// Copyright (c) 2011 Google, Inc.

//

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included in

// all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

// THE SOFTWARE.

//

// CityHash, by Geoff Pike and Jyrki Alakuijala

//

// This file provides CityHash64() and related functions.

//

// It's probably possible to create even faster hash functions by

// writing a program that systematically explores some of the space of

// possible hash functions, by using SIMD instructions, or by

// compromising on hash quality.

#include "config.h"

#include <city.h>

#include <algorithm>

#include <string.h>  // for memcpy and memset

using namespace std;

static uint64 UNALIGNED_LOAD64(const char *p) {

  uint64 result;

  memcpy(&result, p, sizeof(result));

  return result;

}

static uint32 UNALIGNED_LOAD32(const char *p) {

  uint32 result;

  memcpy(&result, p, sizeof(result));

  return result;

}

#ifdef _MSC_VER

#include <stdlib.h>

#define bswap_32(x) _byteswap_ulong(x)

#define bswap_64(x) _byteswap_uint64(x)

#elif defined(__APPLE__)

// Mac OS X / Darwin features

#include <libkern/OSByteOrder.h>

#define bswap_32(x) OSSwapInt32(x)

#define bswap_64(x) OSSwapInt64(x)

#elif defined(__sun) || defined(sun)

#include <sys/byteorder.h>

#define bswap_32(x) BSWAP_32(x)

#define bswap_64(x) BSWAP_64(x)

#elif defined(__FreeBSD__)

#include <sys/endian.h>

#define bswap_32(x) bswap32(x)

#define bswap_64(x) bswap64(x)

#elif defined(__OpenBSD__)

#include <sys/types.h>

#define bswap_32(x) swap32(x)

#define bswap_64(x) swap64(x)

#elif defined(__NetBSD__)

#include <sys/types.h>

#include <machine/bswap.h>

#if defined(__BSWAP_RENAME) && !defined(__bswap_32)

#define bswap_32(x) bswap32(x)

#define bswap_64(x) bswap64(x)

#endif

#else

#include <byteswap.h>

#endif

#ifdef WORDS_BIGENDIAN

#define uint32_in_expected_order(x) (bswap_32(x))

#define uint64_in_expected_order(x) (bswap_64(x))

#else

#define uint32_in_expected_order(x) (x)

#define uint64_in_expected_order(x) (x)

#endif

#if !defined(LIKELY)

#if HAVE_BUILTIN_EXPECT

#define LIKELY(x) (__builtin_expect(!!(x), 1))

#else

#define LIKELY(x) (x)

#endif

#endif

static uint64 Fetch64(const char *p) {

  return uint64_in_expected_order(UNALIGNED_LOAD64(p));

}

static uint32 Fetch32(const char *p) {

  return uint32_in_expected_order(UNALIGNED_LOAD32(p));

}

// Some primes between 2^63 and 2^64 for various uses.

static const uint64 k0 = 0xc3a5c85c97cb3127ULL;

static const uint64 k1 = 0xb492b66fbe98f273ULL;

static const uint64 k2 = 0x9ae16a3b2f90404fULL;

// Magic numbers for 32-bit hashing.  Copied from Murmur3.

static const uint32 c1 = 0xcc9e2d51;

static const uint32 c2 = 0x1b873593;

// A 32-bit to 32-bit integer hash copied from Murmur3.

static uint32 fmix(uint32 h)

{

  h ^= h >> 16;

  h *= 0x85ebca6b;

  h ^= h >> 13;

  h *= 0xc2b2ae35;

  h ^= h >> 16;

  return h;

}

static uint32 Rotate32(uint32 val, int shift) {

  // Avoid shifting by 32: doing so yields an undefined result.

  return shift == 0 ? val : ((val >> shift) | (val << (32 - shift)));

