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MurmurHash3.cpp (8458B)

---

//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.

// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.

#include "MurmurHash3.h"

namespace {

//-----------------------------------------------------------------------------
// Platform-specific functions and macros

// Microsoft Visual Studio

#if defined(_MSC_VER)

#  define FORCE_INLINE __forceinline

#  define ROTL32(x, y) _rotl(x, y)
#  define ROTL64(x, y) _rotl64(x, y)

#  define BIG_CONSTANT(x) (x)

// Other compilers

#else  // defined(_MSC_VER)

// We can't do always_inline, becasue -Werror -Wattribute will trigger
// a "might not be able to inline" warning.
// #define	FORCE_INLINE __attribute__((always_inline))
#  define FORCE_INLINE inline

inline uint32_t rotl32(uint32_t x, int8_t r) {
 return (x << r) | (x >> (32 - r));
}

inline uint64_t rotl64(uint64_t x, int8_t r) {
 return (x << r) | (x >> (64 - r));
}

#  define ROTL32(x, y) rotl32(x, y)
#  define ROTL64(x, y) rotl64(x, y)

#  define BIG_CONSTANT(x) (x##LLU)

#endif  // !defined(_MSC_VER)

//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here

FORCE_INLINE uint32_t getblock(const uint32_t* p, int i) { return p[i]; }

FORCE_INLINE uint64_t getblock(const uint64_t* p, int i) { return p[i]; }

//-----------------------------------------------------------------------------
// Finalization mix - force all bits of a hash block to avalanche

FORCE_INLINE uint32_t fmix(uint32_t h) {
 h ^= h >> 16;
 h *= 0x85ebca6b;
 h ^= h >> 13;
 h *= 0xc2b2ae35;
 h ^= h >> 16;

 return h;
}

//----------

FORCE_INLINE uint64_t fmix(uint64_t k) {
 k ^= k >> 33;
 k *= BIG_CONSTANT(0xff51afd7ed558ccd);
 k ^= k >> 33;
 k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
 k ^= k >> 33;

 return k;
}

}  // unnamed namespace

//-----------------------------------------------------------------------------

void MurmurHash3_x86_32(const void* key, int len, uint32_t seed, void* out) {
 const uint8_t* data = (const uint8_t*)key;
 const int nblocks = len / 4;

 uint32_t h1 = seed;

 const uint32_t c1 = 0xcc9e2d51;
 const uint32_t c2 = 0x1b873593;

 //----------
 // body

 const uint32_t* blocks = (const uint32_t*)(data + nblocks * 4);

 for (int i = -nblocks; i; i++) {
   uint32_t k1 = getblock(blocks, i);

   k1 *= c1;
   k1 = ROTL32(k1, 15);
   k1 *= c2;

   h1 ^= k1;
   h1 = ROTL32(h1, 13);
   h1 = h1 * 5 + 0xe6546b64;
 }

 //----------
 // tail

 const uint8_t* tail = (const uint8_t*)(data + nblocks * 4);

 uint32_t k1 = 0;

 switch (len & 3) {
   case 3:
     k1 ^= tail[2] << 16;
   case 2:
     k1 ^= tail[1] << 8;
   case 1:
     k1 ^= tail[0];
     k1 *= c1;
     k1 = ROTL32(k1, 15);
     k1 *= c2;
     h1 ^= k1;
 }

 //----------
 // finalization

 h1 ^= len;

 h1 = fmix(h1);

 *(uint32_t*)out = h1;
}

//-----------------------------------------------------------------------------

void MurmurHash3_x86_128(const void* key, const int len, uint32_t seed,
                        void* out) {
 const uint8_t* data = (const uint8_t*)key;
 const int nblocks = len / 16;

 uint32_t h1 = seed;
 uint32_t h2 = seed;
 uint32_t h3 = seed;
 uint32_t h4 = seed;

 const uint32_t c1 = 0x239b961b;
 const uint32_t c2 = 0xab0e9789;
 const uint32_t c3 = 0x38b34ae5;
 const uint32_t c4 = 0xa1e38b93;

 //----------
 // body

 const uint32_t* blocks = (const uint32_t*)(data + nblocks * 16);

 for (int i = -nblocks; i; i++) {
   uint32_t k1 = getblock(blocks, i * 4 + 0);
   uint32_t k2 = getblock(blocks, i * 4 + 1);
   uint32_t k3 = getblock(blocks, i * 4 + 2);
   uint32_t k4 = getblock(blocks, i * 4 + 3);

   k1 *= c1;
   k1 = ROTL32(k1, 15);
   k1 *= c2;
   h1 ^= k1;

   h1 = ROTL32(h1, 19);
   h1 += h2;
   h1 = h1 * 5 + 0x561ccd1b;

   k2 *= c2;
   k2 = ROTL32(k2, 16);
   k2 *= c3;
   h2 ^= k2;

   h2 = ROTL32(h2, 17);
   h2 += h3;
   h2 = h2 * 5 + 0x0bcaa747;

   k3 *= c3;
   k3 = ROTL32(k3, 17);
   k3 *= c4;
   h3 ^= k3;

   h3 = ROTL32(h3, 15);
   h3 += h4;
   h3 = h3 * 5 + 0x96cd1c35;

   k4 *= c4;
   k4 = ROTL32(k4, 18);
   k4 *= c1;
   h4 ^= k4;

   h4 = ROTL32(h4, 13);
   h4 += h1;
   h4 = h4 * 5 + 0x32ac3b17;
 }

 //----------
 // tail

 const uint8_t* tail = (const uint8_t*)(data + nblocks * 16);

