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Definitions which are not guaranteed to remain stable in future versions,
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are protected behind macros, such as `LZ4_STATIC_LINKING_ONLY`.
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As the name implies, these definitions can only be invoked
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As the name strongly implies, these definitions should only be invoked
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in the context of static linking ***only***.
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Otherwise, dependent application may fail on API or ABI break in the future.
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The associated symbols are also not present in dynamic library by default.
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The associated symbols are also not exposed by the dynamic library by default.
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Should they be nonetheless needed, it's possible to force their publication
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by using build macro `LZ4_PUBLISH_STATIC_FUNCTIONS`.
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by using build macros `LZ4_PUBLISH_STATIC_FUNCTIONS`
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and `LZ4F_PUBLISH_STATIC_FUNCTIONS`.
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The following build macro can be selected at compilation time :
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The following build macro can be selected to adjust source code behavior at compilation time :
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- `LZ4_FAST_DEC_LOOP` : this triggers the optimized decompression loop.
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This loops works great on x86/x64 cpus, and is automatically enabled on this platform.
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It's possible to enable or disable it manually, by passing `LZ4_FAST_DEC_LOOP=1` or `0` to the preprocessor.
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- `LZ4_FAST_DEC_LOOP` : this triggers a speed optimized decompression loop, more powerful on modern cpus.
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This loop works great on `x86`, `x64` and `aarch64` cpus, and is automatically enabled for them.
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It's also possible to enable or disable it manually, by passing `LZ4_FAST_DEC_LOOP=1` or `0` to the preprocessor.
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For example, with `gcc` : `-DLZ4_FAST_DEC_LOOP=1`,
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and with `make` : `CPPFLAGS+=-DLZ4_FAST_DEC_LOOP=1 make lz4`.
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Should this be a problem, it's generally possible to make the compiler ignore these warnings,
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for example with `-Wno-deprecated-declarations` on `gcc`,
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or `_CRT_SECURE_NO_WARNINGS` for Visual Studio.
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Another method is to define `LZ4_DISABLE_DEPRECATE_WARNINGS`
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before including the LZ4 header files.
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This build macro offers another project-specific method
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by defining `LZ4_DISABLE_DEPRECATE_WARNINGS` before including the LZ4 header files.
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- `LZ4_USER_MEMORY_FUNCTIONS` : replace calls to <stdlib>'s `malloc`, `calloc` and `free`
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by user-defined functions, which must be called `LZ4_malloc()`, `LZ4_calloc()` and `LZ4_free()`.
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User functions must be available at link time.
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- `LZ4_FORCE_SW_BITCOUNT` : by default, the compression algorithm tries to determine lengths
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by using bitcount instructions, generally implemented as fast single instructions in many cpus.
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In case the target cpus doesn't support it, or compiler intrinsic doesn't work, or feature bad performance,
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it's possible to use an optimized software path instead.
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This is achieved by setting this build macros .
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In most cases, it's not expected to be necessary,
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but it can be legitimately considered for less common platforms.
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- `LZ4_ALIGN_TEST` : alignment test ensures that the memory area
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passed as argument to become a compression state is suitably aligned.
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This test can be disabled if it proves flaky, by setting this value to 0.
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#### Miscellaneous
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Other files present in the directory are not source code. There are :
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Other files present in the directory are not source code. They are :
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- `LICENSE` : contains the BSD license text
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- `Makefile` : `make` script to compile and install lz4 library (static and dynamic)
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lib/README.md