}

#undef PERMUTE3

#define PERMUTE3(a, b, c) do { std::swap(a, b); std::swap(a, c); } while (0)

static uint32 Mur(uint32 a, uint32 h) {

  // Helper from Murmur3 for combining two 32-bit values.

  a *= c1;

  a = Rotate32(a, 17);

  a *= c2;

  h ^= a;

  h = Rotate32(h, 19);

  return h * 5 + 0xe6546b64;

}

static uint32 Hash32Len13to24(const char *s, size_t len) {

  uint32 a = Fetch32(s - 4 + (len >> 1));

  uint32 b = Fetch32(s + 4);

  uint32 c = Fetch32(s + len - 8);

  uint32 d = Fetch32(s + (len >> 1));

  uint32 e = Fetch32(s);

  uint32 f = Fetch32(s + len - 4);

  uint32 h = static_cast<uint32>(len);

  return fmix(Mur(f, Mur(e, Mur(d, Mur(c, Mur(b, Mur(a, h)))))));

}

static uint32 Hash32Len0to4(const char *s, size_t len) {

  uint32 b = 0;

  uint32 c = 9;

  for (size_t i = 0; i < len; i++) {

    signed char v = static_cast<signed char>(s[i]);

    b = b * c1 + static_cast<uint32>(v);

    c ^= b;

  }

  return fmix(Mur(b, Mur(static_cast<uint32>(len), c)));

}

static uint32 Hash32Len5to12(const char *s, size_t len) {

  uint32 a = static_cast<uint32>(len), b = a * 5, c = 9, d = b;

  a += Fetch32(s);

  b += Fetch32(s + len - 4);

  c += Fetch32(s + ((len >> 1) & 4));

  return fmix(Mur(c, Mur(b, Mur(a, d))));

}

uint32 CityHash32(const char *s, size_t len) {

  if (len <= 24) {

    return len <= 12 ?

        (len <= 4 ? Hash32Len0to4(s, len) : Hash32Len5to12(s, len)) :

        Hash32Len13to24(s, len);

  }

  // len > 24

  uint32 h = static_cast<uint32>(len), g = c1 * h, f = g;

  uint32 a0 = Rotate32(Fetch32(s + len - 4) * c1, 17) * c2;

  uint32 a1 = Rotate32(Fetch32(s + len - 8) * c1, 17) * c2;

  uint32 a2 = Rotate32(Fetch32(s + len - 16) * c1, 17) * c2;

  uint32 a3 = Rotate32(Fetch32(s + len - 12) * c1, 17) * c2;

  uint32 a4 = Rotate32(Fetch32(s + len - 20) * c1, 17) * c2;

  h ^= a0;

  h = Rotate32(h, 19);

  h = h * 5 + 0xe6546b64;

  h ^= a2;

  h = Rotate32(h, 19);

  h = h * 5 + 0xe6546b64;

  g ^= a1;

  g = Rotate32(g, 19);

  g = g * 5 + 0xe6546b64;

  g ^= a3;

  g = Rotate32(g, 19);

  g = g * 5 + 0xe6546b64;

  f += a4;

  f = Rotate32(f, 19);

  f = f * 5 + 0xe6546b64;

  size_t iters = (len - 1) / 20;

  do {

    uint32 a0 = Rotate32(Fetch32(s) * c1, 17) * c2;

    uint32 a1 = Fetch32(s + 4);

    uint32 a2 = Rotate32(Fetch32(s + 8) * c1, 17) * c2;

    uint32 a3 = Rotate32(Fetch32(s + 12) * c1, 17) * c2;

    uint32 a4 = Fetch32(s + 16);

    h ^= a0;

    h = Rotate32(h, 18);

    h = h * 5 + 0xe6546b64;

    f += a1;

    f = Rotate32(f, 19);

    f = f * c1;

    g += a2;

    g = Rotate32(g, 18);

    g = g * 5 + 0xe6546b64;

    h ^= a3 + a1;

    h = Rotate32(h, 19);

    h = h * 5 + 0xe6546b64;

    g ^= a4;

    g = bswap_32(g) * 5;

    h += a4 * 5;

    h = bswap_32(h);

    f += a0;

