hash.h

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// Copyright Contributors to the OpenImageIO project.
// SPDX-License-Identifier: Apache-2.0
// https://github.com/AcademySoftwareFoundation/OpenImageIO

// clang-format off

/// \file
///
/// Wrapper so that hash_map and hash_set mean what we want regardless
/// of the compiler.
///

#pragma once

#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <unordered_map>
#include <utility>
#include <vector>

#include <OpenImageIO/export.h>
#include <OpenImageIO/oiioversion.h>
#include <OpenImageIO/string_view.h>

// We should never have included fmath.h here. But we did, oops. Once we're
// allowed to break back compatibility, remove it.
#if OIIO_VERSION < OIIO_MAKE_VERSION(3,0,0)
#    include <OpenImageIO/fmath.h>
#endif

#include <OpenImageIO/span.h>


OIIO_NAMESPACE_BEGIN

using std::hash;
using std::unordered_map;

namespace fasthash {

/* The MIT License
   Copyright (C) 2012 Zilong Tan (eric.zltan@gmail.com)
   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.
*/

// Compression function for Merkle-Damgard construction.
// This function is generated using the framework provided.
static inline uint64_t mix(uint64_t h) {
        h ^= h >> 23;
        h *= 0x2127599bf4325c37ULL;
        h ^= h >> 47;
        return h;
}

inline uint64_t fasthash64(const void *buf, size_t len, uint64_t seed=1771)
{
        const uint64_t    m = 0x880355f21e6d1965ULL;
        const uint64_t *pos = (const uint64_t *)buf;
        const uint64_t *end = pos + (len / 8);
        const unsigned char *pos2;
        uint64_t h = seed ^ (len * m);
        uint64_t v;

        while (pos != end) {
                // This appears to be a false positive which only affects GCC.
                // https://godbolt.org/z/5q7Y7ndfb
                OIIO_PRAGMA_WARNING_PUSH
                OIIO_GCC_ONLY_PRAGMA(GCC diagnostic ignored "-Wmaybe-uninitialized")
                v  = *pos++;
                OIIO_PRAGMA_WARNING_POP
                h ^= mix(v);
                h *= m;
        }

        pos2 = (const unsigned char*)pos;
        v = 0;

        switch (len & 7) {
        case 7: v ^= (uint64_t)pos2[6] << 48;
        case 6: v ^= (uint64_t)pos2[5] << 40;
        case 5: v ^= (uint64_t)pos2[4] << 32;
        case 4: v ^= (uint64_t)pos2[3] << 24;
        case 3: v ^= (uint64_t)pos2[2] << 16;
        case 2: v ^= (uint64_t)pos2[1] << 8;
        case 1: v ^= (uint64_t)pos2[0];
                h ^= mix(v);
                h *= m;
        }

        return mix(h);
}

// simplified version for hashing just a few ints
inline uint64_t fasthash64(const std::initializer_list<uint64_t> buf) {
        const uint64_t    m = 0x880355f21e6d1965ULL;
        uint64_t h = (buf.size() * sizeof(uint64_t)) * m;
        for (const uint64_t v : buf) {
                h ^= mix(v);
                h *= m;
        }
        return mix(h);
}

} // namespace fasthash


namespace xxhash {

// xxhash:  https://github.com/Cyan4973/xxHash
// BSD 2-clause license

unsigned int       OIIO_API XXH32 (const void* input, size_t length,
                                   unsigned seed=1771);
unsigned long long OIIO_API XXH64 (const void* input, size_t length,
                                   unsigned long long seed=1771);

inline size_t xxhash (const void* input, size_t length, size_t seed=1771)
{
    return size_t (XXH64 (input, length, (unsigned long long)seed));
}

template <typename Str>
inline size_t xxhash (const Str& s, size_t seed=1771) {
    assert(sizeof(s[0]) == 1);
    return xxhash (s.data(), s.length(), seed);
}

}   // end namespace xxhash




namespace bjhash {

// Bob Jenkins "lookup3" hashes:  http://burtleburtle.net/bob/c/lookup3.c
// It's in the public domain.

