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  that zstd does not use. Not all unused functions are hidden, but they can be if needed.
  Currently, this macro will hide function definitions in FSE and HUF that use an excessive
  amount of stack space.

- The build macro `ZSTD_NO_INTRINSICS` can be defined to disable all explicit intrinsics.
  Compiler builtins are still used.

- The build macro `ZSTD_DECODER_INTERNAL_BUFFER` can be set to control
  the amount of extra memory used during decompression to store literals.
  This defaults to 64kB.  Reducing this value reduces the memory footprint of
  `ZSTD_DCtx` decompression contexts,
  but might also result in a small decompression speed cost.

- The C compiler macros `ZSTDLIB_VISIBLE`, `ZSTDERRORLIB_VISIBLE` and `ZDICTLIB_VISIBLE`
  can be overridden to control the visibility of zstd's API. Additionally,
  `ZSTDLIB_STATIC_API` and `ZDICTLIB_STATIC_API` can be overridden to control the visibility
  of zstd's static API. Specifically, it can be set to `ZSTDLIB_HIDDEN` to hide the symbols
  from the shared library. These macros default to `ZSTDLIB_VISIBILITY`,
  `ZSTDERRORLIB_VSIBILITY`, and `ZDICTLIB_VISIBILITY` if unset, for backwards compatibility
  with the old macro names.

#### Windows : using MinGW+MSYS to create DLL

DLL can be created using MinGW+MSYS with the `make libzstd` command.
This command creates `dll\libzstd.dll` and the import library `dll\libzstd.lib`.
The import library is only required with Visual C++.
The header file `zstd.h` and the dynamic library `dll\libzstd.dll` are required to
compile a project using gcc/MinGW.
The dynamic library has to be added to linking options.
It means that if a project that uses ZSTD consists of a single `test-dll.c`
file it should be linked with `dll\libzstd.dll`. For example:
```
    gcc $(CFLAGS) -Iinclude/ test-dll.c -o test-dll dll\libzstd.dll
```
The compiled executable will require ZSTD DLL which is available at `dll\libzstd.dll`.


#### Advanced Build options

The build system requires a hash function in order to
separate object files created with different compilation flags.
By default, it tries to use `md5sum` or equivalent.
The hash function can be manually switched by setting the `HASH` variable.
For example : `make HASH=xxhsum`
The hash function needs to generate at least 64-bit using hexadecimal format.
When no hash function is found,
the Makefile just generates all object files into the same default directory,
irrespective of compilation flags.
This functionality only matters if `libzstd` is compiled multiple times
with different build flags.

The build directory, where object files are stored
can also be manually controlled using variable `BUILD_DIR`,
for example `make BUILD_DIR=objectDir/v1`.
In which case, the hash function doesn't matter.


#### Deprecated API

Obsolete API on their way out are stored in directory `lib/deprecated`.
At this stage, it contains older streaming prototypes, in `lib/deprecated/zbuff.h`.
These prototypes will be removed in some future version.
Consider migrating code towards supported streaming API exposed in `zstd.h`.


#### Miscellaneous

The other files are not source code. There are :

 - `BUCK` : support for `buck` build system (https://buckbuild.com/)
 - `Makefile` : `make` script to build and install zstd library (static and dynamic)
 - `README.md` : this file
 - `dll/` : resources directory for Windows compilation
 - `libzstd.pc.in` : script for `pkg-config` (used in `make install`)