Kbasic torrent code#
Kbasic torrent series#

Kbasic torrent code#

The variant uses an increased 64 kilobyte dictionary with a 16-bit length code (match lengths 3вЂ“65538 byte) and 14-bit distance code (30вЂ“31). The focus with non-zlib versions of an encoder has normally been to produce a more efficiently compressed and small encoded stream.Дeflate64 is a proprietary and undocumented extension of the protocol, supported by PKZIP version 2.50 and above. Differing implementations will likely produce variations on the final encoded bit-stream produced. Other Deflate encoders have been produced, all of which will also produce a compatible bitstream capable of being decompressed by any existing Deflate decoder. Options range from -0 (do not attempt compression, just store uncompressed) to -9 representing the maximum capability of the reference implementation in zlib/gzip. The zlib/gzip reference implementation allows the user to select from a sliding scale of likely resulting compression-level vs. Дuring the compression stage, it is the encoder that chooses the amount of time spent looking for matching strings. Note that for the match distance symbols 2вЂ“29, the number of extra bits can be calculated as.

30вЂ“31: not used, reserved and illegal but still part of the tree.

The distance tree contains space for 32 symbols: Based on the distance code read, further 'extra' bits may be read in order to produce the final distance.

286,287: not used, reserved and illegal but still part of the tree.ДЄ match length code will always be followed by a distance code.

257вЂ“285: combined with extra-bits, a match length of 3вЂ“258 bytes.

256: end of block вЂ“ stop processing if last block, otherwise start processing next block.

0вЂ“255: represent the literal bytes/symbols 0вЂ“255.The more likely a symbol has to be encoded, the shorter its bit-sequence will be.ДЄ tree is created which contains space for 288 symbols: The method used is Huffman coding which creates an unprefixed tree of non-overlapping intervals, where the length of each sequence is inversely proportional to the probability of that symbol needing to be encoded. The second compression stage consists of replacing commonly-used symbols with shorter representations and less commonly used symbols with longer representations. Relative back-references can be made across any number of blocks, as long as the distance appears within the last 32kB of uncompressed data decoded (termed the sliding window).Д«it reduction Main article: Huffman coding An encoded match to an earlier string consists of a length (3-258 bytes) and a distance (1-32768 bytes).

Kbasic torrent series#

Within compressed blocks, if a duplicate series of bytes is spotted (a repeated string), then a back- reference is inserted, linking to the previous location of that identical string instead.

Replacing symbols with new, weighted symbols based on frequency of use.Дuplicate string elimination Main article: LZ77 and LZ78.

The matching and replacement of duplicate strings with pointers.

Instructions to generate the necessary Huffman tree immediately follow the block header.Д¬ompression is achieved through two steps:

Most blocks will end up being encoded using method 10, the dynamic Huffman encoding, which produces an optimised Huffman tree customised for each block of data individually.

10: a compressed block complete with the Huffman table supplied.

01: a static Huffman compressed block, using a pre-agreed Huffman tree.

00: a stored/raw/literal section follows, between 5 bytes in length.

2-bits: Encoding method used for this block type:.0: there are more blocks to process after this one.1: this is the last-block in the stream.Each block is preceded by a 3- bit header: A Deflate stream consists of a series of blocks.