CN101667843B - Methods and devices for compressing and uncompressing data of embedded system - Google Patents

Abstract

The invention discloses a data compression method for an embedded system, which includes: determining the same byte string in the data to be compressed, using the same byte string except the first byte string distance and the number of identical bytes to replace the identical byte strings. The invention also discloses a data decompression method for an embedded system, which includes: when the compressed data contains a compressed identifier, obtain the distance and the number of bytes to replace the byte string, and obtain the distance and the number of bytes in the decompressed data at the distance Obtain the bytes of the number of bytes and fill them into the current decompressed data. The invention also discloses a device for realizing the aforementioned method. The present invention is especially suitable for the embedded system of byte stream transmission, and the repeated byte string of byte stream transmission in the embedded system is more again, therefore, data compression ratio is higher, thereby makes the CPU occupancy rate of embedded system be in lower level.

Description

Data compression and decompression method and device for embedded system

technical field

The invention relates to data compression technology, in particular to a data compression method and device for an embedded system, and a decompression method and device.

Background technique

In the process of data link transmission in the embedded system, when the data flow is very large, it will often lead to blockage of the link, and at the same time, it will have a very large impact on the single board for data reporting, greatly reducing the system capacity, and even cause the board to reset. For example, when reporting logs on an EVDO channel board in a Code Division Multiple Access (CDMA, Code Division Multiple Access) system, when the amount of data is large, there will be a large number of data packet loss phenomena, and when there are multiple data reporting options, due to The blockage of the link can easily lead to the reset of the board, which brings a lot of risks to the system, and also increases the difficulty for outsiders to locate the problem. In order to accurately locate the problem, realize the simultaneous reporting of multiple data items, and minimize the packet loss rate, it is proposed that when the log is reported, the data is compressed first, and then the data is decompressed at the receiving end. Thereby, the packet loss problem is reduced, and the congestion of the data transmission link is avoided. Since the traditional compression methods are all based on file compression, and are all compressed on the PC, regardless of the CPU usage, but in the embedded system, all data appears in the form of byte streams Yes, there is no way to compress and store in the form of files, only the buffered data stream can be compressed, and since data transmission is an uninterrupted process, it is necessary to consider the CPU occupancy rate, memory utilization rate, and also the compression rate . At present, there is no suitable technical solution for data compression specifically for embedded systems.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a data compression method and device for an embedded system, and a decompression method and device, which can well compress the byte stream in the embedded system and facilitate data transmission.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A data compression method for an embedded system, comprising:

Determine the same byte string in the data to be compressed, in the same byte string except the first byte string, use the distance from the same byte string and the number of the same byte to replace the same byte string.

Preferably, the method also includes:

When transmitting data, set flags for uncompressed data and compressed data respectively.

Preferably, the distance from the identical byte string and the number of identical bytes are encoded using Gamma encoding.

Preferably, said determining the same byte string in the data to be compressed includes:

The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then there is a byte string identical to the byte string before, then continue The sliding window is slid until the longest byte string identical to the previous byte string is determined, and the distance to the same byte string is determined.

Preferably, said determining the same byte string in the data to be compressed includes:

The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then determine the byte string that is the same as the byte string and the closest distance , and continue to slide the sliding window, and judge whether the byte in the next sliding window of the byte string that is the same as the byte string in the previous sliding window and the nearest byte string is the same as the byte string in the current sliding window, Determine the longest byte string with the same byte string, and judge whether the number of bytes in the longest byte string with the same byte string reaches the set threshold, and if it does not reach, judge whether there is still the same byte string as the first byte string Other byte strings identical to the byte strings in the same sliding window until the number of bytes of the longest byte string identical to the determined byte string reaches the set threshold; or it is determined that there is no byte string identical to the first byte string The byte strings in the same sliding window are the same as other byte strings, and the determined longest byte string is the same as the final identical byte string.

