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+xxHash - Extremely fast hash algorithm
+======================================
+
+<!-- TODO: Update. -->
+xxHash is an Extremely fast Hash algorithm, running at RAM speed limits.
+It successfully completes the [SMHasher](https://code.google.com/p/smhasher/wiki/SMHasher) test suite
+which evaluates collision, dispersion and randomness qualities of hash functions.
+Code is highly portable, and hashes are identical on all platforms (little / big endian).
+
+|Branch      |Status   |
+|------------|---------|
+|master      | [![Build Status](https://travis-ci.org/Cyan4973/xxHash.svg?branch=master)](https://travis-ci.org/Cyan4973/xxHash?branch=master) |
+|dev         | [![Build Status](https://travis-ci.org/Cyan4973/xxHash.svg?branch=dev)](https://travis-ci.org/Cyan4973/xxHash?branch=dev) |
+
+
+
+Benchmarks
+-------------------------
+
+The benchmark uses SMHasher speed test, compiled with Visual 2010 on a Windows Seven 32-bit box.
+The reference system uses a Core 2 Duo @3GHz
+
+
+| Name          |   Speed            | Quality | Author            |
+|---------------|--------------------|:-------:|-------------------|
+| [xxHash]      | 5.4 GB/s           |   10    | Y.C.              |
+| MurmurHash 3a | 2.7 GB/s           |   10    | Austin Appleby    |
+| SBox          | 1.4 GB/s           |    9    | Bret Mulvey       |
+| Lookup3       | 1.2 GB/s           |    9    | Bob Jenkins       |
+| CityHash64    | 1.05 GB/s          |   10    | Pike & Alakuijala |
+| FNV           | 0.55 GB/s          |    5    | Fowler, Noll, Vo  |
+| CRC32         | 0.43 GB/s &dagger; |    9    |                   |
+| MD5-32        | 0.33 GB/s          |   10    | Ronald L.Rivest   |
+| SHA1-32       | 0.28 GB/s          |   10    |                   |
+
+[xxHash]: https://www.xxhash.com
+
+Note &dagger;: SMHasher's CRC32 implementation is known to be slow. Faster implementations exist.
+
+Q.Score is a measure of quality of the hash function.
+It depends on successfully passing SMHasher test set.
+10 is a perfect score.
+Algorithms with a score < 5 are not listed on this table.
+
+A more recent version, XXH64, has been created thanks to [Mathias Westerdahl](https://github.com/JCash),
+which offers superior speed and dispersion for 64-bit systems.
+Note however that 32-bit applications will still run faster using the 32-bit version.
+
+SMHasher speed test, compiled using GCC 4.8.2, on Linux Mint 64-bit.
+The reference system uses a Core i5-3340M @2.7GHz
+
+| Version    | Speed on 64-bit  | Speed on 32-bit  |
+|------------|------------------|------------------|
+| XXH64      | 13.8 GB/s        |  1.9 GB/s        |
+| XXH32      |  6.8 GB/s        |  6.0 GB/s        |
+
+This project also includes a command line utility, named `xxhsum`, offering similar features to `md5sum`,
+thanks to [Takayuki Matsuoka](https://github.com/t-mat)'s contributions.
+
+
+### License
+
+The library files `xxhash.c` and `xxhash.h` are BSD licensed.
+The utility `xxhsum` is GPL licensed.
+
+
+### New hash algorithms
+
+Starting with `v0.7.0`, the library includes a new algorithm named `XXH3`,
+which is able to generate 64 and 128-bit hashes.
+
+The new algorithm is much faster than its predecessors for both long and small inputs,
+which can be observed in the following graphs:
+
+![XXH3, bargraph](https://user-images.githubusercontent.com/750081/61976096-b3a35f00-af9f-11e9-8229-e0afc506c6ec.png)
+
+![XXH3, latency, random size](https://user-images.githubusercontent.com/750081/61976089-aedeab00-af9f-11e9-9239-e5375d6c080f.png)
+
+To access these new prototypes, one needs to unlock their declaration, using the build macro `XXH_STATIC_LINKING_ONLY`.
