// metrohash64.cpp
//
// Copyright 2015-2018 J. Andrew Rogers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "platform.h"
#include "metrohash64.h"

#include <cstring>

const char * MetroHash64::test_string = "012345678901234567890123456789012345678901234567890123456789012";

const uint8_t MetroHash64::test_seed_0[8] =   { 0x6B, 0x75, 0x3D, 0xAE, 0x06, 0x70, 0x4B, 0xAD };
const uint8_t MetroHash64::test_seed_1[8] =   { 0x3B, 0x0D, 0x48, 0x1C, 0xF4, 0xB9, 0xB8, 0xDF };



MetroHash64::MetroHash64(const uint64_t seed)
{
    Initialize(seed);
}


void MetroHash64::Initialize(const uint64_t seed)
{
    vseed = (static_cast<uint64_t>(seed) + k2) * k0;

    // initialize internal hash registers
    state.v[0] = vseed;
    state.v[1] = vseed;
    state.v[2] = vseed;
    state.v[3] = vseed;

    // initialize total length of input
    bytes = 0;
}


void MetroHash64::Update(const uint8_t * const buffer, const uint64_t length)
{
    const uint8_t * ptr = reinterpret_cast<const uint8_t*>(buffer);
    const uint8_t * const end = ptr + length;

    // input buffer may be partially filled
    if (bytes % 32)
    {
        uint64_t fill = 32 - (bytes % 32);
        if (fill > length)
            fill = length;

        memcpy(input.b + (bytes % 32), ptr, static_cast<size_t>(fill));
        ptr   += fill;
        bytes += fill;
        
        // input buffer is still partially filled
        if ((bytes % 32) != 0) return;

        // process full input buffer
        state.v[0] += read_u64(&input.b[ 0]) * k0; state.v[0] = rotate_right(state.v[0],29) + state.v[2];
        state.v[1] += read_u64(&input.b[ 8]) * k1; state.v[1] = rotate_right(state.v[1],29) + state.v[3];
        state.v[2] += read_u64(&input.b[16]) * k2; state.v[2] = rotate_right(state.v[2],29) + state.v[0];
        state.v[3] += read_u64(&input.b[24]) * k3; state.v[3] = rotate_right(state.v[3],29) + state.v[1];
    }
    
    // bulk update
    bytes += static_cast<uint64_t>(end - ptr);
    while (ptr <= (end - 32))
    {
        // process directly from the source, bypassing the input buffer
        state.v[0] += read_u64(ptr) * k0; ptr += 8; state.v[0] = rotate_right(state.v[0],29) + state.v[2];
        state.v[1] += read_u64(ptr) * k1; ptr += 8; state.v[1] = rotate_right(state.v[1],29) + state.v[3];
        state.v[2] += read_u64(ptr) * k2; ptr += 8; state.v[2] = rotate_right(state.v[2],29) + state.v[0];
        state.v[3] += read_u64(ptr) * k3; ptr += 8; state.v[3] = rotate_right(state.v[3],29) + state.v[1];
    }
    
    // store remaining bytes in input buffer
    if (ptr < end)
        memcpy(input.b, ptr, static_cast<size_t>(end - ptr));
}


void MetroHash64::Finalize(uint8_t * const hash)
{
    // finalize bulk loop, if used
    if (bytes >= 32)
    {
        state.v[2] ^= rotate_right(((state.v[0] + state.v[3]) * k0) + state.v[1], 37) * k1;
        state.v[3] ^= rotate_right(((state.v[1] + state.v[2]) * k1) + state.v[0], 37) * k0;
        state.v[0] ^= rotate_right(((state.v[0] + state.v[2]) * k0) + state.v[3], 37) * k1;
        state.v[1] ^= rotate_right(((state.v[1] + state.v[3]) * k1) + state.v[2], 37) * k0;

        state.v[0] = vseed + (state.v[0] ^ state.v[1]);
    }
    
    // process any bytes remaining in the input buffer
    const uint8_t * ptr = reinterpret_cast<const uint8_t*>(input.b);
    const uint8_t * const end = ptr + (bytes % 32);
    