Preferably, the method also includes:

When determining that the byte string in the sliding window is different from the previous byte string, store the byte string in the node of the index linked list, record the offset of the same byte string as zero, and record the byte string The data stored in the corresponding address in the class table array is the sequence value of the node storing the byte string in the index linked list; when it is determined that the byte string in the sliding window is the same as the previous byte string, the word The byte string is stored in the node of the index linked list, the offset between the byte string and the current closest same byte string is used as the offset of the byte string, and the corresponding byte string is recorded in the class list array The data stored by the address is the sequence value of the node storing the byte string in the index linked list.

A data decompression method for an embedded system, comprising:

When the compressed data contains a compression mark, obtain the distance and the number of bytes that replace the byte string, and obtain the bytes with the number of bytes at the distance in the decompressed data, and fill them in the current decompressed data .

Preferably, said obtaining the distance and the number of bytes to replace the byte string includes:

Gamma encoding is used to decode the distance and the number of bytes replacing the byte string in the compressed data to obtain the distance and the number of bytes.

A data compression device for an embedded system, comprising:

a determining unit, configured to determine the same byte string in the data to be compressed; and

The compression unit is used to replace the same byte string by using the distance from the same byte string and the number of the same byte except for the first byte string in the same byte string.

Preferably, the device also includes:

The setting unit is used to set the identification bits for the uncompressed data and the compressed data respectively when transmitting data.

Preferably, the device also includes:

The encoding unit is used to encode the distance from the identical byte string and the number of identical bytes using Gamma encoding.

Preferably, the determination unit determines the same byte string in the data to be compressed, including:

The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then there is a byte string identical to the byte string before, then continue The sliding window is slid until the longest byte string identical to the previous byte string is determined, and the distance to the same byte string is determined.

Preferably, the determination unit determines the same byte string in the data to be compressed, including:

The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then determine the byte string that is the same as the byte string and the closest distance , and continue to slide the sliding window, and judge whether the byte in the next sliding window of the byte string that is the same as the byte string in the previous sliding window and the nearest byte string is the same as the byte string in the current sliding window, Determine the longest byte string with the same byte string, and judge whether the number of bytes in the longest byte string with the same byte string reaches the set threshold, and if it does not reach, judge whether there is still the same byte string as the first byte string Other byte strings identical to the byte strings in the same sliding window until the number of bytes of the longest byte string identical to the determined byte string reaches the set threshold; or it is determined that there is no byte string identical to the first byte string The byte strings in the same sliding window are the same as other byte strings, and the determined longest byte string is the same as the final identical byte string.

A data decompression device for an embedded system, comprising:

A determination unit, configured to trigger an acquisition unit when determining that the compressed data contains a compression identifier;

an acquisition unit, configured to acquire the distance and the number of bytes in place of the byte string; and

The decompression unit is configured to obtain the bytes of the number of bytes at the distance in the decompressed data, and fill them into the current decompressed data.

In the present invention, for the byte stream data of the embedded system, determine all the same byte strings in the data to be transmitted, and for the same byte string as before, use the distance and the same byte string as before. The number of bytes to replace the same byte string, because only two numbers replace the byte string, which greatly reduces the amount of data to be transmitted bytes, thus achieving the compression of byte stream data, when decompressing , for uncompressed bytes, just output directly; for compressed byte strings, decompress in reverse according to the compression method. The present invention is especially suitable for the embedded system of byte stream transmission, and the repeated byte string of byte stream transmission in the embedded system is more again, therefore, data compression ratio is higher, thereby makes the CPU occupancy rate of embedded system be in lower level.

Description of drawings

Fig. 1 is the schematic diagram of the data compression method of embedded system of the present invention;

Fig. 2 is the composition structure schematic diagram of the data compression device of embedded system of the present invention;

FIG. 3 is a schematic diagram of the composition and structure of the data interface compression device of the embedded system of the present invention.

Detailed ways

The basic idea of the present invention is: for the byte stream data of the embedded system, all identical byte strings are determined in the data to be transmitted, and for the same byte strings as before, use the same byte strings as before. The distance and the same number of bytes are used to replace the same byte string. Since only two numbers are used to replace the byte string, the amount of data to be transmitted is greatly reduced, thereby achieving the compression of byte stream data. , when decompressing, for uncompressed bytes, just output directly, and for compressed byte strings, decompress in reverse according to the compression method. The present invention is especially suitable for the embedded system of byte stream transmission, and the repeated byte string of byte stream transmission in the embedded system is more again, therefore, data compression ratio is higher, thereby makes the CPU occupancy rate of embedded system be in lower level.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail by citing the following embodiments and referring to the accompanying drawings.

