* Fix an out-of-bounds access to depth_histo in the
bit cost calculation function.
* Change type of distance symbol to uint16_t in block
splitter, because if all postfix bits are used, there
can be 520 distance symbols.
* Save the distance cache between meta-blocks at the
correct place. This fixes a roundtrip failure that
can occur when there is an uncompressed metablock
between two compressed metablocks.
* Fix a bug when setting lgwin to 24 in the encoder parameters
It ended up making metablocks larger than 24 bits in size.
* Fix out-of-bounds memory accesses in parallel encoder.
CreateBackwardReferences can read up to 4 bytes past end of
input if the end of input is before mask.
* Add missing header for memcpy() in port.h
* Cluster at most 64 histograms at a time in the first
round of clustering.
* Use a faster histogram cost estimation function.
* Don't compute the log2(total) multiple times in the
block splitter.
Disable all slow features for quality <= 9 (literal cost modeling,
dictionary, context modeling, advanced block splitting).
Change vector<Command> arguments of internal functions
to Command* and size_t.
The new mode can be used by setting the greedy_block_split
field of BrotliParams to true.
This commit moves all the meta-block processing code
into its own library and moves the meta-block encoding
code to brotli_bit_stream.cc from encode.cc
Changes suggested by @r-lyeh and @anthrotype.
- Use a portable simple PRNG instead of rand_r()
- add missing <assert.h> include
- disambiguate log2() argument type
- remove endian.h include from write_bits.h
The new interface of the backward reference search
function makes it possible to use it in a streaming
manner.
Using the advanced cost model and static dictionary
can be turned on/off by template parameters.
The distance short codes are now computed as part of
the backward reference search.
Added a faster version of the Hasher.
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:
* Format change: don't push distances representing static dictionary words to the distance cache.
* Fix decoder invalid memory access bug caused by building a non-complete Huffman tree.
* Add a mode parameter to the encoder interface.
* Use different hashers for text and font mode.
* Add a heuristics to the hasher for skipping non-compressible data.
* Exhaustive search of static dictionary during backward reference search.
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:
* Fixes to the spec.
* Change of code length code order.
* Use a 2-level Huffman lookup table in the decoder.
* Faster uncompressed meta-block decoding.
* Optimized encoding of the Huffman code.
* Detection of UTF-8 input encoding.
* UTF-8 based literal cost modeling for improved
backward reference selection.
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:
* Updated spec
* Changed Huffman code length alphabet to use run length codes more
efficiently, based on a suggestion by Robert Obryk
* Changed encoding of the number of Huffman code lengths (HLEN)
* Changed encoding of the number of Huffman trees (NTREES)
* Added support for uncompressed meta-blocks
