text: #pragma once
  
  #include <Core/Types.h>
  #include <Common/BitHelpers.h>
  
  
  namespace DB
  {
  
  
  namespace UTF8
  {
  
  
  static const UInt8 CONTINUATION_OCTET_MASK = 0b11000000u;
  static const UInt8 CONTINUATION_OCTET = 0b10000000u;
  
  /// return true if `octet` binary repr starts with 10 (octet is a UTF-8 sequence continuation)
  inline bool isContinuationOctet(const UInt8 octet)
  {
      return (octet & CONTINUATION_OCTET_MASK) == CONTINUATION_OCTET;
  }
  
  /// moves `s` backward until either first non-continuation octet or begin
  inline void syncBackward(const UInt8 * & s, const UInt8 * const begin)
  {
      while (isContinuationOctet(*s) && s > begin)
          --s;
  }
  
  /// moves `s` forward until either first non-continuation octet or string end is met
  inline void syncForward(const UInt8 * & s, const UInt8 * const end)
  {
      while (s < end && isContinuationOctet(*s))
          ++s;
  }
  
  /// returns UTF-8 code point sequence length judging by it's first octet
  inline std::size_t seqLength(const UInt8 first_octet)
  {
      if (first_octet < 0x80u)
          return 1;
  
      const std::size_t bits = 8;
      const auto first_zero = bitScanReverse(static_cast<UInt8>(~first_octet));
  
      return bits - 1 - first_zero;
  }
  
  
  }
  
  
  }
  