text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2014 The Bitcoin developers
  // Copyright (c) 2014-2015 The Dash developers
  // Copyright (c) 2015-2017 The PIVX developers
  // Copyright (c) 2017 The Midori developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_UINT256_H
  #define BITCOIN_UINT256_H
  
  #include <assert.h>
  #include <cstring>
  #include <stdexcept>
  #include <stdint.h>
  #include <string>
  #include <vector>
  
  class uint_error : public std::runtime_error
  {
  public:
      explicit uint_error(const std::string& str) : std::runtime_error(str) {}
  };
  
  /** Template base class for unsigned big integers. */
  template <unsigned int BITS>
  class base_uint
  {
  protected:
      enum { WIDTH = BITS / 32 };
      uint32_t pn[WIDTH];
  
  public:
      base_uint()
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      base_uint(const base_uint& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
      }
  
  
      bool IsNull() const
      {
          for (int i = 0; i < WIDTH; i++)
              if (pn[i] != 0)
                  return false;
          return true;
      }
  
      void SetNull()
      {
          memset(pn, 0, sizeof(pn));
      }
  
  
      base_uint& operator=(const base_uint& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
          return *this;
      }
  
      base_uint(uint64_t b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      explicit base_uint(const std::string& str);
      explicit base_uint(const std::vector<unsigned char>& vch);
  
      bool operator!() const
      {
          for (int i = 0; i < WIDTH; i++)
              if (pn[i] != 0)
                  return false;
          return true;
      }
  
      const base_uint operator~() const
      {
          base_uint ret;
          for (int i = 0; i < WIDTH; i++)
              ret.pn[i] = ~pn[i];
          return ret;
      }
  
      const base_uint operator-() const
      {
          base_uint ret;
          for (int i = 0; i < WIDTH; i++)
              ret.pn[i] = ~pn[i];
          ret++;
          return ret;
      }
  
      double getdouble() const;
  
      base_uint& operator=(uint64_t b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
          return *this;
      }
  
      base_uint& operator^=(const base_uint& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] ^= b.pn[i];
          return *this;
      }
  
      base_uint& operator&=(const base_uint& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] &= b.pn[i];
          return *this;
      }
  
      base_uint& operator|=(const base_uint& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] |= b.pn[i];
          return *this;
      }
  
      base_uint& operator^=(uint64_t b)
      {
          pn[0] ^= (unsigned int)b;
          pn[1] ^= (unsigned int)(b >> 32);
          return *this;
      }
  
      base_uint& operator|=(uint64_t b)
      {
          pn[0] |= (unsigned int)b;
          pn[1] |= (unsigned int)(b >> 32);
          return *this;
      }
  
      base_uint& operator<<=(unsigned int shift);
      base_uint& operator>>=(unsigned int shift);
  
      base_uint& operator+=(const base_uint& b)
      {
          uint64_t carry = 0;
          for (int i = 0; i < WIDTH; i++) {
              uint64_t n = carry + pn[i] + b.pn[i];
              pn[i] = n & 0xffffffff;
              carry = n >> 32;
          }
          return *this;
      }
  
      base_uint& operator-=(const base_uint& b)
      {
          *this += -b;
          return *this;
      }
  
      base_uint& operator+=(uint64_t b64)
      {
          base_uint b;
          b = b64;
          *this += b;
          return *this;
      }
  
      base_uint& operator-=(uint64_t b64)
      {
          base_uint b;
          b = b64;
          *this += -b;
          return *this;
      }
  
      base_uint& operator*=(uint32_t b32);
      base_uint& operator*=(const base_uint& b);
      base_uint& operator/=(const base_uint& b);
  
      base_uint& operator++()
      {
          // prefix operator
          int i = 0;
          while (++pn[i] == 0 && i < WIDTH - 1)
              i++;
          return *this;
      }
  
      const base_uint operator++(int)
      {
          // postfix operator
          const base_uint ret = *this;
          ++(*this);
          return ret;
      }
  
      base_uint& operator--()
      {
          // prefix operator
          int i = 0;
          while (--pn[i] == (uint32_t)-1 && i < WIDTH - 1)
              i++;
          return *this;
      }
  
      const base_uint operator--(int)
      {
          // postfix operator
          const base_uint ret = *this;
          --(*this);
          return ret;
      }
  
      int CompareTo(const base_uint& b) const;
      bool EqualTo(uint64_t b) const;
  
      friend inline const base_uint operator+(const base_uint& a, const base_uint& b) { return base_uint(a) += b; }
      friend inline const base_uint operator-(const base_uint& a, const base_uint& b) { return base_uint(a) -= b; }
      friend inline const base_uint operator*(const base_uint& a, const base_uint& b) { return base_uint(a) *= b; }
      friend inline const base_uint operator/(const base_uint& a, const base_uint& b) { return base_uint(a) /= b; }
      friend inline const base_uint operator|(const base_uint& a, const base_uint& b) { return base_uint(a) |= b; }
      friend inline const base_uint operator&(const base_uint& a, const base_uint& b) { return base_uint(a) &= b; }
      friend inline const base_uint operator^(const base_uint& a, const base_uint& b) { return base_uint(a) ^= b; }
      friend inline const base_uint operator>>(const base_uint& a, int shift) { return base_uint(a) >>= shift; }
      friend inline const base_uint operator<<(const base_uint& a, int shift) { return base_uint(a) <<= shift; }
      friend inline const base_uint operator*(const base_uint& a, uint32_t b) { return base_uint(a) *= b; }
      friend inline bool operator==(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) == 0; }
      friend inline bool operator!=(const base_uint& a, const base_uint& b) { return memcmp(a.pn, b.pn, sizeof(a.pn)) != 0; }
      friend inline bool operator>(const base_uint& a, const base_uint& b) { return a.CompareTo(b) > 0; }
      friend inline bool operator<(const base_uint& a, const base_uint& b) { return a.CompareTo(b) < 0; }
      friend inline bool operator>=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) >= 0; }
      friend inline bool operator<=(const base_uint& a, const base_uint& b) { return a.CompareTo(b) <= 0; }
      friend inline bool operator==(const base_uint& a, uint64_t b) { return a.EqualTo(b); }
      friend inline bool operator!=(const base_uint& a, uint64_t b) { return !a.EqualTo(b); }
  