OIIO_FORCEINLINE OIIO_HOSTDEVICE uint32_t
rotl32(uint32_t x, int k)
{
#if defined(__CUDA_ARCH__) && __CUDA_ARCH__ >= 320
    return __funnelshift_lc(x, x, k);
#else
    return (x << k) | (x >> (32 - k));
#endif
}

OIIO_FORCEINLINE OIIO_HOSTDEVICE uint64_t
rotl64(uint64_t x, int k)
{
    return (x << k) | (x >> (64 - k));
}

// Mix up the bits of a, b, and c (changing their values in place).
inline OIIO_HOSTDEVICE void bjmix (uint32_t &a, uint32_t &b, uint32_t &c)
{
    a -= c;  a ^= rotl32(c, 4);  c += b;
    b -= a;  b ^= rotl32(a, 6);  a += c;
    c -= b;  c ^= rotl32(b, 8);  b += a;
    a -= c;  a ^= rotl32(c,16);  c += b;
    b -= a;  b ^= rotl32(a,19);  a += c;
    c -= b;  c ^= rotl32(b, 4);  b += a;
}

// Mix up and combine the bits of a, b, and c (doesn't change them, but
// returns a hash of those three original values).  21 ops
inline OIIO_HOSTDEVICE uint32_t bjfinal (uint32_t a, uint32_t b, uint32_t c=0xdeadbeef)
{
    c ^= b; c -= rotl32(b,14);
    a ^= c; a -= rotl32(c,11);
    b ^= a; b -= rotl32(a,25);
    c ^= b; c -= rotl32(b,16);
    a ^= c; a -= rotl32(c,4);
    b ^= a; b -= rotl32(a,14);
    c ^= b; c -= rotl32(b,24);
    return c;
}

// Mix up 4 64-bit inputs (non-destructively), and return a 64 bit hash.
// Adapted from http://burtleburtle.net/bob/c/SpookyV2.h  33 ops
inline uint64_t bjfinal64 (uint64_t h0, uint64_t h1, uint64_t h2, uint64_t h3)
{
    h3 ^= h2;  h2 = rotl64(h2,15);  h3 += h2;
    h0 ^= h3;  h3 = rotl64(h3,52);  h0 += h3;
    h1 ^= h0;  h0 = rotl64(h0,26);  h1 += h0;
    h2 ^= h1;  h1 = rotl64(h1,51);  h2 += h1;
    h3 ^= h2;  h2 = rotl64(h2,28);  h3 += h2;
    h0 ^= h3;  h3 = rotl64(h3,9);   h0 += h3;
    h1 ^= h0;  h0 = rotl64(h0,47);  h1 += h0;
    h2 ^= h1;  h1 = rotl64(h1,54);  h2 += h1;
    h3 ^= h2;  h2 = rotl64(h2,32);  h3 += h2;
    h0 ^= h3;  h3 = rotl64(h3,25);  h0 += h3;
    h1 ^= h0;  h0 = rotl64(h0,63);  h1 += h0;
    return h1;
}

// Standard "lookup3" hash, arbitrary length in bytes.
uint32_t OIIO_API hashlittle (const void *key, size_t length,
                              uint32_t seed=1771);

// Hash an array of 32 bit words -- faster than hashlittle if you know
// it's a whole number of 4-byte words.
uint32_t OIIO_API hashword (const uint32_t *key, size_t nwords,
                            uint32_t seed=1771);

// Hash a string without pre-known length.  We use the Jenkins
// one-at-a-time hash (http://en.wikipedia.org/wiki/Jenkins_hash_function),
// which seems to be a good speed/quality/requirements compromise.
// Note that this is only returning a 32 bit hash space.
inline size_t
strhash (const char *s)
{
    if (! s) return 0;
    unsigned int h = 0;
    while (*s) {
        h += (unsigned char)(*s);
        h += h << 10;
        h ^= h >> 6;
        ++s;
    }
    h += h << 3;
    h ^= h >> 11;
    h += h << 15;
    return h;
}


// Hash a string_view.  We use the Jenkins
// one-at-a-time hash (http://en.wikipedia.org/wiki/Jenkins_hash_function),
// which seems to be a good speed/quality/requirements compromise.
// Note that this is only returning a 32 bit hash space.
inline size_t
strhash (string_view s)
{
    size_t len = s.length();
    if (! len) return 0;
    unsigned int h = 0;
    for (size_t i = 0;  i < len;  ++i) {
        h += (unsigned char)(s[i]);
        h += h << 10;
        h ^= h >> 6;
    }
    h += h << 3;
    h ^= h >> 11;
    h += h << 15;
    return h;
}

}   // end namespace bjhash


namespace murmur {

// These functions were lifted from the public domain Murmurhash3.  We
// don't bother using Murmurhash -- in my tests, it was slower than
// xxhash in all cases, and comparable to bjhash.  But these two fmix
// functions are useful for scrambling the bits of a single 32 or 64 bit
// value.

