text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2012 The Bitcoin developers
  // Copyright (c) 2011-2012 Litecoin Developers
  // Copyright (c) 2013 Dogecoin Developers
  // Copyright (c) 2014 Corgicoin Developers
  // Distributed under the MIT/X11 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 <limits.h>
  #include <stdio.h>
  #include <string.h>
  #include <string>
  #include <vector>
  
  typedef long long  int64;
  typedef unsigned long long  uint64;
  
  
  inline int Testuint256AdHoc(std::vector<std::string> vArg);
  
  
  
  /** Base class without constructors for uint256 and uint160.
   * This makes the compiler let u use it in a union.
   */
  template<unsigned int BITS>
  class base_uint
  {
  protected:
      enum { WIDTH=BITS/32 };
      unsigned int pn[WIDTH];
  public:
  
      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;
      }
  
  
      base_uint& operator=(uint64 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 b)
      {
          pn[0] ^= (unsigned int)b;
          pn[1] ^= (unsigned int)(b >> 32);
          return *this;
      }
  
      base_uint& operator|=(uint64 b)
      {
          pn[0] |= (unsigned int)b;
          pn[1] |= (unsigned int)(b >> 32);
          return *this;
      }
  
      base_uint& operator<<=(unsigned int shift)
      {
          base_uint a(*this);
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
          int k = shift / 32;
          shift = shift % 32;
          for (int i = 0; i < WIDTH; i++)
          {
              if (i+k+1 < WIDTH && shift != 0)
                  pn[i+k+1] |= (a.pn[i] >> (32-shift));
              if (i+k < WIDTH)
                  pn[i+k] |= (a.pn[i] << shift);
          }
          return *this;
      }
  
      base_uint& operator>>=(unsigned int shift)
      {
          base_uint a(*this);
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
          int k = shift / 32;
          shift = shift % 32;
          for (int i = 0; i < WIDTH; i++)
          {
              if (i-k-1 >= 0 && shift != 0)
                  pn[i-k-1] |= (a.pn[i] << (32-shift));
              if (i-k >= 0)
                  pn[i-k] |= (a.pn[i] >> shift);
          }
          return *this;
      }
  
      base_uint& operator+=(const base_uint& b)
      {
          uint64 carry = 0;
          for (int i = 0; i < WIDTH; i++)
          {
              uint64 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 b64)
      {
          base_uint b;
          b = b64;
          *this += b;
          return *this;
      }
  
      base_uint& operator-=(uint64 b64)
      {
          base_uint b;
          b = b64;
          *this += -b;
          return *this;
      }
  
  
      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] == -1 && i < WIDTH-1)
              i++;
          return *this;
      }
  
      const base_uint operator--(int)
      {
          // postfix operator
          const base_uint ret = *this;
          --(*this);
          return ret;
      }
  
  
      friend inline bool operator<(const base_uint& a, const base_uint& b)
      {
          for (int i = base_uint::WIDTH-1; i >= 0; i--)
          {
              if (a.pn[i] < b.pn[i])
                  return true;
              else if (a.pn[i] > b.pn[i])
                  return false;
          }
          return false;
      }
  
      friend inline bool operator<=(const base_uint& a, const base_uint& b)
      {
          for (int i = base_uint::WIDTH-1; i >= 0; i--)
          {
              if (a.pn[i] < b.pn[i])
                  return true;
              else if (a.pn[i] > b.pn[i])
                  return false;
          }
          return true;
      }
  
      friend inline bool operator>(const base_uint& a, const base_uint& b)
      {
          for (int i = base_uint::WIDTH-1; i >= 0; i--)
          {
              if (a.pn[i] > b.pn[i])
                  return true;
              else if (a.pn[i] < b.pn[i])
                  return false;
          }
          return false;
      }
  
      friend inline bool operator>=(const base_uint& a, const base_uint& b)
      {
          for (int i = base_uint::WIDTH-1; i >= 0; i--)
          {
              if (a.pn[i] > b.pn[i])
                  return true;
              else if (a.pn[i] < b.pn[i])
                  return false;
          }
          return true;
      }
  
      friend inline bool operator==(const base_uint& a, const base_uint& b)
      {
          for (int i = 0; i < base_uint::WIDTH; i++)
              if (a.pn[i] != b.pn[i])
                  return false;
          return true;
      }
  
      friend inline bool operator==(const base_uint& a, uint64 b)
      {
          if (a.pn[0] != (unsigned int)b)
              return false;
          if (a.pn[1] != (unsigned int)(b >> 32))
              return false;
          for (int i = 2; i < base_uint::WIDTH; i++)
              if (a.pn[i] != 0)
                  return false;
          return true;
      }
  
      friend inline bool operator!=(const base_uint& a, const base_uint& b)
      {
          return (!(a == b));
      }
  
      friend inline bool operator!=(const base_uint& a, uint64 b)
      {
          return (!(a == b));
      }
  