      std::string GetHex() const;
      void SetHex(const char* psz);
      void SetHex(const std::string& str);
      std::string ToString() const;
      std::string ToStringReverseEndian() const;
  
      unsigned char* begin()
      {
          return (unsigned char*)&pn[0];
      }
  
      unsigned char* end()
      {
          return (unsigned char*)&pn[WIDTH];
      }
  
      const unsigned char* begin() const
      {
          return (unsigned char*)&pn[0];
      }
  
      const unsigned char* end() const
      {
          return (unsigned char*)&pn[WIDTH];
      }
  
      unsigned int size() const
      {
          return sizeof(pn);
      }
  
      uint64_t Get64(int n = 0) const
      {
          return pn[2 * n] | (uint64_t)pn[2 * n + 1] << 32;
      }
  
      uint32_t Get32(int n = 0) const
      {
          return pn[2 * n];
      }
      /**
       * Returns the position of the highest bit set plus one, or zero if the
       * value is zero.
       */
      unsigned int bits() const;
  
      uint64_t GetLow64() const
      {
          assert(WIDTH >= 2);
          return pn[0] | (uint64_t)pn[1] << 32;
      }
  
      unsigned int GetSerializeSize(int nType, int nVersion) const
      {
          return sizeof(pn);
      }
  
      template <typename Stream>
      void Serialize(Stream& s, int nType, int nVersion) const
      {
          s.write((char*)pn, sizeof(pn));
      }
  
      template <typename Stream>
      void Unserialize(Stream& s, int nType, int nVersion)
      {
          s.read((char*)pn, sizeof(pn));
      }
  
      friend class uint160;
      friend class uint256;
      friend class uint512;
  };
  
  /** 160-bit unsigned big integer. */
  class uint160 : public base_uint<160>
  {
  public:
      uint160() {}
      uint160(const base_uint<160>& b) : base_uint<160>(b) {}
      uint160(uint64_t b) : base_uint<160>(b) {}
      explicit uint160(const std::string& str) : base_uint<160>(str) {}
      explicit uint160(const std::vector<unsigned char>& vch) : base_uint<160>(vch) {}
  };
  
  /** 256-bit unsigned big integer. */
  class uint256 : public base_uint<256>
  {
  public:
      uint256() {}
      uint256(const base_uint<256>& b) : base_uint<256>(b) {}
      uint256(uint64_t b) : base_uint<256>(b) {}
      explicit uint256(const std::string& str) : base_uint<256>(str) {}
      explicit uint256(const std::vector<unsigned char>& vch) : base_uint<256>(vch) {}
  
      /**
       * The "compact" format is a representation of a whole
       * number N using an unsigned 32bit number similar to a
       * floating point format.
       * The most significant 8 bits are the unsigned exponent of base 256.
       * This exponent can be thought of as "number of bytes of N".
       * The lower 23 bits are the mantissa.
       * Bit number 24 (0x800000) represents the sign of N.
       * N = (-1^sign) * mantissa * 256^(exponent-3)
       * 
       * Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn().
       * MPI uses the most significant bit of the first byte as sign.
       * Thus 0x1234560000 is compact (0x05123456)
       * and  0xc0de000000 is compact (0x0600c0de)
       * 
       * Bitcoin only uses this "compact" format for encoding difficulty
       * targets, which are unsigned 256bit quantities.  Thus, all the
       * complexities of the sign bit and using base 256 are probably an
       * implementation accident.
       */
      uint256& SetCompact(uint32_t nCompact, bool* pfNegative = NULL, bool* pfOverflow = NULL);
      uint32_t GetCompact(bool fNegative = false) const;
      uint64_t GetHash(const uint256& salt) const;
  };
  
  /* uint256 from const char *.
   * This is a separate function because the constructor uint256(const char*) can result
   * in dangerously catching uint256(0).
   */
  inline uint256 uint256S(const char* str)
  {
      uint256 rv;
      rv.SetHex(str);
      return rv;
  }
  /* uint256 from std::string.
   * This is a separate function because the constructor uint256(const std::string &str) can result
   * in dangerously catching uint256(0) via std::string(const char*).
   */
  inline uint256 uint256S(const std::string& str)
  {
      uint256 rv;
      rv.SetHex(str);
      return rv;
  }
  
  /** 512-bit unsigned big integer. */
  class uint512 : public base_uint<512>
  {
  public:
      uint512() {}
      uint512(const base_uint<512>& b) : base_uint<512>(b) {}
      uint512(uint64_t b) : base_uint<512>(b) {}
      explicit uint512(const std::string& str) : base_uint<512>(str) {}
      explicit uint512(const std::vector<unsigned char>& vch) : base_uint<512>(vch) {}
  
      uint256 trim256() const
      {
          uint256 ret;
          for (unsigned int i = 0; i < uint256::WIDTH; i++) {
              ret.pn[i] = pn[i];
          }
          return ret;
      }
  };
  
  inline uint512 uint512S(const std::string& str)
  {
      uint512 rv;
      rv.SetHex(str);
      return rv;
  }
  
  #endif // BITCOIN_UINT256_H
  