JPH0477989B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data record compression method, and particularly to data record compression in which a plurality of compressed records obtained by compressing one record are combined into one new record. Regarding the method.

[Conventional technology]

When recording a record consisting of a single logical record or a plurality of blocked logical records on a magnetic tape device, for example, as shown in FIG. 6a, such a record L
1 to L4 themselves, there is a limit to the number of records that can be recorded per unit length. In addition,
In the figure, IRG is the gap between records.

Therefore, in the past, the following compression methods have been used to improve the usage efficiency of recording media.

If the record to be recorded is, for example, the data pattern AAAABCDDEFFF (each represented by 8 bits) as shown in FIG.
(This number is called a compression threshold) For example, in the case of three or more, compression is performed by setting the 0th compression identification bit to "1" and setting the number of repetitions of the compressed data in the 1st to 7th bits as shown in Figure 6c. An identification code is added immediately before the repeated data, and if three or more pieces of the same data are not consecutive, the 0th bit compression identification code is set to "0" as shown in Figure 6d, and the 1st to 3rd bits are A compression identification code in which the number of non-consecutive identical data sets (the number of uncompressed data) is set in 7 bits is added immediately before the data that does not contain continuous identical data. Figure 6e shows the contents of a compressed record obtained by compressing the record shown in Figure 6b using the above method, and since there are four consecutive pieces of data A, the compression identification code has the value (84) ₁₆ in hexadecimal notation. is added immediately before data A, and then there are 5 characters of BCDDE that do not contain consecutive identical data, so a compression identification code with a value of (05) ₁₆ in hexadecimal is placed immediately before those characters, and then Since there are three consecutive F characters, a compression identification code (83) ₁₆ to that effect is placed immediately before the F character. The number of bytes of the record shown in FIG. 6b is 12, while the number of bytes of the compressed record shown in FIG. 6e is 10, indicating that the record can be compressed. Of course, the effect of such compression increases as the number of consecutive pieces of the same data increases.

Now, in the conventional data record compression method, the records L1 to L4 shown in FIG. 6a are compressed as described above.
Each of the compressed records CL1 to CL4 obtained by compressing the data is notified to a recording control device such as a magnetic tape controller, and is recorded on the magnetic tape as a new record as shown in FIG.

[Problem that the invention seeks to solve]

However, even in the conventional method, the usage efficiency of the recording medium is still insufficient. That is the 6th
This is because, as shown in FIG. f, there is an inter-record gap IRG in every compressed record.

The present invention solves these conventional drawbacks, and aims to provide a system that can further improve the efficiency of use of recording media.

[Means for solving problems]

In order to achieve the above object, the present invention includes: a data compression means that performs compression processing on a record-by-record basis to generate a compressed record; a counting means that counts the record number of the record currently being processed; undefined data compression code generation means for generating a predetermined number of first undefined data compression codes and a second undefined data compression code according to the count value of the counting means; a data buffer for storing compressed records and first and second undefined data compression codes generated by the undefined data compression code generation means; A predetermined number of first compressed records generated by the undefined data compression code generating means are stored in the data buffer at the address next to the storage address.
and a number of second undefined data compression codes corresponding to the count value are executed for a plurality of records until a predetermined amount or more of data is stored in the data buffer. , means for converting the contents stored in the data buffer at the time when the predetermined amount or more of data is stored into one new record.

[Effect]

One new record of the contents stored in the data buffer includes multiple compressed records,
Unlike the conventional method, it is not possible to separate compressed records by non-data areas such as gaps between records, but since an undefined data compression code is added after each compressed record, this Compressed records can be divided into sections, and by including a plurality of compressed records in one record, non-data areas such as gaps between records can be reduced, and the usage efficiency of the recording medium can be improved.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. When the recording control device 8 receives a record to be recorded from a record sending source (not shown), it sends it to the data record compression mechanism CP, which will be described later. When the data record compression mechanism receives notification from the data record compression mechanism CP of the generation of one new record and the completion of storage, the data record compression mechanism
The new record is taken out from the CP and recorded on the magnetic tape of the magnetic tape device 9.

In this embodiment, the data record compression mechanism CP includes a data compression section 1, a record data end determination section 2, an undefined data compression code generation section 3, a data buffer control section 4, and a record number counting section 5.
, a data buffer 6, and a data selector 7.