    if ((end - ptr) >= 16)
    {
        state.v[1]  = state.v[0] + (read_u64(ptr) * k2); ptr += 8; state.v[1] = rotate_right(state.v[1],29) * k3;
        state.v[2]  = state.v[0] + (read_u64(ptr) * k2); ptr += 8; state.v[2] = rotate_right(state.v[2],29) * k3;
        state.v[1] ^= rotate_right(state.v[1] * k0, 21) + state.v[2];
        state.v[2] ^= rotate_right(state.v[2] * k3, 21) + state.v[1];
        state.v[0] += state.v[2];
    }

    if ((end - ptr) >= 8)
    {
        state.v[0] += read_u64(ptr) * k3; ptr += 8;
        state.v[0] ^= rotate_right(state.v[0], 55) * k1;
    }

    if ((end - ptr) >= 4)
    {
        state.v[0] += read_u32(ptr) * k3; ptr += 4;
        state.v[0] ^= rotate_right(state.v[0], 26) * k1;
    }

    if ((end - ptr) >= 2)
    {
        state.v[0] += read_u16(ptr) * k3; ptr += 2;
        state.v[0] ^= rotate_right(state.v[0], 48) * k1;
    }

    if ((end - ptr) >= 1)
    {
        state.v[0] += read_u8 (ptr) * k3;
        state.v[0] ^= rotate_right(state.v[0], 37) * k1;
    }
    
    state.v[0] ^= rotate_right(state.v[0], 28);
    state.v[0] *= k0;
    state.v[0] ^= rotate_right(state.v[0], 29);

    bytes = 0;

    // do any endian conversion here

    memcpy(hash, state.v, 8);
}


void MetroHash64::Hash(const uint8_t * buffer, const uint64_t length, uint8_t * const hash, const uint64_t seed)
{
    const uint8_t * ptr = reinterpret_cast<const uint8_t*>(buffer);
    const uint8_t * const end = ptr + length;

    uint64_t h = (static_cast<uint64_t>(seed) + k2) * k0;

    if (length >= 32)
    {
        uint64_t v[4];
        v[0] = h;
        v[1] = h;
        v[2] = h;
        v[3] = h;

        do
        {
            v[0] += read_u64(ptr) * k0; ptr += 8; v[0] = rotate_right(v[0],29) + v[2];
            v[1] += read_u64(ptr) * k1; ptr += 8; v[1] = rotate_right(v[1],29) + v[3];
            v[2] += read_u64(ptr) * k2; ptr += 8; v[2] = rotate_right(v[2],29) + v[0];
            v[3] += read_u64(ptr) * k3; ptr += 8; v[3] = rotate_right(v[3],29) + v[1];
        }
        while (ptr <= (end - 32));

        v[2] ^= rotate_right(((v[0] + v[3]) * k0) + v[1], 37) * k1;
        v[3] ^= rotate_right(((v[1] + v[2]) * k1) + v[0], 37) * k0;
        v[0] ^= rotate_right(((v[0] + v[2]) * k0) + v[3], 37) * k1;
        v[1] ^= rotate_right(((v[1] + v[3]) * k1) + v[2], 37) * k0;
        h += v[0] ^ v[1];
    }

    if ((end - ptr) >= 16)
    {
        uint64_t v0 = h + (read_u64(ptr) * k2); ptr += 8; v0 = rotate_right(v0,29) * k3;
        uint64_t v1 = h + (read_u64(ptr) * k2); ptr += 8; v1 = rotate_right(v1,29) * k3;
        v0 ^= rotate_right(v0 * k0, 21) + v1;
        v1 ^= rotate_right(v1 * k3, 21) + v0;
        h += v1;
    }

    if ((end - ptr) >= 8)
    {
        h += read_u64(ptr) * k3; ptr += 8;
        h ^= rotate_right(h, 55) * k1;
    }

    if ((end - ptr) >= 4)
    {
        h += read_u32(ptr) * k3; ptr += 4;
        h ^= rotate_right(h, 26) * k1;
    }

