Improve libdeflate's worst-case performance decompressing malicious
DEFLATE streams by about 14x, bringing it within a factor of about 2x of
zlib, by skipping rebuilding the decode tables for the static Huffman
codes when they're already loaded into the decompressor.
This improves performance decompressing a stream of all empty static
Huffman blocks from about 0.36 MB/s to 175 MB/s, or the original
reproducer given on the Github issue from about 3.3 MB/s to 219 MB/s.
A regression test is added for these cases as well as the empty dynamic
Huffman blocks case to verify worst-case performance comparable to zlib.
Resolves https://github.com/ebiggers/libdeflate/issues/33
Make it compatible with the new code organization, make it run the
test_checksums program for each implementation, and run each
implementation in both 64-bit and 32-bit modes.
When the block splitting algorithm was implemented, it became possible
for the compressor to use longer blocks, up to ~300KB. Unfortunately it
was overlooked that this can allow literal runs > 65535 bytes, while in
one place the length of a literal run was still being stored in a u16.
To overflow the litrunlen and hit the bug the data would have had to
have far fewer matches than random data, which is possible but very
unusual. Fix the bug by reserving more space to hold the litrunlen, and
add a test for it.
I've decided to simplify and standardize the licensing status for the
library by using the MIT license instead of CC0 (a.k.a. "public
domain"). This eliminates the somewhat controversial 4(a) clause in
CC0, and, for this and other reasons, should (somewhat ironically) make
it easier for some people to use and contribute to the project.
Note: copyright will apply to new changes and to new versions of the
work as a whole. Of course, versions previously released as public
domain remain public domain where legally recognized.
* Bring in common headers and program code from xpack project
* Move program code to programs/
* Move library code to lib/
* GNU89 and MSVC2010 compatibility
* Other changes