  
  
      std::string GetHex() const
      {
          char psz[sizeof(pn)*2 + 1];
          for (unsigned int i = 0; i < sizeof(pn); i++)
              sprintf(psz + i*2, "%02x", ((unsigned char*)pn)[sizeof(pn) - i - 1]);
          return std::string(psz, psz + sizeof(pn)*2);
      }
  
      void SetHex(const char* psz)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
  
          // skip leading spaces
          while (isspace(*psz))
              psz++;
  
          // skip 0x
          if (psz[0] == '0' && tolower(psz[1]) == 'x')
              psz += 2;
  
          // hex string to uint
          static unsigned char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
          const char* pbegin = psz;
          while (phexdigit[(unsigned char)*psz] || *psz == '0')
              psz++;
          psz--;
          unsigned char* p1 = (unsigned char*)pn;
          unsigned char* pend = p1 + WIDTH * 4;
          while (psz >= pbegin && p1 < pend)
          {
              *p1 = phexdigit[(unsigned char)*psz--];
              if (psz >= pbegin)
              {
                  *p1 |= (phexdigit[(unsigned char)*psz--] << 4);
                  p1++;
              }
          }
      }
  
      void SetHex(const std::string& str)
      {
          SetHex(str.c_str());
      }
  
      std::string ToString() const
      {
          return (GetHex());
      }
  
      unsigned char* begin()
      {
          return (unsigned char*)&pn[0];
      }
  
      unsigned char* end()
      {
          return (unsigned char*)&pn[WIDTH];
      }
  
      unsigned int size()
      {
          return sizeof(pn);
      }
  
      uint64 Get64(int n=0) const
      {
          return pn[2*n] | (uint64)pn[2*n+1] << 32;
      }
  
  //    unsigned int GetSerializeSize(int nType=0, int nVersion=PROTOCOL_VERSION) const
      unsigned int GetSerializeSize(int nType, int nVersion) const
      {
          return sizeof(pn);
      }
  
      template<typename Stream>
  //    void Serialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION) const
      void Serialize(Stream& s, int nType, int nVersion) const
      {
          s.write((char*)pn, sizeof(pn));
      }
  
      template<typename Stream>
  //    void Unserialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION)
      void Unserialize(Stream& s, int nType, int nVersion)
      {
          s.read((char*)pn, sizeof(pn));
      }
  
  
      friend class uint160;
      friend class uint256;
      friend inline int Testuint256AdHoc(std::vector<std::string> vArg);
  };
  
  typedef base_uint<160> base_uint160;
  typedef base_uint<256> base_uint256;
  
  
  
  //
  // uint160 and uint256 could be implemented as templates, but to keep
  // compile errors and debugging cleaner, they're copy and pasted.
  //
  
  
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // uint160
  //
  
  /** 160-bit unsigned integer */
  class uint160 : public base_uint160
  {
  public:
      typedef base_uint160 basetype;
  
      uint160()
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      uint160(const basetype& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
      }
  
      uint160& operator=(const basetype& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
          return *this;
      }
  
      uint160(uint64 b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      uint160& operator=(uint64 b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
          return *this;
      }
  
      explicit uint160(const std::string& str)
      {
          SetHex(str);
      }
  
      explicit uint160(const std::vector<unsigned char>& vch)
      {
          if (vch.size() == sizeof(pn))
              memcpy(pn, &vch[0], sizeof(pn));
          else
              *this = 0;
      }
  };
  
  inline bool operator==(const uint160& a, uint64 b)                           { return (base_uint160)a == b; }
  inline bool operator!=(const uint160& a, uint64 b)                           { return (base_uint160)a != b; }
  inline const uint160 operator<<(const base_uint160& a, unsigned int shift)   { return uint160(a) <<= shift; }
  inline const uint160 operator>>(const base_uint160& a, unsigned int shift)   { return uint160(a) >>= shift; }
  inline const uint160 operator<<(const uint160& a, unsigned int shift)        { return uint160(a) <<= shift; }
  inline const uint160 operator>>(const uint160& a, unsigned int shift)        { return uint160(a) >>= shift; }
  
