text: #ifndef _BRYNET_BASE_BASE64_H
  #define _BRYNET_BASE_BASE64_H
  
  #include <string>
  
  namespace bsio::base::crypto {
  
  static const std::string base64_chars =
          "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
          "abcdefghijklmnopqrstuvwxyz"
          "0123456789+/";
  
  static bool is_base64(unsigned char c)
  {
      return (isalnum(c) || (c == '+') || (c == '/'));
  }
  
  static std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len)
  {
      std::string ret;
      int i = 0;
      int j = 0;
      unsigned char char_array_3[3];
      unsigned char char_array_4[4];
  
      while (in_len--)
      {
          char_array_3[i++] = *(bytes_to_encode++);
          if (i == 3)
          {
              char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
              char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
              char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
              char_array_4[3] = char_array_3[2] & 0x3f;
  
              for (i = 0; (i < 4); i++)
                  ret += base64_chars[char_array_4[i]];
              i = 0;
          }
      }
  
      if (i)
      {
          for (j = i; j < 3; j++)
              char_array_3[j] = '\0';
  
          char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
          char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
          char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
          char_array_4[3] = char_array_3[2] & 0x3f;
  
          for (j = 0; (j < i + 1); j++)
              ret += base64_chars[char_array_4[j]];
  
          while ((i++ < 3))
              ret += '=';
      }
  
      return ret;
  }
  
  static std::string base64_decode(std::string const& encoded_string)
  {
      int in_len = encoded_string.size();
      int i = 0;
      int j = 0;
      int in_ = 0;
      unsigned char char_array_4[4], char_array_3[3];
      std::string ret;
  
      while (in_len-- && (encoded_string[in_] != '=') && is_base64(encoded_string[in_]))
      {
          char_array_4[i++] = encoded_string[in_];
          in_++;
          if (i == 4)
          {
              for (i = 0; i < 4; i++)
                  char_array_4[i] = base64_chars.find(char_array_4[i]);
  
              char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
              char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
              char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
  
              for (i = 0; (i < 3); i++)
                  ret += char_array_3[i];
              i = 0;
          }
      }
  
      if (i)
      {
          for (j = i; j < 4; j++)
              char_array_4[j] = 0;
  
          for (j = 0; j < 4; j++)
              char_array_4[j] = base64_chars.find(char_array_4[j]);
  
          char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
          char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
          char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
  
          for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
      }
  
      return ret;
  }
  
  }// namespace bsio::base::crypto
  
  #endif
  