    PERMUTE3(f, h, g);

    s += 20;

  } while (--iters != 0);

  g = Rotate32(g, 11) * c1;

  g = Rotate32(g, 17) * c1;

  f = Rotate32(f, 11) * c1;

  f = Rotate32(f, 17) * c1;

  h = Rotate32(h + g, 19);

  h = h * 5 + 0xe6546b64;

  h = Rotate32(h, 17) * c1;

  h = Rotate32(h + f, 19);

  h = h * 5 + 0xe6546b64;

  h = Rotate32(h, 17) * c1;

  return h;

}

// Bitwise right rotate.  Normally this will compile to a single

// instruction, especially if the shift is a manifest constant.

static uint64 Rotate(uint64 val, int shift) {

  // Avoid shifting by 64: doing so yields an undefined result.

  return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));

}

static uint64 ShiftMix(uint64 val) {

  return val ^ (val >> 47);

}

static uint64 HashLen16(uint64 u, uint64 v) {

  return Hash128to64(uint128(u, v));

}

static uint64 HashLen16(uint64 u, uint64 v, uint64 mul) {

  // Murmur-inspired hashing.

  uint64 a = (u ^ v) * mul;

  a ^= (a >> 47);

  uint64 b = (v ^ a) * mul;

  b ^= (b >> 47);

  b *= mul;

  return b;

}

static uint64 HashLen0to16(const char *s, size_t len) {

  if (len >= 8) {

    uint64 mul = k2 + len * 2;

    uint64 a = Fetch64(s) + k2;

    uint64 b = Fetch64(s + len - 8);

    uint64 c = Rotate(b, 37) * mul + a;

    uint64 d = (Rotate(a, 25) + b) * mul;

    return HashLen16(c, d, mul);

  }

  if (len >= 4) {

    uint64 mul = k2 + len * 2;

    uint64 a = Fetch32(s);

    return HashLen16(len + (a << 3), Fetch32(s + len - 4), mul);

  }

  if (len > 0) {

    uint8 a = static_cast<uint8>(s[0]);

    uint8 b = static_cast<uint8>(s[len >> 1]);

    uint8 c = static_cast<uint8>(s[len - 1]);

    uint32 y = static_cast<uint32>(a) + (static_cast<uint32>(b) << 8);

    uint32 z = static_cast<uint32>(len) + (static_cast<uint32>(c) << 2);

    return ShiftMix(y * k2 ^ z * k0) * k2;

  }

  return k2;

}

// This probably works well for 16-byte strings as well, but it may be overkill

// in that case.

static uint64 HashLen17to32(const char *s, size_t len) {

  uint64 mul = k2 + len * 2;

  uint64 a = Fetch64(s) * k1;

  uint64 b = Fetch64(s + 8);

  uint64 c = Fetch64(s + len - 8) * mul;

  uint64 d = Fetch64(s + len - 16) * k2;

  return HashLen16(Rotate(a + b, 43) + Rotate(c, 30) + d,

                   a + Rotate(b + k2, 18) + c, mul);

}

// Return a 16-byte hash for 48 bytes.  Quick and dirty.

// Callers do best to use "random-looking" values for a and b.

static pair<uint64, uint64> WeakHashLen32WithSeeds(

    uint64 w, uint64 x, uint64 y, uint64 z, uint64 a, uint64 b) {

  a += w;

  b = Rotate(b + a + z, 21);

  uint64 c = a;

  a += x;

  a += y;

  b += Rotate(a, 44);

  return make_pair(a + z, b + c);

}

// Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.