  inline const uint160 operator^(const base_uint160& a, const base_uint160& b) { return uint160(a) ^= b; }
  inline const uint160 operator&(const base_uint160& a, const base_uint160& b) { return uint160(a) &= b; }
  inline const uint160 operator|(const base_uint160& a, const base_uint160& b) { return uint160(a) |= b; }
  inline const uint160 operator+(const base_uint160& a, const base_uint160& b) { return uint160(a) += b; }
  inline const uint160 operator-(const base_uint160& a, const base_uint160& b) { return uint160(a) -= b; }
  
  inline bool operator<(const base_uint160& a, const uint160& b)          { return (base_uint160)a <  (base_uint160)b; }
  inline bool operator<=(const base_uint160& a, const uint160& b)         { return (base_uint160)a <= (base_uint160)b; }
  inline bool operator>(const base_uint160& a, const uint160& b)          { return (base_uint160)a >  (base_uint160)b; }
  inline bool operator>=(const base_uint160& a, const uint160& b)         { return (base_uint160)a >= (base_uint160)b; }
  inline bool operator==(const base_uint160& a, const uint160& b)         { return (base_uint160)a == (base_uint160)b; }
  inline bool operator!=(const base_uint160& a, const uint160& b)         { return (base_uint160)a != (base_uint160)b; }
  inline const uint160 operator^(const base_uint160& a, const uint160& b) { return (base_uint160)a ^  (base_uint160)b; }
  inline const uint160 operator&(const base_uint160& a, const uint160& b) { return (base_uint160)a &  (base_uint160)b; }
  inline const uint160 operator|(const base_uint160& a, const uint160& b) { return (base_uint160)a |  (base_uint160)b; }
  inline const uint160 operator+(const base_uint160& a, const uint160& b) { return (base_uint160)a +  (base_uint160)b; }
  inline const uint160 operator-(const base_uint160& a, const uint160& b) { return (base_uint160)a -  (base_uint160)b; }
  
  inline bool operator<(const uint160& a, const base_uint160& b)          { return (base_uint160)a <  (base_uint160)b; }
  inline bool operator<=(const uint160& a, const base_uint160& b)         { return (base_uint160)a <= (base_uint160)b; }
  inline bool operator>(const uint160& a, const base_uint160& b)          { return (base_uint160)a >  (base_uint160)b; }
  inline bool operator>=(const uint160& a, const base_uint160& b)         { return (base_uint160)a >= (base_uint160)b; }
  inline bool operator==(const uint160& a, const base_uint160& b)         { return (base_uint160)a == (base_uint160)b; }
  inline bool operator!=(const uint160& a, const base_uint160& b)         { return (base_uint160)a != (base_uint160)b; }
  inline const uint160 operator^(const uint160& a, const base_uint160& b) { return (base_uint160)a ^  (base_uint160)b; }
  inline const uint160 operator&(const uint160& a, const base_uint160& b) { return (base_uint160)a &  (base_uint160)b; }
  inline const uint160 operator|(const uint160& a, const base_uint160& b) { return (base_uint160)a |  (base_uint160)b; }
  inline const uint160 operator+(const uint160& a, const base_uint160& b) { return (base_uint160)a +  (base_uint160)b; }
  inline const uint160 operator-(const uint160& a, const base_uint160& b) { return (base_uint160)a -  (base_uint160)b; }
  
  inline bool operator<(const uint160& a, const uint160& b)               { return (base_uint160)a <  (base_uint160)b; }
  inline bool operator<=(const uint160& a, const uint160& b)              { return (base_uint160)a <= (base_uint160)b; }
  inline bool operator>(const uint160& a, const uint160& b)               { return (base_uint160)a >  (base_uint160)b; }
  inline bool operator>=(const uint160& a, const uint160& b)              { return (base_uint160)a >= (base_uint160)b; }
  inline bool operator==(const uint160& a, const uint160& b)              { return (base_uint160)a == (base_uint160)b; }
  inline bool operator!=(const uint160& a, const uint160& b)              { return (base_uint160)a != (base_uint160)b; }
  inline const uint160 operator^(const uint160& a, const uint160& b)      { return (base_uint160)a ^  (base_uint160)b; }
  inline const uint160 operator&(const uint160& a, const uint160& b)      { return (base_uint160)a &  (base_uint160)b; }
  inline const uint160 operator|(const uint160& a, const uint160& b)      { return (base_uint160)a |  (base_uint160)b; }
  inline const uint160 operator+(const uint160& a, const uint160& b)      { return (base_uint160)a +  (base_uint160)b; }
  inline const uint160 operator-(const uint160& a, const uint160& b)      { return (base_uint160)a -  (base_uint160)b; }
  