First of all, explain the compression principle adopted by the present invention, and take the character string "abcdef1234abcdeki1234" as an example to illustrate. For this character string, find out the byte string with the same content, and the part enclosed by "()" below is the byte string The same part, such as: abcdef1234(abcde)ki(1234). The present invention uses a pair of information such as the distance between the same byte string and the number (or length) of the same character to replace the same byte string, as the above byte string can be expressed as: abcdef1234(10,5)ki( 11, 4), wherein, "10" in "(10, 5)" is the distance between the same byte string and the current position, and "5" is the number (or length) of the same byte string. Similarly, "11" in "(11, 4)" is the distance between the same byte string and the current position, and "4" is the number of the same byte string. Since the distance between the same byte strings and the same byte number are much smaller than the size of the replaced byte string, the byte strings in the transmitted byte stream are compressed.

The essence of the technical solution of the present invention is further clarified through specific examples below.

Fig. 1 is the schematic diagram of the data compression method of the embedded system of the present invention, as shown in Fig. 1, the present invention takes the byte stream "abcdef1234abcki123abcde1234" as an example, and elaborates the substantive scheme of the present invention's data compression.

As shown in Figure 1, an index linked list for storing byte strings is set for the byte stream to be compressed, and a class table array m_awSortTable[] for storing byte string matching status is set. When the data stored in this array is 0, it means The byte string in the current sliding window does not have the same byte string in the previous byte string, and when the data stored in the class table array m_awSortTable[] is not 0, it means that the byte string in the current sliding window is in The previous byte string has the same byte string as it. The storage address of the byte string matching state in the class table array is determined according to the content of the specific byte string in the sliding window, which will be described in detail below. The size of the sliding window in this example is 2 bytes, and the size of the sliding window can be set arbitrarily according to specific needs, such as setting the size to 3 or 4 bytes.

Start from the beginning of the byte stream to traverse the entire byte stream according to the size of the sliding window, first find the "ab" 2-byte string, and calculate the storage address of the matching state of the "ab" byte string in m_awSortTable[], specifically, by "a×256+b" to determine, "a×256+b" is equivalent to determine the Hash value of the "ab" byte string, by searching m_awSortTable[a×256+b], confirm that it is 0, because there is currently no If there is a byte string identical to (matching) the "ab" byte string, insert "ab" into node 1 of the index list, and assign values to wOffSet, wSameOffSet, and wnext corresponding to node 1, that is, all are 0, wOffSet indicates the offset between the current byte string and the most recent same byte string, wSameOffSet indicates whether the current byte string is a byte string of the same byte, that is, to determine whether the current byte string is similar to "aa ", "bb", "22" and other byte strings with the same byte. In this example, it is a non-byte string with the same byte. 1; wnext is the offset between the same byte string, and in the present invention, it is to determine the offset (or distance) with the previous nearest byte string, because there is no identical byte string, so , the wnext is 0. Modify m_awSortTable[a×256+b]=1, indicating that “ab” is inserted into node 1 of the index linked list.

Make the sliding window slide back one byte, the sliding window is currently a "bc" 2-byte string, determine whether there is still no matching byte string in the previous byte string, in the same way as "ab", set " bc" is inserted into node 2 of the index linked list, wherein wOffSet=0, wSameOffSet=0, wnext=0 corresponding to node 2, it should be noted that, at this time, m_awSortTable[b×256+c]=2 (the previous value was empty , which is 0).

