JPS61148556A - Control code detector of communication - Google Patents

Abstract

PURPOSE:To make high-speed retrieval possible by referring to a table and performing the logical operation using elements in this table to convert characters to information which discriminates whether characters are a control code or not. CONSTITUTION:A retrieval table 4 of elements is provided in a communication controller, and elements in this table are so constituted that valid bits related to the first character of a control character code and valid bits 6 related to the second character are adjacent. In case that a control code is retrieved from a character string 1, an element 9 corresponding to a character 2 to be retrieved is extracted from the table, and an element 10 obtained by retrieving the control code with respect to a character 3 preceding the character 2 is preserved in a storage, and AND among data obtained by shifting this element 10 by one bit, the element 9, and a mask 7 where bits other than valid bits are ''0'' at the retrieval time is operated to generate a discriminator 8 which discriminates whether the character 2 or the combination of the character 2 and the preceding character 3 is the control code or not. The character string is transferred to the control code detection processing in accordance with content of this discriminator. Thus, retrieval is performed in a high speed with a minimum quantity of hardware.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to digital communication control, and in particular, the present invention relates to digital communication control, and in particular, to a process in which a specific process is requested from the outside to the processing fe pupil from among a character string input from the outside. The present invention relates to a communication control device capable of detecting a control character code meaning .

[Background of the invention]

First, the system configuration is shown in FIG. 6.

The communication system # device 14 is located between the processing device 11 and the external device 15, and controls data transfer between the external device and the processing device using a built-in microprocessor according to commands issued from the processing device. The communication control device is Cubo Denki's "non-procedure upper link unit" 3G2A2.
- It is possible to detect a start character and an end character from a received character string, such as LKOO5. The start character and end character differ depending on the external device connected. Some have one character, some have two characters, and some have many different characters with the same meaning. In order to increase the versatility of the communication control device, the following two characters are recommended. It is necessary to satisfy two conditions.

Hatake: Control characters such as the text start character code, end character code, attention interrupt character code, and X0N10F'F character code used for waiting control between the communication device and the external device from among the character strings input from the external device. The code must be detectable.

(2) Regarding control character codes, both the character structure and the number of characters other than the XoNloFF character code vary depending on the specifications of the external device to be connected, so these should be able to be set according to the external device.

Furthermore, even if the specifications of the control code are complex, it is necessary to perform processing at high speed without reducing the processing speed to ensure high throughput. Below is the string or bw
A conventional example of a method for searching for specific characters will be explained.

One way to search for a specific character in a string is to compare it with the character to be searched for, starting from the first character in the string. If the character to be searched is a single character, this method only requires one 8-bit comparison for each character in the string, but if there are two characters, a 10-bit comparison or an 8-bit comparison is performed for each character in the string. Bit comparison must be performed twice.Furthermore, if there is more than one type of character to be searched, that is, if there are multiple S classes, if the character to be searched is one character, n-time 8-bit comparisons are required; if two characters are to be searched, n times Ban
Either 2n child bit comparisons or 2n 8-pit comparisons must be performed. This increases the processing time required to search for characters and reduces throughput, which becomes an obstacle to increasing the data transmission speed with the outside.

Here, if there are many different characters to search for, the search method is as follows:
VAXIIARCITECTURE HANDBOO
Like the processing method for the '5CANC' instruction explained in ``K'', before the search, a table consisting of 256 elements is created, each element has a valid bit, and Matamurasaki is performed. Valid bit f of the element corresponding to the character
: Set to ``1'', set the valid bits of other elements to 0'', and mask in the string (only when the valid bit is @I 11 after logical AND with the element,
There is a method of determining whether or not the character is the character to be searched based on the result of logical multiplication with a non-zero numerical value. With this method, even if there are multiple characters to be searched, the valid bits of the elements corresponding to all the characters to be searched in the table are
1", and the time required for the search process will not increase even if the number of types increases. Moreover, if the post-detection processing differs depending on the detected character, in other words, Roru characters will be ignored in the text that follows. If the starting character is the starting character of the text, and other characters are ending with the ending character of the text, the processing of the communication control device and the processing device after detection will be different, but in such a case, each element in the table should have multiple characters. By providing a valid bit corresponding to the start character and a valid bit corresponding to the end character, it is easy to limit the branch judgment of processing after detection to one character.
When performing two-character calculation, the number of elements in the table must be set to two characters, that is, 256" = 65536, which results in a significant /... It is not suitable for detecting characters consisting of one or two characters.

[Object of the Invention] An object of the present invention is to provide a communication control device that can search for a wide variety of one-character or two-character control character codes at the same speed and with a minimum amount of hardware. .

