text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2015 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  /**
   * Utilities for converting data from/to strings.
   */
  #ifndef BITCOIN_UTILSTRENCODINGS_H
  #define BITCOIN_UTILSTRENCODINGS_H
  
  #include <stdint.h>
  #include <string>
  #include <vector>
  #include "serialize.h"
  #include "allocators.h"
  
  
  #include <boost/date_time/posix_time/posix_time.hpp>
  #include <openssl/bio.h>
  #include <openssl/evp.h>
  #include <openssl/buffer.h>
  #include <openssl/crypto.h> // for OPENSSL_cleanse()
  #include <openssl/rand.h>
  #include <openssl/bn.h>
  
  
  #define BEGIN(a)            ((char*)&(a))
  #define END(a)              ((char*)&((&(a))[1]))
  #define UBEGIN(a)           ((unsigned char*)&(a))
  #define UEND(a)             ((unsigned char*)&((&(a))[1]))
  #define ARRAYLEN(array)     (sizeof(array)/sizeof((array)[0]))
  
  /** This is needed because the foreach macro can't get over the comma in pair<t1, t2> */
  #define PAIRTYPE(t1, t2)    std::pair<t1, t2>
  
  
  
  std::vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid = NULL);
  std::string DecodeBase64(const std::string& str);
  std::string EncodeBase64(const unsigned char* pch, size_t len);
  std::string EncodeBase64(const std::string& str);
  SecureString DecodeBase64Secure(const SecureString& input);
  SecureString EncodeBase64Secure(const SecureString& input);
  std::vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid = NULL);
  std::string DecodeBase32(const std::string& str);
  std::string EncodeBase32(const unsigned char* pch, size_t len);
  std::string EncodeBase32(const std::string& str);
  
  
  std::string i64tostr(int64_t n);
  std::string itostr(int n);
  int64_t atoi64(const char* psz);
  int64_t atoi64(const std::string& str);
  int atoi(const std::string& str);
  
  /**
   * Convert string to signed 32-bit integer with strict parse error feedback.
   * @returns true if the entire string could be parsed as valid integer,
   *   false if not the entire string could be parsed or when overflow or underflow occurred.
   */
  bool ParseInt32(const std::string& str, int32_t *out);
  
  template<typename T>
  std::string HexStr(const T itbegin, const T itend, bool fSpaces=false)
  {
      std::string rv;
      static const char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
                                       '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
      rv.reserve((itend-itbegin)*3);
      for(T it = itbegin; it < itend; ++it)
      {
          unsigned char val = (unsigned char)(*it);
          if(fSpaces && it != itbegin)
              rv.push_back(' ');
          rv.push_back(hexmap[val>>4]);
          rv.push_back(hexmap[val&15]);
      }
  
      return rv;
  }
  
  template<typename T>
  inline std::string HexStr(const T& vch, bool fSpaces=false)
  {
      return HexStr(vch.begin(), vch.end(), fSpaces);
  }
  
  /** 
   * Format a paragraph of text to a fixed width, adding spaces for
   * indentation to any added line.
   */
  std::string FormatParagraph(const std::string in, size_t width=79, size_t indent=0);
  
  /**
   * Timing-attack-resistant comparison.
   * Takes time proportional to length
   * of first argument.
   */
  template <typename T>
  bool TimingResistantEqual(const T& a, const T& b)
  {
      if (b.size() == 0) return a.size() == 0;
      size_t accumulator = a.size() ^ b.size();
      for (size_t i = 0; i < a.size(); i++)
          accumulator |= a[i] ^ b[i%b.size()];
      return accumulator == 0;
  }
  
  #endif // BITCOIN_UTILSTRENCODINGS_H
  