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

inline uint64_t fmix (uint64_t k)
{
    k ^= k >> 33;
    k *= 0xff51afd7ed558ccdULL;
    k ^= k >> 33;
    k *= 0xc4ceb9fe1a85ec53ULL;
    k ^= k >> 33;
    return k;
}

}  // end namespace murmur



namespace farmhash {

// Copyright (c) 2014 Google, Inc.
// https://github.com/google/farmhash
// See OpenImageIO's hashes.cpp for the MIT license for this code.


#if defined(FARMHASH_UINT128_T_DEFINED)

OIIO_HOSTDEVICE inline constexpr uint64_t Uint128Low64(const uint128_t x) {
    return static_cast<uint64_t>(x);
}

OIIO_HOSTDEVICE inline constexpr uint64_t Uint128High64(const uint128_t x) {
    return static_cast<uint64_t>(x >> 64);
}

OIIO_HOSTDEVICE inline constexpr uint128_t Uint128(uint64_t lo, uint64_t hi) {
    return lo + (((uint128_t)hi) << 64);
}

OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 void
CopyUint128(uint128_t &dst, const uint128_t src) {
    dst = src;
}

#else

typedef std::pair<uint64_t, uint64_t> uint128_t;
OIIO_HOSTDEVICE inline constexpr uint64_t Uint128Low64(const uint128_t x) {
    return x.first;
}

OIIO_HOSTDEVICE inline constexpr uint64_t Uint128High64(const uint128_t x) {
    return x.second;
}

OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 uint128_t Uint128(uint64_t lo, uint64_t hi) {
    return uint128_t(lo, hi);
}

OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 void
CopyUint128(uint128_t &dst, const uint128_t src) {
    dst.first  = src.first;
    dst.second = src.second;

}
#endif


// BASIC STRING HASHING

// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
size_t OIIO_API Hash(const char* s, size_t len);

// Hash function for a byte array.  Most useful in 32-bit binaries.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint32_t OIIO_API Hash32(const char* s, size_t len);

// Hash function for a byte array.  For convenience, a 32-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint32_t OIIO_API Hash32WithSeed(const char* s, size_t len, uint32_t seed);

// Hash 128 input bits down to 64 bits of output.
// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint64_t OIIO_API Hash64(const char* s, size_t len);

// Hash function for a byte array.  For convenience, a 64-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint64_t OIIO_API Hash64WithSeed(const char* s, size_t len, uint64_t seed);

// Hash function for a byte array.  For convenience, two seeds are also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint64_t OIIO_API Hash64WithSeeds(const char* s, size_t len,
                                  uint64_t seed0, uint64_t seed1);

// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint128_t OIIO_API Hash128(const char* s, size_t len);

// Hash function for a byte array.  For convenience, a 128-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
uint128_t OIIO_API Hash128WithSeed(const char* s, size_t len, uint128_t seed);

// BASIC NON-STRING HASHING

// This is intended to be a reasonably good hash function.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 uint64_t Hash128to64(uint128_t x) {
  // Murmur-inspired hashing.
  const uint64_t kMul = 0x9ddfea08eb382d69ULL;
  uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
  a ^= (a >> 47);
  uint64_t b = (Uint128High64(x) ^ a) * kMul;
  b ^= (b >> 47);
  b *= kMul;
  return b;
}

// FINGERPRINTING (i.e., good, portable, forever-fixed hash functions)

// Fingerprint function for a byte array.  Most useful in 32-bit binaries.
uint32_t OIIO_API Fingerprint32(const char* s, size_t len);

// Fingerprint function for a byte array.
uint64_t OIIO_API Fingerprint64(const char* s, size_t len);

// Fingerprint function for a byte array.
uint128_t OIIO_API Fingerprint128(const char* s, size_t len);

// This is intended to be a good fingerprinting primitive.
// See below for more overloads.
OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 uint64_t Fingerprint(uint128_t x) {
  // Murmur-inspired hashing.
  const uint64_t kMul = 0x9ddfea08eb382d69ULL;
  uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
  a ^= (a >> 47);
  uint64_t b = (Uint128High64(x) ^ a) * kMul;
  b ^= (b >> 44);
  b *= kMul;
  b ^= (b >> 41);
  b *= kMul;
  return b;
}