[Summary of the invention]

As shown in FIG. 5, the present invention provides a search table 4 of 256 elements inside the communication system-I@l device, and the configuration of the elements of this table is set to valid bit 5 for the first character of the control character code and valid bit 5 for the second character of the control character code. When searching for a control code from character example 1 with valid bits 6 adjacent to each other, extract element 9 corresponding to searched sentence F2 from the table, and search for a control code for character 3 before the - character. The element 10 obtained when performing the above is stored in memory, shifted by one pit, and the element 9 is ANDed with the mask 7 that sets all pits other than those valid at the time of search to 0''. 9 Discriminator 8 for determining whether character 2 or the combination of character 2 and character 3 before it is a control code.
This method is characterized in that it creates a discriminator and transitions to control code detection processing based on the contents of this discriminator. In this case, the content of discriminator 8 is if character 9 is the second character of the control code.
It is the AND of valid bit V, which is IIT, and valid bit V1, which is 1'' when the character 10 before the character is the first character of the control code, and is the combination of the character and the character before it. It becomes '1' only when corresponds to a control code.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows the internal configuration of the communication control device.

'The communication control device waits for the microprocessor 17 and memory 18 on the internal bus 19, and performs input/output with the processing device and external equipment through the system bus interface 16 and external devices, respectively. The configuration allows for Data input/output between the processing unit and external devices is controlled by a microprocessor, and data from external devices can be stored in memory.
Responsiveness to input can be ensured even when high-speed input/output is performed.

FIG. 2 shows the internal configuration of the memory 18. Search table 4 is composed of 256 elements, the first element corresponds to the character code (00)16, and the next element corresponds to the character code (01).
)16, the last element corresponds to character code (FF)16. The element storage area 10 is an area for storing the element corresponding to the previously input character. FIG. 3 shows the format of each element of the search table 4 and the element storage area 10. FIG. 4 shows the control flow of the microprocessor 17 for inputting one character. The element corresponding to the input character and the element corresponding to the character input before it (
Then, in order to extract the valid pits of this logical product, a logical product is performed with the mask pattern. If the result of this operation is O, it can be determined that the character is not a control character code, and if it is not 0, it can be determined that it is a control character code.

If the control character code is one character, set the meaning pit, which is the first character of that kind of control character code, to 1'' for all elements, and then set that kind of control character for the element corresponding to the control character code. Set the second character of the code, the meaning pit, to #1''. This allows you to search for control character codes in the same way as for two-character codes,
If so, the same program can perform a search even if the number of characters in the control character code is different, such as an attention character being one character and a starting character being two characters. FIG. 4 shows an algorithm for simultaneously searching for a start character and an attention character when data is manually input. In this algorithm, the XoNloFF character is simultaneously searched by referring to the search table once, and four types of control codes are simultaneously searched using a simple algorithm. The size of the table is at most 2
It only takes 56 bytes, and even if the processing is performed using an inexpensive Hebit microprocessor, the search can be performed in about 10 steps during the day, and the processing speed is sufficiently high for practical use.

Note that 12 is a main storage device, 13 is a system bus, 15 is an external device, and 21 is a valid bit.

〔Effect of the invention〕

According to the present invention, by converting a search for a two-character control character code into information sufficient to determine whether or not it is a control code by referring to a table and performing a simple logical operation using the elements of the table. , can be performed at high speed, and can be easily processed by an inexpensive Hebit microprocessor.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the internal configuration of a memory according to an embodiment of the present invention, Fig. 2 is an internal configuration diagram of a communication control device, Fig. 3 is a layout diagram of valid bits of a search cable taken up in the implementation column, and Fig. 4 is a diagram of an internal configuration of a communication control device. The figure is a flowchart showing the process flow of the embodiment, FIG. 5 is a diagram showing the process flow, and FIG. 6 is a communication control device, a processing device,
and a connection diagram showing mutual relationships between external devices. 1...Character string input from outside, 4...Search table, 9...Example of elements in the table, 14...
Communication system 1st line to external device 3rd line VxoN VvorF VY2 VTI
Vs2 VSI V12
VAI broom 4-Figure 5 [21

Claims (1)

[Claims] 1. Consists of a system bus interface connected to the system bus of the processing device, an external interface connected to external equipment, a memory, and a microprocessor that controls them and controls data input/output between the external equipment and the processing device. In a communication control device between an external device and a processing device, a search table whose constituent elements are data in which the valid bit, which is the first character of the control code, and the valid bit, which is the second character, are shifted by n bits. It has an element storage area in memory for storing the element of the search table corresponding to the character that has undergone output processing, and the character that has undergone input/output processing one character before is stored in the element storage area. The corresponding element is shifted by n bits to indicate that the element corresponding to the character currently being input/output is the first character of the control code, and the element corresponding to the previous character is the first character of the control code. To perform a logical AND operation between the bit position of the valid bit indicating that it is two characters and the element corresponding to the character currently being input/output, and eliminate the invalid bit from the operation result. , further characterized in that the two-character control code is detected at high speed from the character string input from the external device by performing a logical product with the mask pattern and determining whether the result of this operation is 0 or not. shall be. Control code detection device for communication control equipment.