Keep sliding the sliding window backward until the next "ab" 2-byte string appears in the sliding window. By calculating the address of the table-like array of the "ab" byte string, it is found that m_awSortTable[a×256+b] is not 0, Prove that the "ab" byte string has appeared once before, and by querying m_awSortTable[a×256+b]=1, we can know that the byte string identical to this byte string is stored in node 1 of the index linked list, at this time Starting from the two identical byte strings "ab", slide the sliding window after the two identical byte strings, compare the byte strings in the two sliding windows one by one in the aforementioned manner, until they are different, and obtain the largest For the same byte string, for this example, three identical bytes "abc" are determined. And calculate the node number from the 11th node (the second byte string "abc" or "ab" stored in the index linked list) and the first node (the first byte string "abc" or "ab" "The node number stored in the index linked list) difference, the distance between the two byte strings is "10", and the number of bytes (or length) of the same byte string is "3". And m_awSortTable[a×256+b]=11 (11 is the node number corresponding to the second byte string “ab”).

Then continue to slide the sliding window. When the "12" 2-byte string appears in the sliding window, m_awSortTable[1×256+2]=7 is found, indicating that the "12" byte string has appeared once in the previous byte stream , with the method of the previous step, get the largest identical character, three repeated characters "123" and the distance between them "9".

Continue to slide the sliding window. When the "ab" 2-byte string appears again in the sliding window, m_awSortTable[a×256+b]=11 is found, indicating that the "ab" byte string has appeared once in the previous byte stream. Utilize the above method to obtain the byte string (the distance between the two, the byte length of the same byte string) with the node 11, and at this time find that the wnext=1 corresponding to the node 11 shows that there is also an "ab" at the node 1 "byte string, at this time, the current position of the byte stream to the position of node 1 will be obtained in the above steps at the same time (the distance between the two, the byte length of the same byte string), and the "same" obtained by comparing twice The byte length of the byte string", the largest one being the same byte string as finalized. In this example, the byte length of the same byte string between the current byte string "ab" and the byte string in node 1 of the index linked list is large, which is "5", then use (18, 5) to replace the word The stanza string "abcde".

It should be noted that, when the sliding window slides to "ab" at node 19, the present invention may first perform byte string matching on the byte string where node 11 is located, and determine "the byte length of the same byte string" If it is "3", then it is compared with the set threshold (such as being set to 4), and when it is greater than or equal to the threshold, the maximum number of identical bytes of the nearest identical byte string is directly used as the final maximum number of identical bytes; determine When the same byte length is less than the set threshold, determine whether there is the same byte string ("ab") before the nearest identical byte string ("ab"), and determine the next closest identical byte string The "byte length of the same byte string" of the section string, and compare it with the set threshold, if it is less than the set threshold, continue to search whether there is the same byte string ("ab") as in the current sliding window before, Until the "byte length of the same byte string" greater than the set threshold is found, or all the byte streams are searched, if all the byte streams are searched, the "same byte string" greater than the set threshold is still not found The byte string of the "byte length of the same byte string", then the subsection string of the largest "byte length of the same byte string" found is used as the final identical byte string.

The following describes how the present invention realizes compression. Suppose there is a section of byte stream "abcdef1234abcki123abcde1234abcki123abcde1234". When the sliding window points to the beginning of the byte stream, the 2-byte string "ab" is taken out. As can be seen from the sliding window sliding process in Figure 1, this When "ab" is a 2-byte string, there is no repetition, so first write bit'0' to the output buffer, and then write 'a'.

The sliding window continues to slide one byte backward, and the 2-byte string "bc" is taken out. At this time, the 2-byte string of "bc" also has repetitions, so it is also written into the output buffer first, bit'0', and then write Enter 'b'. Add a node "ab" to the index linked list, that is, node 1 in the index linked list in FIG. 1 .

The sliding window continues to slide one byte back, and takes out the 2-byte string "cd". At this time, the "cd" 2-byte string also has repetitions, so it is also written into the output buffer first, bit'0', and then write Enter 'c'. Then add "bc" to the last node of the index linked list, that is, node 2 of the index linked list in FIG. 1 .

By analogy, when the sliding window moves to "4a", the 2-byte string "4a" is taken out. At this time, the "4a" 2-byte string has no repetition, so it is also written into the output buffer first and bit'0 ', then write '4'. Then add a node "34" to the index linked list, that is, node 9 of the index linked list in FIG. 1 .

