JPH03217943A - Data transmission error inspection code generation circuit - Google Patents

Abstract

PURPOSE:To simplify an arithmetic circuit by finding one of two value to be inserted to a protocol error inspection field from the value in which octet in protocol data unit is added, and the other from the value in which the value on one side is added. CONSTITUTION:An adder circuit 51 and a register 52 addition means to add data read out from a data storage part 1 in octet unit are provided at an arithmetic part 5, and a multiplier circuit 53, an input multiplexer 54, an adder circuit 55, a register 56, and a multiplier circuit 57 are provided at the arithmetic part 5 as means to find the value to be inserted from the output of the register 52 to one side of a protocol error inspection code field, and an adder circuit 31 and a multiplier circuit 32 are provided at an inspection information setting part 3 as the means to find the value to be inserted from the output of the multiplier circuit 57 and that of the register 52 to the other side of the protocol error inspection code field.

Description

[Detailed description of the invention] [Industrial application field] The present invention is used for transmitting digital data.

In particular, it relates to the generation of codes for detecting errors in information in protocol data units. More specifically, the present invention relates to a data transmission error check code generation circuit that obtains information to be inserted into a protocol error check field in a protocol data unit.

The present invention relates to the values to be inserted into two protocol error check fields in a protocol data unit; one value is determined from the sum of the octets in the protocol data unit, and the other is determined from the sum of the one value and the sum of the octets in the protocol data unit. This simplifies the circuit configuration.

[Conventional technology]

In order to detect data transmission errors, particularly protocol errors, a method of inserting an error check code into transmitted data has conventionally been used. In particular, the fourth layer of the OSI basic reference model,
In other words, in the transport layer, all data in the header and user data parts in the protocol data unit are processed based on the checksum algorithm, and based on the processing results, protocol error detection in the header part is performed. FIG. 3, which determines the information to be set in the code field, shows an example of the structure of a protocol data unit. This example shows a transport protocol data unit (hereinafter referred to as rTPDUJ) used in layer 4 of the OSI basic reference model.

The TPDU includes a header section and a user data section. The header section is provided with a length indicator Ll, a fixed length section, and a variable length section. The length indicator Ll is the first octet of the TPDU and indicates the length of the header section excluding itself. The fixed length part includes connection request [”R, connection confirmation CC,
It includes a TPDU code representing disconnection request DR, disconnection confirmation DC, data transfer DT, priority data transfer ED, data confirmation AK, priority data confirmation EA, or error notification 8R, and information regarding frequently used parameters. The length and structure of the fixed length portion is determined by the TPDU code. The variable length part is used to define parameters that are used less frequently. The data field is not involved in the transport layer and is used as the user data part.

In order to detect errors in the information in such protocol data units, a checksum parameter can be inserted in the variable length part. This parameter is used for connection request CR
It is present in all TPDUs except when the checksum option is not used.

FIG. 4 shows the format of parameters included in the variable length part. This format is common to each parameter, and in the case of a checksum parameter, r 1 is used as the parameter code.
1000011J is set, the parameter length is set to 2 octets, and the parameter value is set to the calculation result by the checksum algorithm.

FIG. 5 is a block diagram of a conventional data transmission error check code generation circuit.

The data storage unit 1 stores a protocol data unit including a protocol error check code field set to "O". In the case of a TPDU, the third and fourth octets of the checksum parameter correspond to the protocol error check code field.

The calculation unit 5 reads the protocol data unit from the data storage unit 1 in octet units from the beginning, performs addition processing, and holds the processing result.

The inspection information setting section 3 determines whether or not errors in the protocol data unit can be inspected based on the processing result of the calculation section 5,
The information is set in the corresponding protocol error check code field of the data storage unit 1.

The above operation will be explained in more detail.

In the calculation unit 5, a number indicating the octet position in the protocol data unit, L
is the octe-soto length of the protocol data unit, a. is the value of the octet in position 1.

Regarding parameter CO, adder circuit 51 and register 5
2. The parameter C1 is determined by the addition circuit 55 and the register 56.

The inspection information setting section 3 calculates the following. However, n is a number indicating the first octet position of the checksum number.

Regarding the value of X, the multiplier circuit 33 calculates the value of
O is multiplied by (L-n), the multiplier circuit 34 multiplies {parameter C1 by -1, and the adder circuit 35 adds the respective multiplied values. Further, regarding the value of Y, the multiplier circuit 36 applies the parameter CO-(L-
n+1) and adding the result and the parameter C1 in the adder circuit 37.

The check information setting unit 3 further inserts the determined values of X and Y into the first and second octets of the error check code field, respectively.

[Problem to be solved by the invention]

However, in the conventional data transmission error check code generation circuit,
At least four adder circuits and at least two multiplier circuits other than those for sign inversion are required.

An object of the present invention is to provide a data transmission error check code generation circuit that requires fewer arithmetic circuits.

[Indispensable means to solve problems]

The data transmission error check code generation circuit of the present invention includes an adding means for adding data in units of protocol data in units of octets, and means for determining a value to be inserted into one part of the protocol error check code field from the output of the adding means. , and means for determining a value to be inserted into the other part of the protocol error check code field from the output of the determining means and the output of the adding means.

[For production]

One of the two values to be inserted into the protocol error check field in the protocol data unit is determined from the sum of the octets in the protocol data unit. Moreover, the other value is found from the value added to the one value.

〔Example〕

FIG. 1 is a block diagram showing a data transmission error check code generation circuit according to an embodiment of the present invention.

