All source material within lib directory are BSD 2-Clause licensed. See LICENSE for details. The license is also repeated at the top of each source file.
The directory contains many files, but depending on project's objectives, not all of them are necessary.
The minimum required is lz4.c and lz4.h, which will provide the fast compression and decompression algorithm.
For more compression at the cost of compression speed, the High Compression variant lz4hc is available. It's necessary to add lz4hc.c and lz4hc.h. The variant still depends on regular lz4 source files. In particular, the decompression is still provided by lz4.c.
In order to produce files or streams compatible with lz4 command line utility, it‘s necessary to encode lz4-compressed blocks using the official interoperable frame format. This format is generated and decoded automatically by the lz4frame library. In order to work properly, lz4frame needs lz4 and lz4hc, and also xxhash, which provides error detection. (Advanced stuff : It’s possible to hide xxhash symbols into a local namespace. This is what liblz4 does, to avoid symbol duplication in case a user program would link to several libraries containing xxhash symbols.)
A more complex lz4frame_static.h is also provided. It contains definitions which are not guaranteed to remain stable within future versions. It must be used with static linking only.
Other files present in the directory are not source code. There are :