When data constituting a record is input from the recording control device 8 via the data line 21, the data compression unit 1 starts compression processing similar to the conventional compression method explained in FIGS. When the data compression operation end instruction signal 12 is input from the data end determination unit 2, the compression process is terminated, and the data compression operation end signal 16 is sent to the record data end determination unit 2, and at the same time, one record generated at that time is A compressed record of 1 is outputted to the compressed data line 22, and a signal 30 is set to "1" to notify the data buffer control section 4 each time it is output.

When the record data end determination section 2 receives a data end signal 11 from the recording control device 8 indicating that all data of one record has been sent out via the data line 21, the record data end determination section 2 instructs the data compression section 1 to end the data compression operation. When the instruction signal 12 is sent and the data compression operation end signal 16 is received from the data compression section 1, the data compression record end signal 13 is sent to the undefined data compression code generation section 3, the record number counting section 5, the data selector 7 and the data buffer control. Send to section 4.

The record number control unit 5 internally counts up by the data compression record end signal 13,
It has a counter that is cleared by a signal 33 from the data buffer control section 4, and information on the record number currently being processed is sent to the undefined data compression code generation section 3 and the data buffer control via a signal line 35. Notify Department 4.

When the undefined data compression code generation unit 3 receives the data compression record end signal 13, it generates a predetermined number of first undefined data pieces (the number may be one or more, but preferably the number is equal to the compression threshold). A compression code (a code that exists in the data but does not exist as a data compression code, such as (80) ₁₆ in hexadecimal notation in the compression methods of examples 5b to 5e) is output to the record identification data line 23. , and notifies the data buffer control section 4 by setting the signal 31 to "1" each time the data is output. Subsequently, a second undefined data compression code (for example, a code other than (80) ₁₆ , for example (00) _16, etc.) is applied to the record identification data line in a number corresponding to the number notified from the record number counting section 5. 23, and also notifies the data buffer control unit 4 by setting the signal 31 to "1" each time it is output.

The data selector 7 selects a data compressed record end signal 13 from among the compressed record added via the compressed data line 22 and the undefined data compressed code added via the record identification data line 23.
and one determined by the state of the signal 37 from the data buffer control section 4, and outputs it to the data buffer 6 via the record compression data line 24.

The data buffer 6 stores an amount of data commensurate with the maximum capacity that the recording control device 8 can process once or multiple times (for example, in the case of magnetic tape, the data length that can be stored in the maximum tape length that can be written continuously). It's a good deal to get.

The data buffer control unit 4 controls the data buffer 6
The data compression unit 1 controls writing and monitors the amount of data stored in the data buffer 6.
Alternatively, when the signal 30 or 31 from the undefined data compression code generation section 3 becomes "1", the internal write address counter is updated and the write address is sent to the data buffer 6 via the data buffer address line 25. along with the light signal 32
Send out. Furthermore, when such writing is performed sequentially and the amount of data stored in the data buffer 6 exceeds a predetermined amount, a data amount over signal 14 is output to the recording control device 8, and after this, the last undefined data compression code is output. When the data is stored in the data buffer 6, this is notified to the recording control device 8 by a signal 33, and the final storage address is notified to the recording control device 8 via the final address notification line 34. Here, the predetermined amount monitored by the data buffer control section 4 is such that when the data amount over signal 14 is notified and the recording control device 8 stops sending out a new record, the storage capacity of the data buffer 6 reaches its maximum capacity. The capacity is set to be as close to the maximum capacity as possible without exceeding it.

When the recording control device 8 receives the data amount over signal 14 from the data buffer control section 4, it stops sending out the next record, and one new record is added to the data buffer 6 by the signal 33 from the data buffer control section 4. When it is detected that the data has been stored, the data from the start address of the data buffer 6 to the address notified by the final address notification line 34 is transferred to one data buffer 6 by giving a control signal 36 including a read address, a read signal, etc. It is read out as a new record and recorded on the magnetic tape of the magnetic tape device 9.
Then, the process moves to compression processing and recording processing for another record.

