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Data Compression Using a Noun Vector Lookup Table

IP.com Disclosure Number: IPCOM000074501D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Blizard, VP: AUTHOR [+5]

Abstract

Storage size for handling received data is significantly reduced by inspecting that data as received using a Noun/Vector technique for data compression. Two tables are used for storage including a fixed size Noun Table of 1024 bytes or 256 fullwords, for instance, and a Vector Table that is variable in length.

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Data Compression Using a Noun Vector Lookup Table

Storage size for handling received data is significantly reduced by inspecting that data as received using a Noun/Vector technique for data compression. Two tables are used for storage including a fixed size Noun Table of 1024 bytes or 256 fullwords, for instance, and a Vector Table that is variable in length.

Input data is divided into four-byte segments, each being considered a unique noun. Each of these nouns is stored in the Noun Table and assigned a numerical value (0, 1, 2,...., 255) which is stored in the Vector Table. As the input data stream continues, each new noun is compared with those already stored in the table. When identical nouns are encountered only the one-byte vector representing the original need be stored, thus eliminating three bytes. The resultant Vector Table contains a one-byte vector for each four bytes of the input data in a given file.

Descriptive fields are added to each total record and each vector table within the record. These fields might typically include:. 1) a block descriptor word defining block length, 2) a fullword = last file compressed in this block, 3) a halfword to indicate if file is complete in this block, 4) a halfword noun count specifying the number of nouns in this block, 5) a Noun Table of fullwords, 6) a fullword file number to identify the vector table, 7) a halfword vector count = number of vectors in this table, and 8) the vector table, variable in length. Mul...