// This is intended to be a good fingerprinting primitive.
OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14 uint64_t Fingerprint(uint64_t x) {
  // Murmur-inspired hashing.
  const uint64_t kMul = 0x9ddfea08eb382d69ULL;
  uint64_t b = x * kMul;
  b ^= (b >> 44);
  b *= kMul;
  b ^= (b >> 41);
  b *= kMul;
  return b;
}

#ifndef FARMHASH_NO_CXX_STRING

// Convenience functions to hash or fingerprint C++ strings.
// These require that Str::data() return a pointer to the first char
// (as a const char*) and that Str::length() return the string's length;
// they work with std::string, for example.

// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline size_t Hash(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Hash(s.data(), s.length());
}

// Hash function for a byte array.  Most useful in 32-bit binaries.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint32_t Hash32(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Hash32(s.data(), s.length());
}

// Hash function for a byte array.  For convenience, a 32-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint32_t Hash32WithSeed(const Str& s, uint32_t seed) {
  assert(sizeof(s[0]) == 1);
  return Hash32WithSeed(s.data(), s.length(), seed);
}

// Hash 128 input bits down to 64 bits of output.
// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint64_t Hash64(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Hash64(s.data(), s.length());
}

// Hash function for a byte array.  For convenience, a 64-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint64_t Hash64WithSeed(const Str& s, uint64_t seed) {
  assert(sizeof(s[0]) == 1);
  return Hash64WithSeed(s.data(), s.length(), seed);
}

// Hash function for a byte array.  For convenience, two seeds are also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint64_t Hash64WithSeeds(const Str& s, uint64_t seed0, uint64_t seed1) {
  assert(sizeof(s[0]) == 1);
  return Hash64WithSeeds(s.data(), s.length(), seed0, seed1);
}

// Hash function for a byte array.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint128_t Hash128(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Hash128(s.data(), s.length());
}

// Hash function for a byte array.  For convenience, a 128-bit seed is also
// hashed into the result.
// May change from time to time, may differ on different platforms, may differ
// depending on NDEBUG.
template <typename Str>
inline uint128_t Hash128WithSeed(const Str& s, uint128_t seed) {
  assert(sizeof(s[0]) == 1);
  return Hash128(s.data(), s.length(), seed);
}

// FINGERPRINTING (i.e., good, portable, forever-fixed hash functions)

// Fingerprint function for a byte array.  Most useful in 32-bit binaries.
template <typename Str>
inline uint32_t Fingerprint32(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Fingerprint32(s.data(), s.length());
}

// Fingerprint 128 input bits down to 64 bits of output.
// Fingerprint function for a byte array.
template <typename Str>
inline uint64_t Fingerprint64(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Fingerprint64(s.data(), s.length());
}

// Fingerprint function for a byte array.
template <typename Str>
inline uint128_t Fingerprint128(const Str& s) {
  assert(sizeof(s[0]) == 1);
  return Fingerprint128(s.data(), s.length());
}

#endif

}  // namespace farmhash




class CSHA1;  // opaque forward declaration


/// Class that encapsulates SHA-1 hashing, a crypticographic-strength
/// 160-bit hash function.  It's not as fast as our other hashing
/// methods, but has an extremely low chance of having collisions.
class OIIO_API SHA1 {
public:
    /// Create SHA1, optionally read data
    SHA1 (const void *data=NULL, size_t size=0);
    ~SHA1 ();

    /// Append more data
    void append (const void *data, size_t size);

    /// Append more data from a string_view
    void append (string_view s) {
        append(s.data(), s.size());
    }

    /// Append more data from a span, without thinking about sizes.
    template<class T> void append (span<T> v) {
        append (v.data(), v.size()*sizeof(T));
    }

    /// Type for storing the raw bits of the hash
    struct Hash {
        unsigned char hash[20];
    };

    /// Get the digest and store it in Hash h.
    void gethash (Hash &h);

    /// Get the digest and store it in h (must point to enough storage
    /// to accommodate 20 bytes).
    void gethash (void *h) { gethash (*(Hash *)h); }

    /// Return the digest as a hex string
    std::string digest ();

    /// Roll the whole thing into one functor, return the string digest.
    static std::string digest (const void *data, size_t size) {
        SHA1 s (data, size);  return s.digest();
    }

private:
    CSHA1 *m_csha1;
    bool m_final;
};


OIIO_NAMESPACE_END