buffer memory surface is not yet full of data. In the conventional buffer memory control method, the data is not transferred to the output aj control unit until one buffer surface is full, so in the above case, (±.../<777)%1')77° When - occurs? , has the disadvantage of dying.

OBJECTS OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, and to perform control such that when the amount of converted data generated by the encoder is small, it is transferred to the output controller even if the buffer memory is not full. Another object of the present invention is to provide an adaptive backup memory control device that prevents underflow of a buffer memory even when the amount of data generated is uneven.

Structure of the Invention The adaptive backup memory control device of the present invention includes an encoding section that converts an input signal into variable length data and sequentially writes it into 'Igi number of backup memories, and a plurality of buffers for storing the output data of the encoding section. A buffer memory control device comprising: an output control section that sequentially stores data in a memory and outputs the stored data to a terminal device; and a control section that controls data transfer between the output control section and the encoding section. The section outputs a transmission request signal when one side of the backup memory becomes full or when converted data corresponding to a predetermined amount of input signals is accumulated, and the control section outputs a transmission request signal from the transmission request signal and the output control section. The data stored in the buffer memory surface is controlled to be transferred to the output control section by the reception request signal.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

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

That is, a facsimile image signal expressed as a black and white z value inputted from the input terminal l is converted into a modified Huffman code by the encoder 2, and written into one side of a plurality of built-in buffer memories, and one side is When it is full or when conversion data of input signals for a predetermined number of lines has been accumulated,
At the same time as requesting the control unit 4 to send data, the buffer memory side is switched to another side and converted data is continuously written. Note that the capacity of the above buffer memory 1 side is equal to the converted data of the encoding unit 2. It is determined to be optimal in consideration of the amount of generation and the amount of data sent from the output control unit 3 to the terminal device.

On the other hand, the output control unit 3 has two built-in backup memories,
The data written on one side is read out at a constant speed and output from the output terminal 5 to the facsimile terminal, and when the data on the first side becomes empty, a request is made to the control unit 4 to receive the data, and at the same time, the backup memory is transferred to another The data is read out and sent out. However, for data transmission from the output control unit 3 to the terminal device, a minimum transmission time (about 20!l!+) per line is specified (even if the number of bits is small). When the control unit 4 receives both a transmission request from the encoding unit 2 and a reception request from the output control unit 3, the control unit 4 controls the transfer from the backup memory of the encoding unit 2 to the buffer memory of the output control unit 3. to start.

In order to make a transmission request from the encoder 2, it is necessary that one side of the backup memory be full or that converted data for a predetermined number of lines be stored. The predetermined number of lines is within the minimum time for the output control unit 3 to finish sending the modified Huffman encoded data written on one side of the backup memory (for example, 8 bytes) to the terminal device (for example, 8 bytes 9800b/ 6.8 seconds when transmitting in s), and the number of lines that can be converted by the encoder 2 (for example, all white (conversion processing time per line is 17 m5) is 400.
Therefore, for a line containing one character, etc., one side of the buffer memory becomes full with conversion data of 400 lines or less (for example, 200 lines), and a transmission request is made at that point. If there are many white lines, and 400 lines of converted data are stored on one side of the buffer memory, a transmission request will be issued even if the buffer memory is not full.

In this embodiment, if the amount of converted data per line of the encoded output of encoded part 2 is small, the output can be output even if one side of the buffer memory is not full (for example, 400 lines of all white). Since it is possible to transfer the information to the control unit 3,
Even if the amount of data generated is uneven, buffer memory underflow t''% I:''t'z' kL゛5
9Jt'i! :i<h6・.

FIG. 2 is a block diagram showing another embodiment of the present invention.
■Figure 1. In this case, a facsimile message represented by characters, symbol codes, etc. is input from the input terminal 1. Then, in the code conversion unit 6, the received code signal is once converted into a slam image signal represented by black and white z-value dots. It is converted into an image signal and sequentially stored in a plurality of built-in buffer memories.Then, as in the previous embodiment, one side of the buffer memory becomes full or a certain line a (for example, 400 lines) is reached.
When the converted data for the number of minutes is stored, a transmission request signal is sent to the control unit 4.

On the other hand, the terminal-control unit 7 has a built-in buffer memory on two sides, reads data written on one side, and sends the data from the output terminal 5 to the facsimile terminal at a constant transmission rate (for example, 9800
b/g), and when the data on the first side becomes empty, it requests the control section 4 to receive the data, and at the same time switches the buffer memory to another side to read out and send out the data. However, for data transmission from the terminal control unit 7 to the terminal device, 1
It requires a time longer than the minimum transmission time (about 20 as) per line. When the control unit 4 receives both the transmission request from the code pattern conversion unit 6 and the reception request from the terminal control unit 7, the control unit 4 transfers data from the backup memory of the code pattern conversion unit 6 to the buffer memory of the terminal control unit 7. Start the transfer.

Therefore, in this case as well, even if one side of the buffer memory of the code pattern conversion section 6 is not full, it is possible to transfer the data to the terminal control section 7, and underflow does not occur. .

In the present invention, the format of the signal input from the input terminal 1 is not limited to the aforementioned facsimile signal, character code signal, etc., and the converted data output from the output terminal 5 is modified Huffman code. In short, the present invention is not limited to conversion signals, and can be applied to all transfer devices that convert and output data of variable length according to an input signal. In that case, when converted data corresponding to a predetermined amount of input signal is stored in the buffer memory, it may be possible to transfer it even if the buffer memory is not full. It can be set appropriately taking into consideration.

Effect of +411 As described above, in the present invention, when the amount of converted data generated by the encoding section is small, when the converted data corresponding to a certain amount of input signal is &Ued to the backup memory,
Output Fr1 even if one side of the buffer memory is not full
Since the structure is configured so that data can be transferred to the J control section, there is an effect that underflow of the buffer memory does not occur even if the amount of data generated by the encoding section is uneven.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing another embodiment of the invention. In the figure, 1: input terminal, 2: encoding section, 3: output control section, 4: control section, 5: output terminal, 6: code pattern conversion section, 7: terminal control section.

Claims (2)

[Claims] (1) An encoding unit that converts an input signal into variable length data and sequentially writes it into multiple buffer memories, and stores the output data of the encoding unit sequentially in multiple buffer memories and outputs the stored data to a terminal device. In the buffer memory control device, the encoding unit includes an output control unit that controls data transfer between the output control unit and the encoding unit, and a control unit that controls data transfer between the output control unit and the encoding unit. or when converted data corresponding to a predetermined amount of input signals has been accumulated, a transmission request signal is output, and the control section uses the transmission request signal and the reception request signal from the output control section to transfer data to the buffer memory surface. An adaptive buffer memory control device, characterized in that it controls the transfer of stored data to the output control section. (2) In the adaptive buffer memory control device according to claim 1, the encoding section includes a code pattern converting section that encodes a facsimile message expressed by a character code or the like into modified Huffman encoding. , wherein the output control section is comprised of a terminal control section that transmits the modified Huffman encoded facsimile signal to the terminal facsimile device at a constant speed.