text: /*
   * Copyright 2017-2019 Leonid Yuriev <leo@yuriev.ru>
   * and other libmdbx authors: please see AUTHORS file.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted only as authorized by the OpenLDAP
   * Public License.
   *
   * A copy of this license is available in the file LICENSE in the
   * top-level directory of the distribution or, alternatively, at
   * <http://www.OpenLDAP.org/license.html>.
   */
  
  #pragma once
  #include "base.h"
  
  #if !defined(__BYTE_ORDER__) || !defined(__ORDER_LITTLE_ENDIAN__) ||           \
      !defined(__ORDER_BIG_ENDIAN__)
  #error __BYTE_ORDER__ should be defined.
  #endif
  
  #if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__ &&                               \
      __BYTE_ORDER__ != __ORDER_BIG_ENDIAN__
  #error Unsupported byte order.
  #endif
  
  #if __GNUC_PREREQ(4, 4) || defined(__clang__)
  #ifndef bswap64
  #define bswap64(v) __builtin_bswap64(v)
  #endif
  #ifndef bswap32
  #define bswap32(v) __builtin_bswap32(v)
  #endif
  #if (__GNUC_PREREQ(4, 8) || __has_builtin(__builtin_bswap16)) &&               \
      !defined(bswap16)
  #define bswap16(v) __builtin_bswap16(v)
  #endif
  
  #elif defined(_MSC_VER)
  
  #if _MSC_FULL_VER < 190024215
  #pragma message(                                                               \
      "It is recommended to use Visual Studio 2015 (MSC 19.0) or newer.")
  #endif
  
  #define bswap64(v) _byteswap_uint64(v)
  #define bswap32(v) _byteswap_ulong(v)
  #define bswap16(v) _byteswap_ushort(v)
  #define rot64(v, s) _rotr64(v, s)
  #define rot32(v, s) _rotr(v, s)
  
  #if defined(_M_ARM64) || defined(_M_X64) || defined(_M_IA64)
  #pragma intrinsic(_umul128)
  #define mul_64x64_128(a, b, ph) _umul128(a, b, ph)
  #pragma intrinsic(__umulh)
  #define mul_64x64_high(a, b) __umulh(a, b)
  #endif
  
  #if defined(_M_IX86)
  #pragma intrinsic(__emulu)
  #define mul_32x32_64(a, b) __emulu(a, b)
  #elif defined(_M_ARM)
  #define mul_32x32_64(a, b) _arm_umull(a, b)
  #endif
  
  #endif /* compiler */
  
  #ifndef bswap64
  #ifdef __bswap_64
  #define bswap64(v) __bswap_64(v)
  #else
  static __inline uint64_t bswap64(uint64_t v) {
    return v << 56 | v >> 56 | ((v << 40) & UINT64_C(0x00ff000000000000)) |
           ((v << 24) & UINT64_C(0x0000ff0000000000)) |
           ((v << 8) & UINT64_C(0x000000ff00000000)) |
           ((v >> 8) & UINT64_C(0x00000000ff0000000)) |
           ((v >> 24) & UINT64_C(0x0000000000ff0000)) |
           ((v >> 40) & UINT64_C(0x000000000000ff00));
  }
  #endif
  #endif /* bswap64 */
  
  #ifndef bswap32
  #ifdef __bswap_32
  #define bswap32(v) __bswap_32(v)
  #else
  static __inline uint32_t bswap32(uint32_t v) {
    return v << 24 | v >> 24 | ((v << 8) & UINT32_C(0x00ff0000)) |
           ((v >> 8) & UINT32_C(0x0000ff00));
  }
  #endif
  #endif /* bswap32 */
  
  #ifndef bswap16
  #ifdef __bswap_16
  #define bswap16(v) __bswap_16(v)
  #else
  static __inline uint16_t bswap16(uint16_t v) { return v << 8 | v >> 8; }
  #endif
  #endif /* bswap16 */
  
  #define is_byteorder_le() (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
  #define is_byteorder_be() (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
  
  #ifndef htole16
  #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  #define htobe16(v) bswap16(v)
  #define htole16(v) (v)
  #define be16toh(v) bswap16(v)
  #define le16toh(v) (v)
  #else
  #define htobe16(v) (v)
  #define htole16(v) bswap16(v)
  #define be16toh(v) (v)
  #define le16toh(v) bswap16(v)
  #endif
  #endif /* htole16 */
  