The sliding window continues to slide down one byte, and the 2-byte string "ab" is taken out. At this time, the "ab" 2-byte string, when traversing in the index table, is found to have appeared before. And through its index node, you can find its wOffSet offset. Thereby, the position where it appears can be located, and the "distance 10" and "the byte length of the same byte string 3" can be calculated. At this time, first write bit '1' into the output buffer, and then first perform Gamma (Gamma) encoding on "distance 10" and "byte length of the same byte string" and then output them to the buffer. Then add nodes "4a" and "ab" to the index linked list, that is, nodes 10 and 11 of the index linked list in FIG. 1 . When the sliding window is moved to "12", the processing is the same as "ab".

The following is a brief introduction to Gamma coding. Assuming that x is coded, let q=Int(log ₂ x), then the first part of the code is q 1s plus a 0, and the second part is a q-bit long binary number whose value is equal to x- ^2q . The correspondence between ordinary values and Gamma coded values is shown in Table 1:

value 1 2 3 4 5 6 7 8 9 coded value 0 10 0 10 1 110 00 110 01 110 10 110 11 111 0000 111 0001

Table 1

When the sliding window slides down to another "ab", the 2-byte string "ab" is taken out. At this time, the "ab" 2-byte string is traversed in the index table, and it is found that it has appeared before. And through its index node 11, its wOfffSet offset can be found. So as to be able to locate the position where it appears, calculate its distance 9 and the same length 3. At this time, it is found that the wNext value of the index node is not 0, which means that "ab" appeared once before node 11. Therefore, the index position where "ab" appears is obtained through wNext, that is, node 1. Calculate its distance 19, the same length is 5, which is larger than the calculated length with node 11. Then get the value of wNext of node 1 to be 0, which means that node 1 does not have the same byte string "ab" before. So at this time, first write bit'1' into the output buffer, and then first perform Gamma encoding on "distance" and "same length" and then output it to the buffer. Then add nodes "3a", "ab", "bc", and "cd" to the index linked list, that is, nodes 18, 19, 20, and 21 of the index linked list in FIG. 1 .

依此类推，最后压缩后的数据为“30988c664329986232198d300d669c6e”(对应的ASCII码)，压缩前数据的ASCII码是“616263646566313233346162636b693132336162636465313233346162636b69313233616263646531323334”。 The node stream data is thus greatly compressed.

To give an example of decompression:

Decompression is a reverse process, relatively simple. Assuming that the compressed data is "30988c664329986232198d300d669c6e" (corresponding ASCII code), first point the pointer to the beginning, take out the first bit, which is '0', and obtain the next 8 bits are the characters that need to be output directly. To get "61" (ASCII code), that is, the character 'a', then continue to read a "bit" and find it is still '0', continue to write down the next 8 "bits", that is, get "62" (ASCII code), that is, the character 'b', and so on, you can read "cdef1234". When the character '4' is finished, read another bit and find it is '1'. At this time, go all the way When the bit is read out until it is not '1', q 1s are obtained, and then a 0 is read down, and then the q bit value is read out. At this time, the Gamma coding formula is used to invert, and the data value encoded before compression can be obtained, so as to read the length of the repetition; then read down the bit length that needs to be stored for the distance between the two before compression, that is, read The distance between the two, and then you can start copying data to the current location for output. By analogy, all the data can be decompressed.

Fig. 2 is a schematic diagram of the composition structure of the data compression device of the embedded system of the present invention, as shown in Fig. 2, the data compression device of the embedded system of the present invention comprises a determination unit 20 and a compression unit 21, wherein the determination unit 20 is used to determine The same byte string in the data to be compressed; the compression unit 21 is used to replace the same byte string with the distance from the same byte string and the number of the same byte except the first byte string the same byte string.

As shown in FIG. 2 , the data compression device of the embedded system of the present invention further includes a setting unit 22 for setting identification bits for uncompressed data and compressed data respectively when transmitting data.

As shown in FIG. 2 , the data compression device of the embedded system of the present invention further includes an encoding unit 23 for encoding the distance from the identical byte string and the number of identical bytes using Gamma encoding.

