The following entry in the Free Pascal contributed units was modified: Name : Algorithm HRC<br><nobr>(Hashing + RLE Compression)</nobr> Author : Alex Vaneev Email : [EMAIL PROTECTED] Homepage : http://www.ru.freepascal.org FTP site : ftp://ftp.mosfilm.ru/pub/fpc/russian/fpchrc.rar Version : 1.0 Date : 2006-11-22 Category : File Handling Supported OS : ALL Description : In this archive you can find sources of a so called HRC-compressor and decompressor. HRC is a rather simple compression scheme that was basically derived from Lempel-Ziv scheme, but with one addition: classical LZ pair <offset, length> was changed to <length, offset, length>, where first <length> contains number of bytes to copy "as is" from input stream to output stream. <br><br> Two compression methods were implemented: fast and slow. Fast method uses hash table to find repeating patterns and thus works rather fast - almost equal to decompressor in speed. In slow scheme a binary AVL-tree was additionally used which considerably slowed down compression speed, but increased compression ratio. A byte-oriented RLE compression is also used during compression which often increases compression ratio a lot. In average, compression algorithm works rather effectively for any type of data.
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