Method and apparatus for adaptive data compression
AssigneeCennoid Technologies, Inc.
InventorSpyros Panaoussis
Life of this patent
Estimating the term…
Abstract
The present invention relates to data compression systems and methods wherein text can be compressed by encoding repetitions of blocks of characters, or through a straight encoding scheme that converts eight-bit character values to four-bit character values by eliminating values for characters that are not valid word-starting characters or valid next-letter characters for a given preceding letter. Block compression is accomplished through the use of data structures that track the successive occurrence of valid block-repetition starting characters, and their lengths. Repeat-relative block compression is accomplished by detecting character sequences that can be expressed as the value of a previously-occurring character sequence plus or minus an offset.
Claims12
A method of compressing text contained in a data record wherein text characters are represented by numeric codes, comprising:
- scanning the data record;
- detecting a repeat-relative character sequence that can be expressed as the value of the code for a previously-occurring character sequence plus or minus a given number;
- converting the repeat-relative character sequence to a compressed code, said compressed code comprising a repeat-relative prefix, a sign flag, and an offset value, wherein said repeat-relative prefix identifies the type of coding, the sign flag indicates the sign of the offset value, and the offset value indicates the value to be added or subtracted from the value of the code for the previously-occurring character sequence.
A system for compressing text contained in a data record wherein text characters are represented by numeric codes, comprising:
- means for scanning the data record;
- means for detecting a repeat-relative character sequence that can be expressed as the value of the code for a previously-occurring character sequence plus or minus a given number;
- means for converting the repeat-relative character sequence to a compressed code, said compressed code comprising a repeat-relative prefix, a sign flag, and an offset value, wherein said repeat-relative prefix identifies the type of coding, the sign flag indicates the sign of the offset value, and the offset value indicates the value to be added or subtracted from the value of the code for the previously-occurring character sequence.
Dependencies are inferred from the claim text.