![]() Once literals and matches are identified, the encoder takes each and emits them to the bitstream. Effective compression relies on being able to encode the literals and references in fewer bits than the string being replaced. Standard compression schemes, such as DEFLATE, LZMA, LZJU90, and LZ4, use an LZSS-style kernel to parse the input string into a stream of literals and matches, a match being a back reference to a substring that can be subsituted at the cursor position. When we improve emCompress, we also improve the SEGGER Linker, which is a win all round! LZSS, the ubiquitous algorithm The company ethos is that we develop and use our own software, and therefore it is natural to use emCompress components as a way of compressing data sections held in flash that must be copied to RAM on startup. In discussing the linker and the future direction of our emCompress product, we examined the possibility of improving emCompress and, using that improvement, fold it into the SEGGER Linker. ![]() SMASH compresses as efficiently as DEFLATE, uses only a few words of decompressor state, and has an ultra-small, ultra-fast, ultra-simple decompressor. With some experimentation, the end result is a coding technique we named SMASH, the Small Microcontroller Advanced Super-High compression scheme. Limited state in RAM when decompressing.High compression ratio (uncompressed size divided by compressed size).To use no preset dictionary arra圜ache - cache to be used for allocating large arrays Throws: CorruptedInputException - if the first input byte is not 0x00 EOFException - file is truncated or corrupt IOException - may be thrown by in Since: 1.One of the things that is driven from the top in SEGGER is that we can always do better. Not satisfied with standard schemes, we wanted to optimize emCompress, SEGGER’s compression library, for: In the range dictSize - dictionary size as bytes, must be in the range In the range pb - number position bits, must be In the range lp - number of literal position bits, must be If the end marker is used in the LZMA stream lc - number of literal context bits, must be Parameters: in - input stream from which LZMA-compressed Int, int, byte) except that this also takes theĪrra圜ache argument. This is identical to LZMAInputStream(InputStream, long, int, int, To use no preset dictionary arra圜ache - cache to be used for allocating large arrays Throws: CorruptedInputException - if propsByte is invalid orīig for this implementation EOFException - file is truncated or corrupt IOException - may be thrown by in Since: 1.7 This is identical to LZMAInputStream(InputStream, long, byte, int,īyte) except that this also takes the arra圜acheĪrgument. Header) from in optionally with a preset dictionary. The first input byte is not 0x00 UnsupportedOptionsException - dictionary size or uncompressed size is too Throws: CorruptedInputException - if propsByte is invalid or Position bits (lp), and position bits (pb) dictSize - dictionary size as bytes, must be in the range Values for literal context bits (lc), literal If the end marker is used in the LZMA stream propsByte - LZMA properties byte that has the encoded Parameters: in - input stream from which compressedĭata is read uncompSize - uncompressed size of the LZMA stream or -1 Of the data, this might allow saving some memory. The uncompressed size of the data even if a bigger dictionary There is no need to specify a dictionary bigger than ![]() Specifying a too big dictionary is waste of memory but decompression SpecifyingĪ too small dictionary size will prevent decompressing the stream. ![]() The dictionary size used when compressing is also needed. The number of literal context bits (lc), literal position bits (lp), The caller also needs to provide the LZMA properties byte that encodes If the end marker isn't used, the caller must know the exact "end of stream marker (EOS marker)" alias "end marker" present. The caller needs to know if the "end of payload marker (EOPM)" alias Creates a new input stream that decompresses raw LZMA data (no. ![]()
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