//
// Created by Aaron Gill-Braun on 2020-10-30.
//

// A port of the Murmur3 hash function. Original implementation
// can be found here: https://github.com/aappleby/smhasher

#include "murmur3.h"

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

static 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

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

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

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

always_inline uint32_t fmix32(uint32_t h) {
  h ^= h >> 16;
  h *= 0x85EBCA6B;
  h ^= h >> 13;
  h *= 0xC2B2AE35;
  h ^= h >> 16;

  return h;
}

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

always_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 murmur_hash_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;
    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 = fmix32(h1);

  *(uint32_t *) out = h1;
}

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

void murmur_hash_x86_128(const void *key, 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;
    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 = 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;
}

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

void murmur_hash_x64_128(const void *key, int len, 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 = getblock64(blocks, i * 2 + 0);
    uint64_t k2 = getblock64(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 = fmix64(h1);
  h2 = fmix64(h2);

  h1 += h2;
  h2 += h1;

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

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