static pair<uint64, uint64> WeakHashLen32WithSeeds(

    const char* s, uint64 a, uint64 b) {

  return WeakHashLen32WithSeeds(Fetch64(s),

                                Fetch64(s + 8),

                                Fetch64(s + 16),

                                Fetch64(s + 24),

                                a,

                                b);

}

// Return an 8-byte hash for 33 to 64 bytes.

static uint64 HashLen33to64(const char *s, size_t len) {

  uint64 mul = k2 + len * 2;

  uint64 a = Fetch64(s) * k2;

  uint64 b = Fetch64(s + 8);

  uint64 c = Fetch64(s + len - 24);

  uint64 d = Fetch64(s + len - 32);

  uint64 e = Fetch64(s + 16) * k2;

  uint64 f = Fetch64(s + 24) * 9;

  uint64 g = Fetch64(s + len - 8);

  uint64 h = Fetch64(s + len - 16) * mul;

  uint64 u = Rotate(a + g, 43) + (Rotate(b, 30) + c) * 9;

  uint64 v = ((a + g) ^ d) + f + 1;

  uint64 w = bswap_64((u + v) * mul) + h;

  uint64 x = Rotate(e + f, 42) + c;

  uint64 y = (bswap_64((v + w) * mul) + g) * mul;

  uint64 z = e + f + c;

  a = bswap_64((x + z) * mul + y) + b;

  b = ShiftMix((z + a) * mul + d + h) * mul;

  return b + x;

}

uint64 CityHash64(const char *s, size_t len) {

  if (len <= 32) {

    if (len <= 16) {

      return HashLen0to16(s, len);

    } else {

      return HashLen17to32(s, len);

    }

  } else if (len <= 64) {

    return HashLen33to64(s, len);

  }

  // For strings over 64 bytes we hash the end first, and then as we

  // loop we keep 56 bytes of state: v, w, x, y, and z.

  uint64 x = Fetch64(s + len - 40);

  uint64 y = Fetch64(s + len - 16) + Fetch64(s + len - 56);

  uint64 z = HashLen16(Fetch64(s + len - 48) + len, Fetch64(s + len - 24));

  pair<uint64, uint64> v = WeakHashLen32WithSeeds(s + len - 64, len, z);

  pair<uint64, uint64> w = WeakHashLen32WithSeeds(s + len - 32, y + k1, x);

  x = x * k1 + Fetch64(s);

  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.

  len = (len - 1) & ~static_cast<size_t>(63);

  do {

    x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;

    y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;

    x ^= w.second;

    y += v.first + Fetch64(s + 40);

    z = Rotate(z + w.first, 33) * k1;

    v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);

    w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));

    std::swap(z, x);

    s += 64;

    len -= 64;

  } while (len != 0);

  return HashLen16(HashLen16(v.first, w.first) + ShiftMix(y) * k1 + z,

                   HashLen16(v.second, w.second) + x);

}

uint64 CityHash64WithSeed(const char *s, size_t len, uint64 seed) {

  return CityHash64WithSeeds(s, len, k2, seed);

}

uint64 CityHash64WithSeeds(const char *s, size_t len,

                           uint64 seed0, uint64 seed1) {

  return HashLen16(CityHash64(s, len) - seed0, seed1);

}

// A subroutine for CityHash128().  Returns a decent 128-bit hash for strings

// of any length representable in signed long.  Based on City and Murmur.

static uint128 CityMurmur(const char *s, size_t len, uint128 seed) {

  uint64 a = Uint128Low64(seed);

  uint64 b = Uint128High64(seed);

  uint64 c = 0;

  uint64 d = 0;

  if (len <= 16) {

    a = ShiftMix(a * k1) * k1;

    c = b * k1 + HashLen0to16(s, len);

    d = ShiftMix(a + (len >= 8 ? Fetch64(s) : c));

  } else {

    c = HashLen16(Fetch64(s + len - 8) + k1, a);

    d = HashLen16(b + len, c + Fetch64(s + len - 16));

    a += d;