+
+The algorithm is currently in development, meaning its return values might still change in future versions.
+However, the API is stable, and can be used in production,
+typically for generation of ephemeral hashes (produced and consumed in same session).
+
+`XXH3` has now reached "release candidate" status.
+If everything remains fine, its format will be "frozen" and become final.
+After which, return values of `XXH3` and `XXH128` will no longer change in future versions.
+`XXH3`'s return values will be officially finalized upon reaching `v0.8.0`.
+
+
+### Build modifiers
+
+The following macros can be set at compilation time to modify libxxhash's behavior. They are generally disabled by default.
+
+- `XXH_INLINE_ALL`: Make all functions `inline`, with implementations being directly included within `xxhash.h`.
+                    Inlining functions is beneficial for speed on small keys.
+                    It's _extremely effective_ when key length is expressed as _a compile time constant_,
+                    with performance improvements observed in the +200% range .
+                    See [this article](https://fastcompression.blogspot.com/2018/03/xxhash-for-small-keys-impressive-power.html) for details.
+- `XXH_PRIVATE_API`: same outcome as `XXH_INLINE_ALL`. Still available for legacy support.
+                     The name underlines that `XXH_*` symbols will not be exported.
+- `XXH_NAMESPACE`: Prefixes all symbols with the value of `XXH_NAMESPACE`.
+                   This macro can only use compilable character set.
+                   Useful to evade symbol naming collisions,
+                   in case of multiple inclusions of xxHash's source code.
+                   Client applications still use the regular function names,
+                   as symbols are automatically translated through `xxhash.h`.
+- `XXH_FORCE_MEMORY_ACCESS`: The default method `0` uses a portable `memcpy()` notation.
+                             Method `1` uses a gcc-specific `packed` attribute, which can provide better performance for some targets.
+                             Method `2` forces unaligned reads, which is not standards compliant, but might sometimes be the only way to extract better read performance.
+                             Method `3` uses a byteshift operation, which is best for old compilers which don't inline `memcpy()` or big-endian systems without a byteswap instruction
+- `XXH_FORCE_ALIGN_CHECK`: Use a faster direct read path when input is aligned.
+                           This option can result in dramatic performance improvement when input to hash is aligned on 32 or 64-bit boundaries,
+                           when running on architectures unable to load memory from unaligned addresses, or suffering a performance penalty from it.
+                           It is (slightly) detrimental on platform with good unaligned memory access performance (same instruction for both aligned and unaligned accesses).
+                           This option is automatically disabled on `x86`, `x64` and `aarch64`, and enabled on all other platforms.
+- `XXH_VECTOR` : manually select a vector instruction set (default: auto-selected at compilation time). Available instruction sets are `XXH_SCALAR`, `XXH_SSE2`, `XXH_AVX2`, `XXH_AVX512`, `XXH_NEON` and `XXH_VSX`. Compiler may require additional flags to ensure proper support (for example, `gcc` on linux will require `-mavx2` for AVX2, and `-mavx512f` for AVX512).
+- `XXH_NO_PREFETCH` : disable prefetching. XXH3 only.
+- `XXH_PREFETCH_DIST` : select prefecting distance. XXH3 only.
+- `XXH_NO_INLINE_HINTS`: By default, xxHash uses `__attribute__((always_inline))` and `__forceinline` to improve performance at the cost of code size.
+                         Defining this macro to 1 will mark all internal functions as `static`, allowing the compiler to decide whether to inline a function or not.
+                         This is very useful when optimizing for smallest binary size,
+                         and is automatically defined when compiling with `-O0`, `-Os`, `-Oz`, or `-fno-inline` on GCC and Clang.
+                         This may also increase performance depending on compiler and architecture.
+- `XXH_REROLL`: Reduces the size of the generated code by not unrolling some loops.
