// 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.

// Originally taken from: https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp

#include "hash.h"

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

// Microsoft Visual Studio

#if defined(_MSC_VER)

#define FORCE_INLINE    __forceinline

#include <stdlib.h>

#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)

#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)

#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 getblock32_aligned(const uint32_t* p, int i) {
    return p[i];
}

FORCE_INLINE uint32_t getblock32_unaligned(const uint32_t* p, int i) {
    auto b = reinterpret_cast<const uint8_t*>(p);
    return (static_cast<uint32_t>(b[0]) << 24)
         | (static_cast<uint32_t>(b[1]) << 16)
         | (static_cast<uint32_t>(b[2]) << 8)
         |  static_cast<uint32_t>(b[3]);
}

FORCE_INLINE uint64_t getblock64_aligned(const uint64_t * p, int i) {
    return p[i];
}

FORCE_INLINE uint64_t getblock64_unaligned(const uint64_t * p, int i) {
    auto b = reinterpret_cast<const uint8_t*>(p);
    return (static_cast<uint64_t>(b[0]) << 56)
         | (static_cast<uint64_t>(b[1]) << 48)
         | (static_cast<uint64_t>(b[2]) << 40)
         | (static_cast<uint64_t>(b[3]) << 32)
         | (static_cast<uint64_t>(b[4]) << 24)
         | (static_cast<uint64_t>(b[5]) << 16)
         | (static_cast<uint64_t>(b[6]) << 8)
         |  static_cast<uint64_t>(b[7]);
}

//-----------------------------------------------------------------------------
// 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;
}

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

template<uint32_t (*getblock)(const uint32_t * p, int i)>
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 = fmix32(h1);

    *(uint32_t*)out = h1;
}

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

template<uint32_t (*getblock)(const uint32_t * p, int i)>
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 = 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;
}

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

template<uint64_t (*getblock)(const uint64_t * p, int i)>
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 = fmix64(h1);
    h2 = fmix64(h2);

    h1 += h2;
    h2 += h1;

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

void MurmurHash3_x86_32(const void * key, int len, uint32_t seed, void * out) {
    if ((reinterpret_cast<uintptr_t>(key) & 0x3) == 0) {
        MurmurHash3_x86_32_<getblock32_aligned>(key, len, seed, out);
    } else {
        MurmurHash3_x86_32_<getblock32_unaligned>(key, len, seed, out);
    }
}

void MurmurHash3_x86_128(const void * key, const int len, uint32_t seed, void * out) {
    if ((reinterpret_cast<uintptr_t>(key) & 0x3) == 0) {
        MurmurHash3_x86_128_<getblock32_aligned>(key, len, seed, out);
    } else {
        MurmurHash3_x86_128_<getblock32_unaligned>(key, len, seed, out);
    }
}

void MurmurHash3_x64_128(const void * key, const int len, uint32_t seed, void * out) {
    if ((reinterpret_cast<uintptr_t>(key) & 0x7) == 0) {
        MurmurHash3_x64_128_<getblock64_aligned>(key, len, seed, out);
    } else {
        MurmurHash3_x64_128_<getblock64_unaligned>(key, len, seed, out);
    }
}