    // len > 16 here, so do...while is safe

    do {

      a ^= ShiftMix(Fetch64(s) * k1) * k1;

      a *= k1;

      b ^= a;

      c ^= ShiftMix(Fetch64(s + 8) * k1) * k1;

      c *= k1;

      d ^= c;

      s += 16;

      len -= 16;

    } while (len > 16);

  }

  a = HashLen16(a, c);

  b = HashLen16(d, b);

  return uint128(a ^ b, HashLen16(b, a));

}

uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed) {

  if (len < 128) {

    return CityMurmur(s, len, seed);

  }

  // We expect len >= 128 to be the common case.  Keep 56 bytes of state:

  // v, w, x, y, and z.

  pair<uint64, uint64> v, w;

  uint64 x = Uint128Low64(seed);

  uint64 y = Uint128High64(seed);

  uint64 z = len * k1;

  v.first = Rotate(y ^ k1, 49) * k1 + Fetch64(s);

  v.second = Rotate(v.first, 42) * k1 + Fetch64(s + 8);

  w.first = Rotate(y + z, 35) * k1 + x;

  w.second = Rotate(x + Fetch64(s + 88), 53) * k1;

  // This is the same inner loop as CityHash64(), manually unrolled.

  do {

    x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;

    y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;

    x ^= w.second;

    y += v.first + Fetch64(s + 40);

    z = Rotate(z + w.first, 33) * k1;

    v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);

    w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));

    std::swap(z, x);

    s += 64;

    x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;

    y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;

    x ^= w.second;

    y += v.first + Fetch64(s + 40);

    z = Rotate(z + w.first, 33) * k1;

    v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);

    w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));

    std::swap(z, x);

    s += 64;

    len -= 128;

  } while (LIKELY(len >= 128));

  x += Rotate(v.first + z, 49) * k0;

  y = y * k0 + Rotate(w.second, 37);

  z = z * k0 + Rotate(w.first, 27);

  w.first *= 9;

  v.first *= k0;

  // If 0 < len < 128, hash up to 4 chunks of 32 bytes each from the end of s.

  for (size_t tail_done = 0; tail_done < len; ) {

    tail_done += 32;

    y = Rotate(x + y, 42) * k0 + v.second;

    w.first += Fetch64(s + len - tail_done + 16);

    x = x * k0 + w.first;

    z += w.second + Fetch64(s + len - tail_done);

    w.second += v.first;

    v = WeakHashLen32WithSeeds(s + len - tail_done, v.first + z, v.second);

    v.first *= k0;

  }

  // At this point our 56 bytes of state should contain more than

  // enough information for a strong 128-bit hash.  We use two

  // different 56-byte-to-8-byte hashes to get a 16-byte final result.

  x = HashLen16(x, v.first);

  y = HashLen16(y + z, w.first);

  return uint128(HashLen16(x + v.second, w.second) + y,

                 HashLen16(x + w.second, y + v.second));

}

uint128 CityHash128(const char *s, size_t len) {

  return len >= 16 ?

      CityHash128WithSeed(s + 16, len - 16,

                          uint128(Fetch64(s), Fetch64(s + 8) + k0)) :

      CityHash128WithSeed(s, len, uint128(k0, k1));

}

#ifdef __SSE4_2__

#include <citycrc.h>

#include <nmmintrin.h>

// Requires len >= 240.

static void CityHashCrc256Long(const char *s, size_t len,

                               uint32 seed, uint64 *result) {

  uint64 a = Fetch64(s + 56) + k0;

  uint64 b = Fetch64(s + 96) + k0;

  uint64 c = result[0] = HashLen16(b, len);

  uint64 d = result[1] = Fetch64(s + 120) * k0 + len;

  uint64 e = Fetch64(s + 184) + seed;

  uint64 f = 0;

  uint64 g = 0;

  uint64 h = c + d;

  uint64 x = seed;

  uint64 y = 0;

  uint64 z = 0;