+                Impact on performance may vary, depending on platform and algorithm.
+- `XXH_ACCEPT_NULL_INPUT_POINTER`: if set to `1`, when input is a `NULL` pointer,
+                                   xxHash'd result is the same as a zero-length input
+                                   (instead of a dereference segfault).
+                                   Adds one branch at the beginning of each hash.
+- `XXH_STATIC_LINKING_ONLY`: gives access to the state declaration for static allocation.
+                             Incompatible with dynamic linking, due to risks of ABI changes.
+- `XXH_NO_LONG_LONG`: removes compilation of algorithms relying on 64-bit types (XXH3 and XXH64). Only XXH32 will be compiled.
+                      Useful for targets (architectures and compilers) without 64-bit support.
+- `XXH_IMPORT`: MSVC specific: should only be defined for dynamic linking, as it prevents linkage errors.
+- `XXH_CPU_LITTLE_ENDIAN`: By default, endianess is determined by a runtime test resolved at compile time.
+                           If, for some reason, the compiler cannot simplify the runtime test, it can cost performance.
+                           It's possible to skip auto-detection and simply state that the architecture is little-endian by setting this macro to 1.
+                           Setting it to 0 states big-endian.
+
+For the Command Line Interface `xxhsum`, the following environment variables can also be set :
+- `DISPATCH=1` : use `xxh_x86dispatch.c`, to automatically select between `scalar`, `sse2`, `avx2` or `avx512` instruction set at runtime, depending on local host. This option is only valid for `x86`/`x64` systems.
+
+
+### Building xxHash - Using vcpkg
+
+You can download and install xxHash using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
+
+    git clone https://github.com/Microsoft/vcpkg.git
+    cd vcpkg
+    ./bootstrap-vcpkg.sh
+    ./vcpkg integrate install
+    ./vcpkg install xxhash
+
+The xxHash port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
+
+
+### Example
+
+Calling xxhash 64-bit variant from a C program:
+
+```C
+#include "xxhash.h"
+
+    (...)
+    XXH64_hash_t hash = XXH64(buffer, size, seed);
+}
+```
+
+Using streaming variant is more involved, but makes it possible to provide data incrementally:
+```C
+#include "stdlib.h"   /* abort() */
+#include "xxhash.h"
+
+
+XXH64_hash_t calcul_hash_streaming(FileHandler fh)
+{
+    /* create a hash state */
+    XXH64_state_t* const state = XXH64_createState();
+    if (state==NULL) abort();
+
+    size_t const bufferSize = SOME_SIZE;
+    void* const buffer = malloc(bufferSize);
+    if (buffer==NULL) abort();
+
+    /* Initialize state with selected seed */
+    XXH64_hash_t const seed = 0;   /* or any other value */
+    if (XXH64_reset(state, seed) == XXH_ERROR) abort();
+
+    /* Feed the state with input data, any size, any number of times */
+    (...)
+    while ( /* any condition */ ) {
+        size_t const length = get_more_data(buffer, bufferSize, fh);
+        if (XXH64_update(state, buffer, length) == XXH_ERROR) abort();
+        (...)
+    }
+    (...)
+
+    /* Get the hash */
+    XXH64_hash_t const hash = XXH64_digest(state);
+
+    /* State can be re-used; in this example, it is simply freed  */
+    free(buffer);
+    XXH64_freeState(state);
+
+    return hash;
+}
+```
+
+
+### Other programming languages
+
+Aside from the C reference version,
+xxHash is also available in many different programming languages,
+thanks to many great contributors.
+They are [listed here](https://www.xxhash.com/#other-languages).
+
+
+### Branch Policy
+
+> - The "master" branch is considered stable, at all times.
+> - The "dev" branch is the one where all contributions must be merged
+    before being promoted to master.
+>   + If you plan to propose a patch, please commit into the "dev" branch,
+      or its own feature branch.
+      Direct commit to "master" are not permitted.