This embodiment circuit includes a data storage section 1 that stores a protocol data unit including a protocol error check code field (first octet and second octet) that can be divided into two, and data stored in this data storage section 1. The check information setting unit 3 and the calculation unit serve as a processing means for reading and arithmetic processing in octet units, and setting error checkable information in the protocol error check code field stored in the data storage unit 1 based on the calculation result. 5.

Here, the feature of this embodiment is that the data storage section 1
The arithmetic unit 5 is equipped with an addition circuit 51 and a register 52 as an addition means for adding data read from the octet unit, and a value to be inserted into one part of the protocol error check code field is obtained from the output of the register 52. As a means, the arithmetic unit 5 is provided with a multiplication circuit 53, an input multiplexer 54, an addition circuit 55, a register 56, and a multiplication circuit 57, and the output of the multiplication circuit 57 and the output of the register 52 are inserted into the other of the protocol error check code fields. The test information setting section 3 is provided with an addition circuit 31 and a multiplication circuit 32 as means for determining the value.

The calculation unit 5 performs the calculation (hereinafter referred to as this page margin) on the protocol data unit data read from the data storage unit 1. Here, i, L, and ai are the number indicating the octet/soto position in the protocol data unit, the octet length of the protocol data unit, and the value of the octet at position i, respectively. Further, n is a number indicating the first octet of the checksum parameter.

Parameter CO is determined by addition circuit 51 and register 52 and stored in register 51. The input multiplexer 54 selects the value of the register 52 as is for the first (L-1) addition, and the value of the register 52 is selected by the multiplication circuit 53 for the final L-th addition.
-n-1> is selected and supplied to the adder circuit 55. By adding this in the adder circuit 55 and the register 56, the sign-inverted value of the value X to be set in the first octet of the error check code field is obtained in the register 56. The multiplication circuit 57 inverts the sign of the value stored in the register 56 and outputs it.

In the test information setting section 3, regarding the value Y to be set in the second octet of the error check field, Y = - (X + CO
). That is, the parameter CD stored in the register 52 and the output of the multiplication circuit 57 are added by the addition circuit 31, and the sign of this is inverted by the multiplication circuit 32. Furthermore, the test information setting section 3 sets two values X and Y in the first and second octets of the error check field, respectively.

FIG. 2 is a block diagram of a data transmission error check code generation circuit according to a second embodiment of the present invention. In this embodiment, the calculation unit 5
This embodiment differs from the first embodiment in that the value Y to be set in the second octet of the error check field is determined in step 1, and the value X to be set in the first octet in the check information setting section 3 is determined.

The calculation unit 5 performs the following calculations on the data in units of protocol data read from the data storage unit 1.

Parameter CO is determined by addition circuit 51 and register 52 and stored in register 51. The input multiplexer 54 selects the value of the register 52 as is for the first CL-1) addition, and the multiplication circuit 53 selects the value of the register 52 for the final L-th addition.
-n) is selected and supplied to the adder circuit 55. By adding this in the adder circuit 55 and the register 56, the value Y to be set in the second octet of the error check code field is obtained in the register 56.

In the test information setting section 3, regarding the value X to be set in the first octet of the error check field, X = - (Y + CO
). That is, the adder circuit 31 adds the parameter CO stored in the register 52 and the value Y stored in the register 56, and the multiplier circuit 32 inverts the sign. Further, the test information setting unit 3 sets two values XSY to the first and second octets of the error check field, respectively.

As explained above, both the first embodiment and the second embodiment,
Compared to the conventional example, the number of adder circuits and multiplier circuits can be reduced by one.

In the above embodiment, a configuration was explained in which multiplication by -1 is performed for sign inversion, but this operation is based on one's complement representation, and even if the multiplication circuit is removed as a configuration for extracting sign-inverted data from a register, the present invention will not work. The invention can be practiced similarly.

In the above description, the TPDU was used as an example of a protocol data unit, but the present invention can be similarly implemented in the case of a checksum for other protocol data units, for example, a third layer (network layer) protocol data unit.

〔Effect of the invention〕

As described above, the data transmission error check code generation circuit of the present invention has the effect of simplifying the circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a data transmission error check code generation circuit according to a first embodiment of the present invention. FIG. 2 is a block diagram of a data transmission error check code generation circuit according to a second embodiment of the present invention. FIG. 3 is a diagram showing an example of the structure of a protocol data unit. FIG. 4 is a diagram showing the format of parameters included in the variable length part. FIG. 5 is a block diagram of a conventional data transmission error check code generation circuit. 1... Data storage section, 3... Examination information setting section, 5.
... Arithmetic unit, 31, 35, 37, 51, 55... Addition circuit, 52, 56... Register, 32, 33, 34,
36, 53, 57...Multiplication circuit, 54...Manual multiplexer.

Claims (1)

[Claims] 1. A data storage unit (1) that stores a protocol data unit including a protocol error check code field that can be divided into two parts; and a data storage unit (1) that reads data stored in this data storage unit in units of octets. processing means (3,
5) In the data transmission error check code generation circuit, the processing means includes: adding means (51, 52) for adding data read from the data storage section in units of octets; and an output of the adding means. means (53 to 57) for obtaining a value to be inserted into one part of the protocol error check code field from the above; and a value to be inserted into the other part of the protocol error check code field from the output of this calculating means and the output of the adding means; and means (31, 32) for determining a data transmission error check code.