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EP0204992A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method for compressing and decompressing data

Assignee: International Business Machines Corp
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Filing: 1986-05-16
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Granted: —
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Expires: 2006-05-16
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Abstract

Abstract A compression and a decompression algorithm resides in a memory of a data processing system. The data processing system communicates to another data processing system via an input/output means and a telecommunications network. When a message, to be communicated to the other data processing system, is ready for transmission, the data processing system compresses the message data. A processor of the data processing system compresses the data using the compression algorithm stored in the memory of the data processing system. The compression algorithm: identifies a mask character in the data representing the most frequently occurring character in the data, develops a mask byte in association with the mask character, !the mask byte identifying the locations of the mask character in the data and identifying the locations of leach portion of a residual message associated with the data, and develops the residual message, the residual message representing the message data with the mask character extracted from the message data.

Inventors

  • 👤 Edward Larson Lawrence

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 11:32
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/3066

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 102 words
A method of compressing a set of data, comprising the steps of: identifying a mask character in said set of data representing the most frequently occurring character in said set of data; developing a mask byte identifying the locations of said mask character in said set of data and identifying the locations of each portion of a residual message associated with said set of data; developing a residual message of residual bytes, being said set of data having said mask character extracted therefrom; and concatenating said mask character, said mask byte, and said residual message to form the compressed set of data.
Claim 2
Independent Claim 102 words
A method of compressing a set of data, comprising the steps of: identifying a mask character in said set of data representing the most frequently occurring character in said set of data; developing a mask byte identifying the locations of said mask character in said set of data and identifying the locations of each portion of a residual message associated with said set of data; developing a residual message of residual bytes, being said set of data having said mask character extracted therefrom; and concatenating said mask character, said mask byte, and said residual message to form the compressed set of data.
Claim 3
Dependent Claim 19 words
A method wherein the compressed data is compressed one or several times according to the steps of claim 1.
Claim 4
Dependent Claim 33 words
A method wherein the compression according to claim 2 is repeated as long as the length of the compressed set of data becomes longer than the previous length of the set of data.
Claim 5
Independent Claim 28 words
A method according to one of the preceding claims wherein the characters are represented by eight Bit Bytes and the characters of one set are multiples of eight.
Claim 6
Independent Claim 26 words
A method according to one of the preceding claims wherein the compressed data are concatenated with a length indicator, denoting the actual length of the message.
Claim 7
Independent Claim 23 words
A method according to one of the preceding claims wherein the compressed data are concatenated with a modulus number, denoting a reference length.
Claim 8
Independent Claim 37 words
A method for decompressing a set of data comprising the steps of substituting the mask character for the 1-bits of the mask byte and the residual bytes for the 0-bits of the mask character or vice versa.
Claim 9
Independent Claim 37 words
A method for decompressing a set of data comprising the steps of substituting the mask character for the 1-bits of the mask byte and the residual bytes for the 0-bits of the mask character or vice versa.
Claim 10
Dependent Claim 19 words
A method according to claim 5 wherein in analogy to claim 2 decompressing is repeated once or several times.
Claim 11
Independent Claim 19 words
A system especially a computer system for compressing and/or decompressing working according to the methods of the preceding claims.

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