FIG. 2 is a block diagram of an embodiment of the data buffer control unit 4, which includes an OR circuit 40 that takes the logical sum of the signals 30 and 31, and a write circuit that generates the write signal 32 for the data buffer 6 based on the output of the OR circuit 40. A signal generation circuit 41, a counter 42 which is incremented by the output of the OR circuit 40 and generates a write address for the data buffer 6, a register 43 which stores a predetermined address value, and a counter 42.
a comparator 44 that compares the output value of the counter 2 with the set value of the register 43 and sets the output to "1" when the output value of the counter 42 exceeds the set value of the register 43;
An adder 48 adds the record number output from the record number counting unit 5 to the record number data line 35 and the number of additions of the first undefined data compression code, for example "3", and the output of this adder 48 is used as data. It is preset at the timing of the record compression operation end signal 13, and is counted down each time the signal 31 becomes "1". When the content reaches "0", the output is set to "1", and when cleared, the signal 31 becomes "1". A counter 45 and a comparator 44
The register 47 comprises an AND circuit 46 which performs a logical product between the output of the AND circuit 46 and the output of the counter 45, and a register 47 which latches the value of the counter 42 using the output of the AND circuit 46 as a latch timing. The output of the comparator 44 becomes the data amount over signal 14 and is sent to the recording control device 8, and the output of the AND circuit 46 becomes the record storage end signal 33 and is sent to the register 4.
The contents of 7 are respectively sent to the recording control device 8 as the final storage address, and the output of the counter 45 is input as a signal 37 to the data selector 7.
Note that the counter 42 is cleared to the initial value "0" by the output of the AND circuit 46.

FIG. 3 is a block diagram of an embodiment of the undefined data compression code generator 3, which includes a register 50 for storing the first undefined data compression code (80) ₁₆ , and a second undefined data compression code (00). ) ₁₆ , a selector 52 that selects the first and second undefined data compression codes, and an oscillator 53 that generates pulses at a predetermined period when activated by the data compression record end signal 13. , an AND circuit 54 with the output of the oscillator 53 as one input and the output of the selector 52 as the other input, a counter 55 counted up by the output pulse of the oscillator 53, and a count value of the counter 55 and a first undefined Number of data compression codes added (“3” in this case)
a comparator 56 which compares the values of the counter 55 and sets its output to "1" when the value of the counter 55 exceeds a constant "3"; an AND circuit 57 which receives the output of the comparator 56 and the output of the oscillator 53; A counter 58 is incremented by the output of the circuit 57, and a register 5 is set to the contents of the record number data line 35 at the timing of the data compression record end signal 13.
9, and a comparator 60 which compares the value of this register 59 and the count value of a counter 58 and sets its output to "1" when the value of the counter 58 exceeds the value of the register 59. AND circuit 5
4 is sent to the register identification line 23, and the output pulse of the oscillator 43 becomes the signal 31. Further, since the output of the comparator 60 becomes "1", the operation of the oscillator 53 is stopped and the counters 55 and 58 are cleared to "0". Further, the selector 52 selects the register 50 side when the output of the comparator 56 is "0", and selects the register 51 side when the output is "1".

For convenience of explanation, the capacity of the data buffer 6 is, for example, from the 1st address to the 48th address as shown in FIG.
The total number up to the address is 48 bytes, and "34" is set in the register 43 of the data buffer control unit 4.
Further, assuming that all the records sent from the recording control device 8 to the data compression unit 1 have the same contents as shown in FIG. 6b, the operation in FIG. 1 will be as follows.

When the data constituting one record shown in FIG. Therefore, the data of (84) ₁₆ is applied to the data selector 7 via the compressed data line 22, and the signal 30 is set to "1" for a predetermined time. At this time, the data compression record end signal 13 has become "0" and the data selector 7 has selected the compressed data line 22 side, so the data (84) ₁₆ is input to the data buffer 6. Further, the initial value of the counter 42 of the data buffer control unit 4 is "0",
The signal 30 applied via the OR circuit 40 is “1”
The address with the content of "1" is added to the data buffer 6 via the data buffer address line 25, and the write signal 32 is sent from the write signal generation circuit 41 to the data buffer 6.
sent to. Therefore, the data (84) ₁₆ is stored at the first address of the data buffer 6 as shown in FIG.

Next, the data compression means 1 outputs the data A to the compressed data line 22 as shown in FIG. 6e, and sets the signal 30 to "1", and thereafter, as shown in FIG. ₁₆ , B, C, D, D, E, (83) ₁₆ ,
The data is sent out in the order of F and the same operation as described above is performed, so that the data is sequentially stored in the second address to the tenth address of the data buffer 6.

