#include "stdint.h"

uint32_t murmurhash3_32_x86(const unsigned char* key, int len, int32_t seed);

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

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

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

    return h;
}

uint32_t murmurhash3_32_x86(const unsigned char* key, int len, int32_t seed) {
    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);

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

    return h1;
}
