simdhwyhash is an implementation of HighwayHash that uses the Google Highway SIMD library.

simdhwyhash requires a C++17 compiler capable of compiling Google Highway (such as GCC 7 or later or Clang 6 or later) and cmake to build.

simdhwyhash also requires that git is installed to download the Google Highway dependency if SIMDHWYHASH_SYSTEM_HIGHWAY is set to OFF.

To build simdhwyhash as a shared or static library (depending on BUILD_SHARED_LIBS), the standard CMake workflow can be used:

mkdir -p build && cd build
cmake ..
make -j && make test

simdhwyhash exposes a C API to allow simdhwyhash to be used from languages other than C++.

• void SimdHwyHash_Reset(SimdHwyHashState* state, const uint64_t* key) - initializes state using key (which is an array of 4 uint64_t values)

• void SimdHwyHash_Update(SimdHwyHashState* state, const void* ptr, size_t byte_len) - updates state with byte_len bytes from ptr

  state must be initialized using SimdHwyHash_Reset prior to the first call to SimdHwyHash_Update.

  If state is going to be updated with additional data, byte_len should be a multiple of 32. Otherwise, if this is the final SimdHwyHash_Update step, byte_len should be equal to the length of the remaining data.

• uint64_t SimdHwyHash_Finalize64(SimdHwyHashState* state) - returns the 64-bit hash of the data

  state must be initialized using SimdHwyHash_Reset, followed by zero or more calls to SimdHwyHash_Update, prior to calling SimdHwyHash_Finalize64.

• void SimdHwyHash_Finalize128(SimdHwyHashState* state, uint64_t* hash) - returns the 128-bit hash of the data in hash[0] and hash[1]

  state must be initialized using SimdHwyHash_Reset, followed by zero or more calls to SimdHwyHash_Update, prior to calling SimdHwyHash_Finalize128.

• void SimdHwyHash_Finalize256(SimdHwyHashState* state, uint64_t* hash) - returns the 256-bit hash of the data in hash[0], hash[1], hash[2], and hash[3]

  state must be initialized using SimdHwyHash_Reset, followed by zero or more calls to SimdHwyHash_Update, prior to calling SimdHwyHash_Finalize256.

• uint64_t SimdHwyHash_Hash64(const void* ptr, size_t byte_len, const uint64_t* key) - returns the 64-bit hash of byte_len bytes of data pointed to by ptr, hashed using key (which is an array of 4 uint64_t values)

  SimdHwyHash_Hash64(ptr, byte_len, key) is equivalent to the following:

  SimdHwyHashState state;
  SimdHwyHash_Reset(&state, key);
  SimdHwyHash_Update(&state, ptr, byte_len);
  const uint64_t hash64 = SimdHwyHash_Finalize64(&state);
  

• void SimdHwyHash_Hash128(const void* ptr, size_t byte_len, const uint64_t* key, uint64_t* hash) - returns the 128-bit hash of byte_len bytes of data pointed to by ptr in hash[0] and hash[1], hashed using key (which is an array of 4 uint64_t values)

  SimdHwyHash_Hash128(ptr, byte_len, key, hash) is equivalent to the following:

  SimdHwyHashState state;
  SimdHwyHash_Reset(&state, key);
  SimdHwyHash_Update(&state, ptr, byte_len);
  SimdHwyHash_Finalize128(&state, hash);
  

• void SimdHwyHash_Hash256(const void* ptr, size_t byte_len, const uint64_t* key, uint64_t* hash) - returns the 256-bit hash of byte_len bytes of data pointed to by ptr in hash[0], hash[1], hash[2], and hash[3], hashed using key (which is an array of 4 uint64_t values)

  SimdHwyHash_Hash256(ptr, byte_len, key, hash) is equivalent to the following:

  SimdHwyHashState state;
  SimdHwyHash_Reset(&state, key);
  SimdHwyHash_Update(&state, ptr, byte_len);
  SimdHwyHash_Finalize256(&state, hash);
  

• BUILD_SHARED_LIBS (defaults to ON) - set to OFF to build simdhwyhash as a static library. simdhwyhash is configured to be built as a shared library if BUILD_SHARED_LIBS is ON and SIMDHWYHASH_FORCE_STATIC_LIBS is OFF.

• HWY_CMAKE_ARM7 (defaults to OFF) - set to enable Armv7 Highway compilation flags

• HWY_CMAKE_SSE2 (defaults to OFF) - set to enable SSE2 as the baseline on 32-bit x86

• HWY_CMAKE_RVV (defaults to ON) - set to enable the RISC-V "V" extension if compiling on RISC-V

• SIMDHWYHASH_ENABLE_INSTALL (defaults to ON) - set to OFF to disable the installation of the simdhwyhash library

• SIMDHWYHASH_ENABLE_TESTS (defaults to ON) - set to OFF to disable the simdhwyhash unit tests

• SIMDHWYHASH_FORCE_STATIC_LIBS (defaults to OFF) - set to ON to build simdhwyhash as a static library, regardless of whether BUILD_SHARED_LIBS is set to ON or OFF.

• SIMDHWYHASH_HWY_CXX_FLAGS - Additional C++ compiler flags used to compile the simdhwyhash library and Google Highway (if the system included Google Highway library is not used)

• SIMDHWYHASH_SYSTEM_HIGHWAY (defaults to OFF) - set to ON to use the system included Google Highway library

• SIMDHWYHASH_SYSTEM_GTEST (defaults to OFF) - set to ON to use the system included Google Test library

• SIMDHWYHASH_WARNINGS_ARE_ERRORS (defaults to OFF) - set to ON to treat compiler warnings as errors