  // 240 bytes of input per iter.

  size_t iters = len / 240;

  len -= iters * 240;

  do {

#undef CHUNK

#define CHUNK(r)                                \

    PERMUTE3(x, z, y);                          \

    b += Fetch64(s);                            \

    c += Fetch64(s + 8);                        \

    d += Fetch64(s + 16);                       \

    e += Fetch64(s + 24);                       \

    f += Fetch64(s + 32);                       \

    a += b;                                     \

    h += f;                                     \

    b += c;                                     \

    f += d;                                     \

    g += e;                                     \

    e += z;                                     \

    g += x;                                     \

    z = _mm_crc32_u64(z, b + g);                \

    y = _mm_crc32_u64(y, e + h);                \

    x = _mm_crc32_u64(x, f + a);                \

    e = Rotate(e, r);                           \

    c += e;                                     \

    s += 40

    CHUNK(0); PERMUTE3(a, h, c);

    CHUNK(33); PERMUTE3(a, h, f);

    CHUNK(0); PERMUTE3(b, h, f);

    CHUNK(42); PERMUTE3(b, h, d);

    CHUNK(0); PERMUTE3(b, h, e);

    CHUNK(33); PERMUTE3(a, h, e);

  } while (--iters > 0);

  while (len >= 40) {

    CHUNK(29);

    e ^= Rotate(a, 20);

    h += Rotate(b, 30);

    g ^= Rotate(c, 40);

    f += Rotate(d, 34);

    PERMUTE3(c, h, g);

    len -= 40;

  }

  if (len > 0) {

    s = s + len - 40;

    CHUNK(33);

    e ^= Rotate(a, 43);

    h += Rotate(b, 42);

    g ^= Rotate(c, 41);

    f += Rotate(d, 40);

  }

  result[0] ^= h;

  result[1] ^= g;

  g += h;

  a = HashLen16(a, g + z);

  x += y << 32;

  b += x;

  c = HashLen16(c, z) + h;

  d = HashLen16(d, e + result[0]);

  g += e;

  h += HashLen16(x, f);

  e = HashLen16(a, d) + g;

  z = HashLen16(b, c) + a;

  y = HashLen16(g, h) + c;

  result[0] = e + z + y + x;

  a = ShiftMix((a + y) * k0) * k0 + b;

  result[1] += a + result[0];

  a = ShiftMix(a * k0) * k0 + c;

  result[2] = a + result[1];

  a = ShiftMix((a + e) * k0) * k0;

  result[3] = a + result[2];

}

// Requires len < 240.

static void CityHashCrc256Short(const char *s, size_t len, uint64 *result) {

  char buf[240];

  memcpy(buf, s, len);

  memset(buf + len, 0, 240 - len);

  CityHashCrc256Long(buf, 240, ~static_cast<uint32>(len), result);

}

void CityHashCrc256(const char *s, size_t len, uint64 *result) {

  if (LIKELY(len >= 240)) {

    CityHashCrc256Long(s, len, 0, result);

  } else {

    CityHashCrc256Short(s, len, result);

  }

}

uint128 CityHashCrc128WithSeed(const char *s, size_t len, uint128 seed) {

  if (len <= 900) {

    return CityHash128WithSeed(s, len, seed);

  } else {

    uint64 result[4];

    CityHashCrc256(s, len, result);

    uint64 u = Uint128High64(seed) + result[0];

    uint64 v = Uint128Low64(seed) + result[1];

    return uint128(HashLen16(u, v + result[2]),

                   HashLen16(Rotate(v, 32), u * k0 + result[3]));

  }

}

uint128 CityHashCrc128(const char *s, size_t len) {

  if (len <= 900) {

    return CityHash128(s, len);

  } else {

    uint64 result[4];

    CityHashCrc256(s, len, result);

    return uint128(result[2], result[3]);

  }

}

#endif