Determining unit 20 determines the same byte string in the data to be compressed, including: the set sliding window slides byte by byte from the first byte of the data to be compressed, according to the byte in the sliding window after each slide String determines the address of the byte string in the class list array, and judges whether the data stored in the address is zero. If it is zero, there is no byte string identical to the byte string before. When it is not zero, Then there is a byte string identical to the byte string before, then continue to slide the sliding window until the longest byte string identical to the previous byte string is determined, and the length of the same byte string is determined. distance.

Alternatively, the determining unit 20 determines the same byte string in the data to be compressed, including: the set sliding window slides byte by byte from the first byte of the data to be compressed, and according to the The byte string determines the address of the byte string in the class table array, and judges whether the data stored in the address is zero. If it is zero, there is no byte string identical to the byte string before, and it is not zero , then determine the byte string that is the same as the byte string and the closest to the byte string, and continue to slide the sliding window to determine the next byte string that is the same as the byte string in the previous sliding window and the closest Whether the byte in the sliding window is the same as the byte string in the current sliding window, determine the longest byte string with the same byte string, and determine whether the number of bytes in the longest byte string with the same byte string reaches Set the threshold, and when it is not reached, judge whether there are other byte strings that are identical to the byte strings in the sliding window that are the same as the first byte string, until the determined byte string is the same as the longest byte string The number of bytes reaches the set threshold; or it is determined that there is no other byte string that is the same as the byte string in the sliding window that is the same as the first byte string, and the longest byte string that is the same as the determined byte string as the final same byte string.

Those skilled in the art should understand that the data compression device of the embedded system shown in Figure 2 of the present invention is designed for realizing the data compression method of the aforementioned embedded system, and the realization functions of each processing unit in the device shown in Figure 2 can be It can be understood with reference to the relevant descriptions in the aforementioned method for reducing mutual interference of multiple carriers that the functions of each unit may be implemented by a program running on a processor, or may be implemented by a corresponding logic circuit.

Fig. 3 is a schematic diagram of the composition structure of the data compression device of the embedded system of the present invention, as shown in Fig. 3, the data compression device of the embedded system of the present invention comprises a determination unit 30, an acquisition unit 31 and a decompression unit 32, wherein the determination unit 30 is used to trigger the acquisition unit 31 when it is determined that the compressed data contains a compression identifier; the acquisition unit 31 is used to acquire the distance and the number of bytes in place of the byte string; Obtain the bytes of the number of bytes and fill them into the current decompressed data.

Those skilled in the art should understand that the data decompression device of the embedded system shown in Figure 3 of the present invention is designed for realizing the data compression method of the aforementioned embedded system, and the realization functions of each processing unit in the device shown in Figure 3 It can be understood with reference to the related descriptions in the aforementioned method for reducing mutual interference of multiple carriers, that the functions of each unit can be realized by a program running on a processor, or can be realized by a corresponding logic circuit.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (11)

