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.
A method of compressing letters adapted to store a letter in a specific bit and a memory unit includes compiling a set of 26 letters of the English alphabet and dividing it into two halves, which are respectively encoded as headers or tailers. Headers are stored in the specific bit, while tailers are stored in the memory unit, so as to reduce memory spaces. By using the method in combination with a speciaily designed data structure, 16 letters may be stored in 10 bits.
A method for reducing radio frequency interference from a high frequency serial bus by scrambling data signals and reducing the repetition of control signals. Beginning and ending control signals are provided with meaningless signals provided therebetween.
A preferred coding network uses an architecture called a Base-Filter-Resource (BFR) system. This approach integrates the advantages of format-specific compression into a general-purpose compression tool serving a wide range of data formats. Source data is parsed into blocks of similar data and each parsed blocks are compressed using a respectively selected compression algorithm. The algorithm can be chosen from a static model of the data or can be adaptive to the data in the parsed block. The parsed blocks are then combined into an encoded data file. For decoding, the process is reversed.
A block-wise adaptive statistical data compressor is disclosed that operates by replacing characters in a data block with super-character codewords comprising a variable length prefix and a fixed length index. The codewords are determined by treating a plurality of groups of characters as super-character groups and then adapting the codewords, for each data block, based upon the actual frequency of occurrence of the characters in each group. The super-character prefix value identifies the group to which a particular character belongs, and the index value identifies the individual character of the group. By grouping and indexing the characters into these super-character groups, the present invention models a particular data block using a fraction of the information generally required by a fixed statistical compressor. Also disclosed are multi-stage lossless block data compressors that include the block-wise adaptive statistical compressor and also include a clustering stage and a reordering stage. The clustering stage clusters like characters into similar locations within the data block, and the reordering stage reorders the data to generate an expected skew in the frequency distribution of characters in the data block so that the block can be more efficiently compressed by the block-wise adaptive statistical compressor.