When the recording control device 8 finishes sending out the last data of one record (F in this case), it sends a data end signal 11 to the record data end determination section 2, and in response, the record data end determination section 2
sends a data compression operation end instruction signal 12 to the data compression section 1. The data compression unit 1 thereby completes the current compression process, and notifies the record data end determination unit 2 of this fact using a signal 16.

When the record data end determination section 2 receives the above notification, it sends out a data compression record end signal 13, switches the data selector 7 to the undefined data compression code generation section 3 side, and activates it.

When the undefined data compression code generation unit 3 is activated, it takes in the output “1” of the register number counting unit 5 at that time into the register 59, and the oscillator 53 starts operating and generates the first pulse. (The register number counting unit 5 then counts up the internal counter and sets it to "2"). At this time, since the selector 52 is set to the register 50 side, the first undefined data compression code (80) ₁₆ stored in the selector 52 is set to the AND circuit 54,
It is sent to the data buffer 6 via the record identification data line 23 and the data selector 7, and the signal 31 becomes "1" for a predetermined period of time. At this time, the counter 55 is counted up from "0" to "1".

When the signal 31 becomes "1", the counter 42 of the data buffer control section 4 counts up to "11", and the write signal generating circuit 41 generates a write signal 32. Therefore, the first undefined data compressed code (80) ₁₆ sent from the undefined data compressed code generator 3 is sent to the data buffer 6 as shown in FIG.
It will be stored at the 11th address of

The undefined data compressed code generating section 3 repeats the above operation unless it has sent out a predetermined number of undefined compressed codes. That is, in this embodiment, three undefined compressed codes are consecutively sent, and the output of the comparator 56 remains "0" even after the first and second undefined data compressed codes are sent. Since the selector 52 remains set to the register 50 side, when the second and third pulses are output from the oscillator 53, the selector 52 outputs the second and third first signals. Definition data compression code (80) ₁₆ is sent to the register identification data line 23 via the AND circuit 54. Therefore, the 12th and 13th addresses of the data buffer 6 are
(80) ₁₆ is stored in the address.

Then, by sending the third first undefined data compression code, the output of the comparator 56 becomes "1", and the selector 52 is switched to the register 51 side. Therefore, when the fourth pulse is output from the oscillator 53, the second undefined data compression code (00) ₁₆ stored in the register 51 is transferred to the data buffer via the selector 52, the AND circuit 54, and the register identification data line 23. The second undefined data compression code (00) ₁₆ is stored in the fourteenth address of the data buffer 6 by the same operation as described above. At this time, the counter 58 is connected to the AND circuit 57.
Since it is open, it is counted up and becomes "1", and the current stored value of register 59 is "1".
, the output of the comparator 60 becomes "1", the oscillator 53 stops operating, and the counter 5
5 and 58 are cleared to "0".

On the other hand, the recording control device 8, while transmitting the record,
It detects whether the data amount over signal 14 has been sent from the data buffer control unit 4,
If not, the next record is sent to the data compression unit 1 following the previous record. In this embodiment, since "34" is set in the register 43 of the data buffer control section 4, the recording control device 8 sends out the second and third records. That is, at the time when data C is stored in the 34th address of the data buffer 6, that is, while the third record is being sent, the output of the comparator 44, that is, the data amount over signal 14 becomes "1", so that the recording control device 8 will stop sending out the fourth record. Then, at the address after the second compressed record, the first undefined data compression code (80) ₁₆ is changed to 2 by the same operation as above.
At the same time, since the output of the record number counting section 5 is "2", "2" is stored in the register 59, and therefore, the second undefined data compression code (00) ₁₆ This time, two will be added.

Now, from the data compression unit 1 to the 35th address to the 39th address
Data stored at address (D, D, E,
(83) ₁₆ , F) are sent and stored in those addresses of the data buffer 6, and then the undefined data compression code generation unit 3 is activated by the data compression record end signal 13 from the record data end determination unit 2. When activated and the first undefined data compression code (80) ₁₆ is output, it is stored at the 40th address. At this time, at the timing of the data compression record end signal 13, the contents of the adder 48 in FIG. When the preset signal 31 from the undefined data compression code generating section 3 becomes "1", the counter 45 counts down.
Then, when the second and third first undefined data compression codes (80) ₁₆ are sent from the undefined data compression code generator 3, these are sent to the data buffer 6.
is stored in the 41st and 42nd addresses of the signal 3.
1 becomes "1" again, the counter 45
is counted down again, and this operation continues until three second undefined data compression codes are generated from the undefined data compression code generator 3, and the last second undefined data compression code is counted down as the second undefined data compression code. As shown in FIG. 4, when the data is stored at the 45th address of the data buffer 6, the output of the counter 45 becomes "1" and one input of the AND circuit 46 becomes "1". Since the output of is “1”, the AND circuit 46
The output of becomes "1". Therefore, the recording control device 8
At this time, a signal 33 indicating that storage of one new record has been completed is output, and the value "45" of the counter 42 at that time is latched into the register 47.

