README.md in extlz4-0.3

- old
+ new
@@ -5,51 +5,100 @@
 not all of them are necessary.
 
 #### Minimal LZ4 build
 
 The minimum required is **`lz4.c`** and **`lz4.h`**,
-which provides the fast compression and decompression algorithm.
-They generate and decode data using [LZ4 block format].
+which provides the fast compression and decompression algorithms.
+They generate and decode data using the [LZ4 block format].
 
 
 #### High Compression variant
 
 For more compression ratio at the cost of compression speed,
 the High Compression variant called **lz4hc** is available.
-Add files **`lz4hc.c`**, **`lz4hc.h`** and **`lz4opt.h`**.
-The variant still depends on regular `lib/lz4.*` source files.
+Add files **`lz4hc.c`** and **`lz4hc.h`**.
+This variant also compresses data using the [LZ4 block format],
+and depends on regular `lib/lz4.*` source files.
 
 
-#### Frame variant, for interoperability
+#### Frame support, for interoperability
 
 In order to produce compressed data compatible with `lz4` command line utility,
-it's necessary to encode lz4-compressed blocks using the [official interoperable frame format].
+it's necessary to use the [official interoperable frame format].
 This format is generated and decoded automatically by the **lz4frame** library.
 Its public API is described in `lib/lz4frame.h`.
 In order to work properly, lz4frame needs all other modules present in `/lib`,
 including, lz4 and lz4hc, and also **xxhash**.
 So it's necessary to include all `*.c` and `*.h` files present in `/lib`.
 
 
 #### Advanced / Experimental API
 
-A complex API defined in `lz4frame_static.h` contains definitions
-which are not guaranteed to remain stable in future versions.
-As a consequence, it must be used with static linking ***only***.
+Definitions which are not guaranteed to remain stable in future versions,
+are protected behind macros, such as `LZ4_STATIC_LINKING_ONLY`.
+As the name implies, these definitions can only be invoked
+in the context of static linking ***only***.
+Otherwise, dependent application may fail on API or ABI break in the future.
+The associated symbols are also not present in dynamic library by default.
+Should they be nonetheless needed, it's possible to force their publication
+by using build macro `LZ4_PUBLISH_STATIC_FUNCTIONS`.
 
 
+#### Build macros
+
+The following build macro can be selected at compilation time :
+
+- `LZ4_FAST_DEC_LOOP` : this triggers the optimized decompression loop.
+  This loops works great on x86/x64 cpus, and is automatically enabled on this platform.
+  It's possible to enable or disable it manually, by passing `LZ4_FAST_DEC_LOOP=1` or `0` to the preprocessor.
+  For example, with `gcc` : `-DLZ4_FAST_DEC_LOOP=1`,
+  and with `make` : `CPPFLAGS+=-DLZ4_FAST_DEC_LOOP=1 make lz4`.
+
+- `LZ4_DISTANCE_MAX` : control the maximum offset that the compressor will allow.
+  Set to 65535 by default, which is the maximum value supported by lz4 format.
+  Reducing maximum distance will reduce opportunities for LZ4 to find matches,
+  hence will produce worse the compression ratio.
+  However, a smaller max distance may allow compatibility with specific decoders using limited memory budget.
+  This build macro only influences the compressed output of the compressor.
+
+- `LZ4_DISABLE_DEPRECATE_WARNINGS` : invoking a deprecated function will make the compiler generate a warning.
+  This is meant to invite users to update their source code.
+  Should this be a problem, it's generally possible to make the compiler ignore these warnings,
+  for example with `-Wno-deprecated-declarations` on `gcc`,
+  or `_CRT_SECURE_NO_WARNINGS` for Visual Studio.
+  Another method is to define `LZ4_DISABLE_DEPRECATE_WARNINGS`
+  before including the LZ4 header files.
+
+
+#### Amalgamation
+
+lz4 source code can be amalgamated into a single file.
+One can combine all source code into `lz4_all.c` by using following command:
+```
+cat lz4.c > lz4_all.c
+cat lz4hc.c >> lz4_all.c
+cat lz4frame.c >> lz4_all.c
+```
+(`cat` file order is important) then compile `lz4_all.c`.
+All `*.h` files present in `/lib` remain necessary to compile `lz4_all.c`.
+
+
 #### Windows : using MinGW+MSYS to create DLL
 
 DLL can be created using MinGW+MSYS with the `make liblz4` command.
 This command creates `dll\liblz4.dll` and the import library `dll\liblz4.lib`.
+To override the `dlltool` command  when cross-compiling on Linux, just set the `DLLTOOL` variable. Example of cross compilation on Linux with mingw-w64 64 bits:
+```
+make BUILD_STATIC=no CC=x86_64-w64-mingw32-gcc DLLTOOL=x86_64-w64-mingw32-dlltool OS=Windows_NT
+```
 The import library is only required with Visual C++.
 The header files `lz4.h`, `lz4hc.h`, `lz4frame.h` and the dynamic library
 `dll\liblz4.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 LZ4 consists of a single `test-dll.c`
 file it should be linked with `dll\liblz4.dll`. For example:
 ```
-    gcc $(CFLAGS) -Iinclude/ test-dll.c -o test-dll dll\liblz4.dll
+    $(CC) $(CFLAGS) -Iinclude/ test-dll.c -o test-dll dll\liblz4.dll
 ```
 The compiled executable will require LZ4 DLL which is available at `dll\liblz4.dll`.
 
 
 #### Miscellaneous