1. A data compression method for an embedded system, comprising: Determine the same byte string in the data to be compressed, in the same byte string except the first byte string, use the distance from the same byte string and the number of the same byte to replace the same byte string; Wherein, the determination of the same byte string in the data to be compressed includes: The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then there is a byte string identical to the byte string before, then continue The sliding window is slid until the longest byte string identical to the previous byte string is determined, and the distance to the same byte string is determined. 2. The method according to claim 1, characterized in that the method further comprises: When transmitting data, set flags for uncompressed data and compressed data respectively. 3. The method according to claim 1, wherein the distance from the same byte string and the number of the same byte are encoded using a Gamma encoding method. 4. The method according to claim 1, wherein said determining the same byte string in the data to be compressed comprises: The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then determine the byte string that is the same as the byte string and the closest distance , and continue to slide the sliding window, and judge whether the byte in the next sliding window of the byte string that is the same as the byte string in the previous sliding window and the nearest byte string is the same as the byte string in the current sliding window, Determine the longest byte string with the same byte string, and judge whether the number of bytes in the longest byte string with the same byte string reaches the set threshold, and if it does not reach, judge whether there is still the same byte string as the first byte string Other byte strings identical to the byte strings in the same sliding window until the number of bytes of the longest byte string identical to the determined byte string reaches the set threshold; or it is determined that there is no byte string identical to the first byte string The byte strings in the same sliding window are the same as other byte strings, and the determined longest byte string is the same as the final identical byte string. 5. according to the described method of claim 1 or 4, it is characterized in that, described method also comprises: When determining that the byte string in the sliding window is different from the previous byte string, store the byte string in the node of the index linked list, record the offset of the same byte string as zero, and record the byte string The data stored in the corresponding address in the class table array is the sequence value of the node storing the byte string in the index linked list; when it is determined that the byte string in the sliding window is the same as the previous byte string, the word The byte string is stored in the node of the index linked list, the offset between the byte string and the current closest same byte string is used as the offset of the byte string, and the corresponding byte string is recorded in the class table array The data stored by the address is the sequence value of the node storing the byte string in the index linked list. 6. A data decompression method for an embedded system, comprising: When the compressed data contains a compression mark, obtain the distance and the number of bytes that replace the byte string, and obtain the bytes with the number of bytes at the distance in the decompressed data, and fill them in the current decompressed data ; Specifically include: according to the address of the byte string in the class table array, judge whether the data stored in the address is zero, if it is zero, then directly output the corresponding character; Deduce the encoded data value before compression, read the length of the repetition, and then read the bit length that needs to be stored for the distance between the replacement byte string and the same byte string before compression, that is, read the distance between the two Copy the corresponding data to the current location. 7. A data compression device for an embedded system, comprising: a determining unit, configured to determine the same byte string in the data to be compressed; and A compression unit for replacing the same byte string with the distance from the same byte string and the number of the same bytes except for the first byte string in the same byte string; Wherein, the determination unit determines the same byte string in the data to be compressed, including: The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then there is a byte string identical to the byte string before, then continue The sliding window is slid until the longest byte string identical to the previous byte string is determined, and the distance to the same byte string is determined. 8. The device according to claim 7, further comprising: The setting unit is used to set the identification bits for the uncompressed data and the compressed data respectively when transmitting data. 9. The device according to claim 7, further comprising: The encoding unit is used to encode the distance from the identical byte string and the number of identical bytes using Gamma encoding. 10. The device according to claim 7, wherein the determination unit determines the same byte string in the data to be compressed, comprising: The set sliding window slides byte by byte from the first byte of the data to be compressed, determines the address of the byte string in the class table array according to the byte string in the sliding window after each slide, and judges the Whether the data stored in the above address is zero, if it is zero, there is no byte string identical to the byte string before, if it is not zero, then determine the byte string that is the same as the byte string and the closest distance , and continue to slide the sliding window, and judge whether the byte in the next sliding window of the byte string that is the same as the byte string in the previous sliding window and the nearest byte string is the same as the byte string in the current sliding window, Determine the longest byte string with the same byte string, and judge whether the number of bytes in the longest byte string with the same byte string reaches the set threshold, and if it does not reach, judge whether there is still the same byte string as the first byte string Other byte strings identical to the byte strings in the same sliding window until the number of bytes of the longest byte string identical to the determined byte string reaches the set threshold; or it is determined that there is no byte string identical to the first byte string The byte strings in the same sliding window are the same as other byte strings, and the determined longest byte string is the same as the final identical byte string. 11. A data decompression device for an embedded system, characterized in that, comprising: A determination unit, configured to trigger an acquisition unit when determining that the compressed data contains a compression identifier; an acquisition unit, configured to acquire the distance and the number of bytes in place of the byte string; and The decompression unit is used to obtain the bytes of the number of bytes at the distance in the decompressed data and fill them into the current decompressed data; The acquisition unit is further used to deduce the encoded data value before compression through the Gamma encoding formula, read the length of the repetition, and then read the distance between the replacement byte string and the same byte string before compression The bit length to be stored, that is, the distance between the two reads; The decompression unit is further used to judge whether the data stored in the address is zero according to the address of the byte string in the class table array, and if it is zero, then directly output the corresponding character; if it is not zero, then Reverse the Gamma coding formula to obtain the data value encoded before compression, and copy the corresponding data according to the length of the replacement byte string read by the acquisition unit and the distance between the replacement byte string and the same byte string before to the current location.

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