 uint32_t k1 = 0;
 uint32_t k2 = 0;
 uint32_t k3 = 0;
 uint32_t k4 = 0;

 switch (len & 15) {
   case 15:
     k4 ^= tail[14] << 16;
   case 14:
     k4 ^= tail[13] << 8;
   case 13:
     k4 ^= tail[12] << 0;
     k4 *= c4;
     k4 = ROTL32(k4, 18);
     k4 *= c1;
     h4 ^= k4;

   case 12:
     k3 ^= tail[11] << 24;
   case 11:
     k3 ^= tail[10] << 16;
   case 10:
     k3 ^= tail[9] << 8;
   case 9:
     k3 ^= tail[8] << 0;
     k3 *= c3;
     k3 = ROTL32(k3, 17);
     k3 *= c4;
     h3 ^= k3;

   case 8:
     k2 ^= tail[7] << 24;
   case 7:
     k2 ^= tail[6] << 16;
   case 6:
     k2 ^= tail[5] << 8;
   case 5:
     k2 ^= tail[4] << 0;
     k2 *= c2;
     k2 = ROTL32(k2, 16);
     k2 *= c3;
     h2 ^= k2;

   case 4:
     k1 ^= tail[3] << 24;
   case 3:
     k1 ^= tail[2] << 16;
   case 2:
     k1 ^= tail[1] << 8;
   case 1:
     k1 ^= tail[0] << 0;
     k1 *= c1;
     k1 = ROTL32(k1, 15);
     k1 *= c2;
     h1 ^= k1;
 }

 //----------
 // finalization

 h1 ^= len;
 h2 ^= len;
 h3 ^= len;
 h4 ^= len;

 h1 += h2;
 h1 += h3;
 h1 += h4;
 h2 += h1;
 h3 += h1;
 h4 += h1;

 h1 = fmix(h1);
 h2 = fmix(h2);
 h3 = fmix(h3);
 h4 = fmix(h4);

 h1 += h2;
 h1 += h3;
 h1 += h4;
 h2 += h1;
 h3 += h1;
 h4 += h1;

 ((uint32_t*)out)[0] = h1;
 ((uint32_t*)out)[1] = h2;
 ((uint32_t*)out)[2] = h3;
 ((uint32_t*)out)[3] = h4;
}

//-----------------------------------------------------------------------------

void MurmurHash3_x64_128(const void* key, const int len, const uint32_t seed,
                        void* out) {
 const uint8_t* data = (const uint8_t*)key;
 const int nblocks = len / 16;

 uint64_t h1 = seed;
 uint64_t h2 = seed;

 const uint64_t c1 = BIG_CONSTANT(0x87c37b91114253d5);
 const uint64_t c2 = BIG_CONSTANT(0x4cf5ad432745937f);

 //----------
 // body

 const uint64_t* blocks = (const uint64_t*)(data);

 for (int i = 0; i < nblocks; i++) {
   uint64_t k1 = getblock(blocks, i * 2 + 0);
   uint64_t k2 = getblock(blocks, i * 2 + 1);

   k1 *= c1;
   k1 = ROTL64(k1, 31);
   k1 *= c2;
   h1 ^= k1;

   h1 = ROTL64(h1, 27);
   h1 += h2;
   h1 = h1 * 5 + 0x52dce729;

   k2 *= c2;
   k2 = ROTL64(k2, 33);
   k2 *= c1;
   h2 ^= k2;

   h2 = ROTL64(h2, 31);
   h2 += h1;
   h2 = h2 * 5 + 0x38495ab5;
 }

 //----------
 // tail

 const uint8_t* tail = (const uint8_t*)(data + nblocks * 16);

 uint64_t k1 = 0;
 uint64_t k2 = 0;

 switch (len & 15) {
   case 15:
     k2 ^= uint64_t(tail[14]) << 48;
   case 14:
     k2 ^= uint64_t(tail[13]) << 40;
   case 13:
     k2 ^= uint64_t(tail[12]) << 32;
   case 12:
     k2 ^= uint64_t(tail[11]) << 24;
   case 11:
     k2 ^= uint64_t(tail[10]) << 16;
   case 10:
     k2 ^= uint64_t(tail[9]) << 8;
   case 9:
     k2 ^= uint64_t(tail[8]) << 0;
     k2 *= c2;
     k2 = ROTL64(k2, 33);
     k2 *= c1;
     h2 ^= k2;

   case 8:
     k1 ^= uint64_t(tail[7]) << 56;
   case 7:
     k1 ^= uint64_t(tail[6]) << 48;
   case 6:
     k1 ^= uint64_t(tail[5]) << 40;
   case 5:
     k1 ^= uint64_t(tail[4]) << 32;
   case 4:
     k1 ^= uint64_t(tail[3]) << 24;
   case 3:
     k1 ^= uint64_t(tail[2]) << 16;
   case 2:
     k1 ^= uint64_t(tail[1]) << 8;
   case 1:
     k1 ^= uint64_t(tail[0]) << 0;
     k1 *= c1;
     k1 = ROTL64(k1, 31);
     k1 *= c2;
     h1 ^= k1;
 }

 //----------
 // finalization

 h1 ^= len;
 h2 ^= len;

 h1 += h2;
 h2 += h1;

 h1 = fmix(h1);
 h2 = fmix(h2);

 h1 += h2;
 h2 += h1;

 ((uint64_t*)out)[0] = h1;
 ((uint64_t*)out)[1] = h2;
}

//-----------------------------------------------------------------------------