    if ((end - ptr) >= 2)
    {
        h += read_u16(ptr) * k3; ptr += 2;
        h ^= rotate_right(h, 48) * k1;
    }

    if ((end - ptr) >= 1)
    {
        h += read_u8 (ptr) * k3;
        h ^= rotate_right(h, 37) * k1;
    }

    h ^= rotate_right(h, 28);
    h *= k0;
    h ^= rotate_right(h, 29);

    memcpy(hash, &h, 8);
}


bool MetroHash64::ImplementationVerified()
{
    uint8_t hash[8];
    const uint8_t * key = reinterpret_cast<const uint8_t *>(MetroHash64::test_string);

    // verify one-shot implementation
    MetroHash64::Hash(key, strlen(MetroHash64::test_string), hash, 0);
    if (memcmp(hash, MetroHash64::test_seed_0, 8) != 0) return false;

    MetroHash64::Hash(key, strlen(MetroHash64::test_string), hash, 1);
    if (memcmp(hash, MetroHash64::test_seed_1, 8) != 0) return false;

    // verify incremental implementation
    MetroHash64 metro;
    
    metro.Initialize(0);
    metro.Update(reinterpret_cast<const uint8_t *>(MetroHash64::test_string), strlen(MetroHash64::test_string));
    metro.Finalize(hash);
    if (memcmp(hash, MetroHash64::test_seed_0, 8) != 0) return false;

    metro.Initialize(1);
    metro.Update(reinterpret_cast<const uint8_t *>(MetroHash64::test_string), strlen(MetroHash64::test_string));
    metro.Finalize(hash);
    if (memcmp(hash, MetroHash64::test_seed_1, 8) != 0) return false;

    return true;
}


void metrohash64_1(const uint8_t * key, uint64_t len, uint32_t seed, uint8_t * out)
{
    static const uint64_t k0 = 0xC83A91E1;
    static const uint64_t k1 = 0x8648DBDB;
    static const uint64_t k2 = 0x7BDEC03B;
    static const uint64_t k3 = 0x2F5870A5;

    const uint8_t * ptr = reinterpret_cast<const uint8_t*>(key);
    const uint8_t * const end = ptr + len;
    
    uint64_t hash = ((static_cast<uint64_t>(seed) + k2) * k0) + len;
    
    if (len >= 32)
    {
        uint64_t v[4];
        v[0] = hash;
        v[1] = hash;
        v[2] = hash;
        v[3] = hash;
        
        do
        {
            v[0] += read_u64(ptr) * k0; ptr += 8; v[0] = rotate_right(v[0],29) + v[2];
            v[1] += read_u64(ptr) * k1; ptr += 8; v[1] = rotate_right(v[1],29) + v[3];
            v[2] += read_u64(ptr) * k2; ptr += 8; v[2] = rotate_right(v[2],29) + v[0];
            v[3] += read_u64(ptr) * k3; ptr += 8; v[3] = rotate_right(v[3],29) + v[1];
        }
        while (ptr <= (end - 32));

        v[2] ^= rotate_right(((v[0] + v[3]) * k0) + v[1], 33) * k1;
        v[3] ^= rotate_right(((v[1] + v[2]) * k1) + v[0], 33) * k0;
        v[0] ^= rotate_right(((v[0] + v[2]) * k0) + v[3], 33) * k1;
        v[1] ^= rotate_right(((v[1] + v[3]) * k1) + v[2], 33) * k0;
        hash += v[0] ^ v[1];
    }
    
    if ((end - ptr) >= 16)
    {
        uint64_t v0 = hash + (read_u64(ptr) * k0); ptr += 8; v0 = rotate_right(v0,33) * k1;
        uint64_t v1 = hash + (read_u64(ptr) * k1); ptr += 8; v1 = rotate_right(v1,33) * k2;
        v0 ^= rotate_right(v0 * k0, 35) + v1;
        v1 ^= rotate_right(v1 * k3, 35) + v0;
        hash += v1;
    }
    
    if ((end - ptr) >= 8)
    {
        hash += read_u64(ptr) * k3; ptr += 8;
        hash ^= rotate_right(hash, 33) * k1;
        