  #ifndef htole32
  #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  #define htobe32(v) bswap32(v)
  #define htole32(v) (v)
  #define be32toh(v) bswap32(v)
  #define le32toh(v) (v)
  #else
  #define htobe32(v) (v)
  #define htole32(v) bswap32(v)
  #define be32toh(v) (v)
  #define le32toh(v) bswap32(v)
  #endif
  #endif /* htole32 */
  
  #ifndef htole64
  #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  #define htobe64(v) bswap64(v)
  #define htole64(v) (v)
  #define be64toh(v) bswap64(v)
  #define le64toh(v) (v)
  #else
  #define htobe64(v) (v)
  #define htole64(v) bswap_64(v)
  #define be64toh(v) (v)
  #define le64toh(v) bswap_64(v)
  #endif
  #endif /* htole64 */
  
  namespace unaligned {
  
  template <typename T> static __inline T load(const void *ptr) {
  #if defined(_MSC_VER) &&                                                       \
      (defined(_M_ARM64) || defined(_M_X64) || defined(_M_IA64))
    return *(const T __unaligned *)ptr;
  #elif MDBX_UNALIGNED_OK
    return *(const T *)ptr;
  #else
    T local;
  #if defined(__GNUC__) || defined(__clang__)
    __builtin_memcpy(&local, (const T *)ptr, sizeof(T));
  #else
    memcpy(&local, (const T *)ptr, sizeof(T));
  #endif /* __GNUC__ || __clang__ */
    return local;
  #endif /* MDBX_UNALIGNED_OK */
  }
  
  template <typename T> static __inline void store(void *ptr, const T &value) {
  #if defined(_MSC_VER) &&                                                       \
      (defined(_M_ARM64) || defined(_M_X64) || defined(_M_IA64))
    *((T __unaligned *)ptr) = value;
  #elif MDBX_UNALIGNED_OK
    *(volatile T *)ptr = value;
  #else
  #if defined(__GNUC__) || defined(__clang__)
    __builtin_memcpy(ptr, &value, sizeof(T));
  #else
    memcpy(ptr, &value, sizeof(T));
  #endif /* __GNUC__ || __clang__ */
  #endif /* MDBX_UNALIGNED_OK */
  }
  
  } /* namespace unaligned */
  
  //-----------------------------------------------------------------------------
  
  #ifndef rot64
  static __inline uint64_t rot64(uint64_t v, unsigned s) {
    return (v >> s) | (v << (64 - s));
  }
  #endif /* rot64 */
  
  static __inline bool is_power2(size_t x) { return (x & (x - 1)) == 0; }
  
  #undef roundup2
  static __inline size_t roundup2(size_t value, size_t granularity) {
    assert(is_power2(granularity));
    return (value + granularity - 1) & ~(granularity - 1);
  }
  
  //-----------------------------------------------------------------------------
  
  static __inline void memory_barrier(void) {
  #if __has_extension(c_atomic) || __has_extension(cxx_atomic)
    __c11_atomic_thread_fence(__ATOMIC_SEQ_CST);
  #elif defined(__ATOMIC_SEQ_CST)
    __atomic_thread_fence(__ATOMIC_SEQ_CST);
  #elif defined(__clang__) || defined(__GNUC__)
    __sync_synchronize();
  #elif defined(_MSC_VER)
    MemoryBarrier();
  #elif defined(__INTEL_COMPILER) /* LY: Intel Compiler may mimic GCC and MSC */
  #if defined(__ia64__) || defined(__ia64) || defined(_M_IA64)
    __mf();
  #elif defined(__ia32__)
    _mm_mfence();
  #else
  #error "Unknown target for Intel Compiler, please report to us."
  #endif
  #elif defined(__SUNPRO_C) || defined(__sun) || defined(sun)
    __machine_rw_barrier();
  #elif (defined(_HPUX_SOURCE) || defined(__hpux) || defined(__HP_aCC)) &&       \
      (defined(HP_IA64) || defined(__ia64))
    _Asm_mf();
  #elif defined(_AIX) || defined(__ppc__) || defined(__powerpc__) ||             \
      defined(__ppc64__) || defined(__powerpc64__)
    __lwsync();
  #else
  #error "Could not guess the kind of compiler, please report to us."
  #endif
  }
  
  static __inline void cpu_relax() {
  #if defined(__ia32__)
    _mm_pause();
  #elif defined(_WIN32) || defined(_WIN64) || defined(_WINDOWS) ||               \
      defined(YieldProcessor)
    YieldProcessor();
  #else
  /* nope */
  #endif
  }
  