When the signal 33 becomes "1", the recording control device 8 converts the data from the first address to the 45th address of the data buffer 6 into one new one.
The data is read as a record via the record compression output data line 26 and recorded on a magnetic tape.

FIG. 5 is a diagram showing a state in which a plurality of compressed records are included in one record and recorded on a magnetic tape using the data compression method of the present invention, and CL1 to CL7 are compressed records, N is an undefined data compression code. In addition, as mentioned above, the maximum capacity of the data buffer 6 is set to a capacity commensurate with the maximum tape length that can be continuously written to the magnetic tape, and the monitoring data of the data buffer control unit 4 is set so that data as close to that range as possible is stored. Since the amount is set, the capacity of one record is not limited to the number of compressed records included therein, but is the capacity that provides the most efficient use of the recording medium. As can be seen from a comparison with FIG. 6(f) in which recording is performed using a conventional compression mechanism, the use efficiency of the recording medium can be improved as the gap between records is reduced. Each compressed record recorded on the magnetic tape as described above is separated using the undefined data compression code as a delimiter when reading the record containing it, and is restored to the original record by the data decompression mechanism. be done. At this time, the number of second undefined data compression codes corresponds to the number of the compression record in the record.

Although one embodiment of the present invention has been described above,
The present invention is not limited only to the above embodiments, and various other additions and changes are possible. For example, in the above embodiment, the data amount over signal 14 from the data buffer control unit 4 causes the recording control device 8 to stop sending out the next record, but instead, the record storage end signal 33
The sending of the next record may be stopped by the following. It is also possible to provide a plurality of data buffers 6 and to switch to another data buffer when a new record is generated and stored in one data buffer. Furthermore, the compression method of the present invention is applicable not only to magnetic tape devices but also to magnetic disk devices and other storage devices.

〔Effect of the invention〕

As explained above, according to the data record compression method of the present invention, a plurality of compressed records separated by undefined data compression codes are joined together to form one new record. This method has the effect of reducing non-data areas such as gaps between records on a recording medium compared to the conventional method in which one record is composed of records, and improving the usage efficiency of the recording medium.

Furthermore, since two types of undefined data compression codes are used and the number of the compressed record in the record is represented by the second undefined data compression code, searching using the record number in the record as a key becomes easy.

[Brief explanation of the drawing]

1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of an embodiment of the data buffer control section 4, FIG. 3 is a block diagram of an embodiment of the undefined data compression code generation section 3, and FIG. 4 is a block diagram of an embodiment of the undefined data compression code generation section 3. is data buffer 6
FIG. 5 is a diagram illustrating an example of a recording format according to the present invention, and FIG. 6 is a diagram illustrating a conventional system. In the figure, CP...data record compression mechanism,
1... Data compression section, 2... Record data end determination section, 3... Undefined data compression code generation section,
4... Data buffer control unit, 5... Record number counting unit, 6... Data buffer, 7... Data selector, 8... Recording control device, 9... Magnetic tape device.

Claims (1)

[Scope of Claims] 1. Data compression means for generating compressed records by performing compression processing on a record-by-record basis; counting means for counting the record number of the record currently being processed; undefined data compression code generation means for generating one undefined data compression code and a second undefined data compression code according to the count value of the counting means; a compressed record generated by the data compression means; a data buffer for storing first and second undefined data compression codes generated by the undefined data compression code generation means; A predetermined number of first undefined data compression codes to be stored in the data buffer and generated by the undefined data compression code generation means after the address next to the storage address.
and a number of second undefined data compression codes corresponding to the count value are executed for a plurality of records until a predetermined amount or more of data is stored in the data buffer. . A data record compression method comprising: means for converting the contents stored in the data buffer at the time when the predetermined amount of data or more is stored into one new record.