    }
    
    if ((end - ptr) >= 4)
    {
        hash += read_u32(ptr) * k3; ptr += 4;
        hash ^= rotate_right(hash, 15) * k1;
    }
    
    if ((end - ptr) >= 2)
    {
        hash += read_u16(ptr) * k3; ptr += 2;
        hash ^= rotate_right(hash, 13) * k1;
    }
    
    if ((end - ptr) >= 1)
    {
        hash += read_u8 (ptr) * k3;
        hash ^= rotate_right(hash, 25) * k1;
    }
    
    hash ^= rotate_right(hash, 33);
    hash *= k0;
    hash ^= rotate_right(hash, 33);

    memcpy(out, &hash, 8);
}


void metrohash64_2(const uint8_t * key, uint64_t len, uint32_t seed, uint8_t * out)
{
    static const uint64_t k0 = 0xD6D018F5;
    static const uint64_t k1 = 0xA2AA033B;
    static const uint64_t k2 = 0x62992FC1;
    static const uint64_t k3 = 0x30BC5B29; 

    const uint8_t * ptr = reinterpret_cast<const uint8_t*>(key);
    const uint8_t * const end = ptr + len;
    
    uint64_t hash = ((static_cast<uint64_t>(seed) + k2) * k0) + len;
    
    if (len >= 32)
    {
        uint64_t v[4];
        v[0] = hash;
        v[1] = hash;
        v[2] = hash;
        v[3] = hash;
        
        do
        {
            v[0] += read_u64(ptr) * k0; ptr += 8; v[0] = rotate_right(v[0],29) + v[2];
            v[1] += read_u64(ptr) * k1; ptr += 8; v[1] = rotate_right(v[1],29) + v[3];
            v[2] += read_u64(ptr) * k2; ptr += 8; v[2] = rotate_right(v[2],29) + v[0];
            v[3] += read_u64(ptr) * k3; ptr += 8; v[3] = rotate_right(v[3],29) + v[1];
        }
        while (ptr <= (end - 32));

        v[2] ^= rotate_right(((v[0] + v[3]) * k0) + v[1], 30) * k1;
        v[3] ^= rotate_right(((v[1] + v[2]) * k1) + v[0], 30) * k0;
        v[0] ^= rotate_right(((v[0] + v[2]) * k0) + v[3], 30) * k1;
        v[1] ^= rotate_right(((v[1] + v[3]) * k1) + v[2], 30) * k0;
        hash += v[0] ^ v[1];
    }
    
    if ((end - ptr) >= 16)
    {
        uint64_t v0 = hash + (read_u64(ptr) * k2); ptr += 8; v0 = rotate_right(v0,29) * k3;
        uint64_t v1 = hash + (read_u64(ptr) * k2); ptr += 8; v1 = rotate_right(v1,29) * k3;
        v0 ^= rotate_right(v0 * k0, 34) + v1;
        v1 ^= rotate_right(v1 * k3, 34) + v0;
        hash += v1;
    }
    
    if ((end - ptr) >= 8)
    {
        hash += read_u64(ptr) * k3; ptr += 8;
        hash ^= rotate_right(hash, 36) * k1;
    }
    
    if ((end - ptr) >= 4)
    {
        hash += read_u32(ptr) * k3; ptr += 4;
        hash ^= rotate_right(hash, 15) * k1;
    }
    
    if ((end - ptr) >= 2)
    {
        hash += read_u16(ptr) * k3; ptr += 2;
        hash ^= rotate_right(hash, 15) * k1;
    }
    
    if ((end - ptr) >= 1)
    {
        hash += read_u8 (ptr) * k3;
        hash ^= rotate_right(hash, 23) * k1;
    }
    
    hash ^= rotate_right(hash, 28);
    hash *= k0;
    hash ^= rotate_right(hash, 29);

    memcpy(out, &hash, 8);
}