  //-----------------------------------------------------------------------------
  
  struct simple_checksum {
    uint64_t value;
  
    simple_checksum() : value(0) {}
  
    void push(const uint32_t &data) {
      value += data * UINT64_C(9386433910765580089) + 1;
      value ^= value >> 41;
      value *= UINT64_C(0xBD9CACC22C6E9571);
    }
  
    void push(const uint64_t &data) {
      push((uint32_t)data);
      push((uint32_t)(data >> 32));
    }
  
    void push(const bool data) {
      push(data ? UINT32_C(0x780E) : UINT32_C(0xFA18E));
    }
  
    void push(const void *ptr, size_t bytes) {
      const uint8_t *data = (const uint8_t *)ptr;
      for (size_t i = 0; i < bytes; ++i)
        push((uint32_t)data[i]);
    }
  
    void push(const double &data) { push(&data, sizeof(double)); }
    void push(const char *cstr) { push(cstr, strlen(cstr)); }
    void push(const std::string &str) { push(str.data(), str.size()); }
  
    void push(unsigned salt, const MDBX_val &val) {
      push(unsigned(val.iov_len));
      push(salt);
      push(val.iov_base, val.iov_len);
    }
  
  #if defined(_WIN32) || defined(_WIN64) || defined(_WINDOWS)
    void push(const HANDLE &handle) { push(&handle, sizeof(handle)); }
  #endif /* _WINDOWS */
  };
  
  std::string data2hex(const void *ptr, size_t bytes, simple_checksum &checksum);
  bool hex2data(const char *hex_begin, const char *hex_end, void *ptr,
                size_t bytes, simple_checksum &checksum);
  bool is_samedata(const MDBX_val *a, const MDBX_val *b);
  std::string format(const char *fmt, ...);
  
  uint64_t entropy_ticks(void);
  uint64_t entropy_white(void);
  static inline uint64_t bleach64(uint64_t v) {
    // Tommy Ettinger, https://www.blogger.com/profile/04953541827437796598
    // http://mostlymangling.blogspot.com/2019/01/better-stronger-mixer-and-test-procedure.html
    v ^= rot64(v, 25) ^ rot64(v, 50);
    v *= UINT64_C(0xA24BAED4963EE407);
    v ^= rot64(v, 24) ^ rot64(v, 49);
    v *= UINT64_C(0x9FB21C651E98DF25);
    return v ^ v >> 28;
  }
  
  static inline uint32_t bleach32(uint32_t x) {
    // https://github.com/skeeto/hash-prospector
    // exact bias: 0.17353355999581582
    x ^= x >> 16;
    x *= UINT32_C(0x7feb352d);
    x ^= 0x3027C563 ^ (x >> 15);
    x *= UINT32_C(0x846ca68b);
    x ^= x >> 16;
    return x;
  }
  
  static inline uint64_t prng64_map1_careless(uint64_t state) {
    return state * UINT64_C(6364136223846793005) + 1;
  }
  
  static inline uint64_t prng64_map2_careless(uint64_t state) {
    return (state + UINT64_C(1442695040888963407)) *
           UINT64_C(6364136223846793005);
  }
  
  static inline uint64_t prng64_map1_white(uint64_t state) {
    return bleach64(prng64_map1_careless(state));
  }
  
  static inline uint64_t prng64_map2_white(uint64_t state) {
    return bleach64(prng64_map2_careless(state));
  }
  
  static inline uint64_t prng64_careless(uint64_t &state) {
    state = prng64_map1_careless(state);
    return state;
  }
  
  static inline double u64_to_double1(uint64_t v) {
    union {
      uint64_t u64;
      double d;
    } casting;
  
    casting.u64 = UINT64_C(0x3ff) << 52 | (v >> 12);
    assert(casting.d >= 1.0 && casting.d < 2.0);
    return casting.d - 1.0;
  }
  
  uint64_t prng64_white(uint64_t &state);
  uint32_t prng32(uint64_t &state);
  void prng_fill(uint64_t &state, void *ptr, size_t bytes);
  
  void prng_seed(uint64_t seed);
  uint32_t prng32(void);
  uint64_t prng64(void);
  void prng_fill(void *ptr, size_t bytes);
  
  bool flipcoin();
  bool jitter(unsigned probability_percent);
  void jitter_delay(bool extra = false);
  