//-----------------------------------------------------------------------------
// 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"

//-----------------------------------------------------------------------------
#define FORCE_INLINE inline __attribute__((always_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)

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

FORCE_INLINE uint32_t
getblock32(const uint32_t *p, int i)
{
  return p[i];
}

FORCE_INLINE uint64_t
getblock64(const uint64_t *p, int i)
{
  return p[i];
}

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

FORCE_INLINE uint32_t
fmix32(uint32_t h)
{
  h ^= h >> 16;
  h *= 0x85ebca6b;
  h ^= h >> 13;
  h *= 0xc2b2ae35;
  h ^= h >> 16;

  return h;
}

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

FORCE_INLINE uint64_t
fmix64(uint64_t k)
{
  k ^= k >> 33;
  k *= BIG_CONSTANT(0xff51afd7ed558ccd);
  k ^= k >> 33;
  k *= BIG_CONSTANT(0xc4ceb9fe1a85ec53);
  k ^= k >> 33;

  return k;
}

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

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 = getblock32(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;
  // fallthrough

  case 2:
    k1 ^= tail[1] << 8;
  // fallthrough

  case 1:
    k1 ^= tail[0];
    k1 *= c1;
    k1 = ROTL32(k1, 15);
    k1 *= c2;
    h1 ^= k1;
  };

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

  h1 ^= len;

  h1 = fmix32(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 = getblock32(blocks, i * 4 + 0);
    uint32_t k2 = getblock32(blocks, i * 4 + 1);
    uint32_t k3 = getblock32(blocks, i * 4 + 2);
    uint32_t k4 = getblock32(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;
  // fallthrough

  case 14:
    k4 ^= tail[13] << 8;
  // fallthrough

  case 13:
    k4 ^= tail[12] << 0;
    k4 *= c4;
    k4 = ROTL32(k4, 18);
    k4 *= c1;
    h4 ^= k4;
  // fallthrough

  case 12:
    k3 ^= tail[11] << 24;
  // fallthrough

  case 11:
    k3 ^= tail[10] << 16;
  // fallthrough

  case 10:
    k3 ^= tail[9] << 8;
  // fallthrough

  case 9:
    k3 ^= tail[8] << 0;
    k3 *= c3;
    k3 = ROTL32(k3, 17);
    k3 *= c4;
    h3 ^= k3;
  // fallthrough

  case 8:
    k2 ^= tail[7] << 24;
  // fallthrough

  case 7:
    k2 ^= tail[6] << 16;
  // fallthrough

  case 6:
    k2 ^= tail[5] << 8;
  // fallthrough

  case 5:
    k2 ^= tail[4] << 0;
    k2 *= c2;
    k2 = ROTL32(k2, 16);
    k2 *= c3;
    h2 ^= k2;
  // fallthrough

  case 4:
    k1 ^= tail[3] << 24;
  // fallthrough

  case 3:
    k1 ^= tail[2] << 16;
  // fallthrough

  case 2:
    k1 ^= tail[1] << 8;
  // fallthrough

  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 = fmix32(h1);
  h2 = fmix32(h2);
  h3 = fmix32(h3);
  h4 = fmix32(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;
}

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