  
  
  
  
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // uint256
  //
  
  /** 256-bit unsigned integer */
  class uint256 : public base_uint256
  {
  public:
      typedef base_uint256 basetype;
  
      uint256()
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      uint256(const basetype& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
      }
  
      uint256& operator=(const basetype& b)
      {
          for (int i = 0; i < WIDTH; i++)
              pn[i] = b.pn[i];
          return *this;
      }
  
      uint256(uint64 b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
      }
  
      uint256& operator=(uint64 b)
      {
          pn[0] = (unsigned int)b;
          pn[1] = (unsigned int)(b >> 32);
          for (int i = 2; i < WIDTH; i++)
              pn[i] = 0;
          return *this;
      }
  
      explicit uint256(const std::string& str)
      {
          SetHex(str);
      }
  
      explicit uint256(const std::vector<unsigned char>& vch)
      {
          if (vch.size() == sizeof(pn))
              memcpy(pn, &vch[0], sizeof(pn));
          else
              *this = 0;
      }
  };
  
  inline bool operator==(const uint256& a, uint64 b)                           { return (base_uint256)a == b; }
  inline bool operator!=(const uint256& a, uint64 b)                           { return (base_uint256)a != b; }
  inline const uint256 operator<<(const base_uint256& a, unsigned int shift)   { return uint256(a) <<= shift; }
  inline const uint256 operator>>(const base_uint256& a, unsigned int shift)   { return uint256(a) >>= shift; }
  inline const uint256 operator<<(const uint256& a, unsigned int shift)        { return uint256(a) <<= shift; }
  inline const uint256 operator>>(const uint256& a, unsigned int shift)        { return uint256(a) >>= shift; }
  
  inline const uint256 operator^(const base_uint256& a, const base_uint256& b) { return uint256(a) ^= b; }
  inline const uint256 operator&(const base_uint256& a, const base_uint256& b) { return uint256(a) &= b; }
  inline const uint256 operator|(const base_uint256& a, const base_uint256& b) { return uint256(a) |= b; }
  inline const uint256 operator+(const base_uint256& a, const base_uint256& b) { return uint256(a) += b; }
  inline const uint256 operator-(const base_uint256& a, const base_uint256& b) { return uint256(a) -= b; }
  
  inline bool operator<(const base_uint256& a, const uint256& b)          { return (base_uint256)a <  (base_uint256)b; }
  inline bool operator<=(const base_uint256& a, const uint256& b)         { return (base_uint256)a <= (base_uint256)b; }
  inline bool operator>(const base_uint256& a, const uint256& b)          { return (base_uint256)a >  (base_uint256)b; }
  inline bool operator>=(const base_uint256& a, const uint256& b)         { return (base_uint256)a >= (base_uint256)b; }
  inline bool operator==(const base_uint256& a, const uint256& b)         { return (base_uint256)a == (base_uint256)b; }
  inline bool operator!=(const base_uint256& a, const uint256& b)         { return (base_uint256)a != (base_uint256)b; }
  inline const uint256 operator^(const base_uint256& a, const uint256& b) { return (base_uint256)a ^  (base_uint256)b; }
  inline const uint256 operator&(const base_uint256& a, const uint256& b) { return (base_uint256)a &  (base_uint256)b; }
  inline const uint256 operator|(const base_uint256& a, const uint256& b) { return (base_uint256)a |  (base_uint256)b; }
  inline const uint256 operator+(const base_uint256& a, const uint256& b) { return (base_uint256)a +  (base_uint256)b; }
  inline const uint256 operator-(const base_uint256& a, const uint256& b) { return (base_uint256)a -  (base_uint256)b; }
  
  inline bool operator<(const uint256& a, const base_uint256& b)          { return (base_uint256)a <  (base_uint256)b; }
  inline bool operator<=(const uint256& a, const base_uint256& b)         { return (base_uint256)a <= (base_uint256)b; }
  inline bool operator>(const uint256& a, const base_uint256& b)          { return (base_uint256)a >  (base_uint256)b; }
  inline bool operator>=(const uint256& a, const base_uint256& b)         { return (base_uint256)a >= (base_uint256)b; }
  inline bool operator==(const uint256& a, const base_uint256& b)         { return (base_uint256)a == (base_uint256)b; }
  inline bool operator!=(const uint256& a, const base_uint256& b)         { return (base_uint256)a != (base_uint256)b; }
  inline const uint256 operator^(const uint256& a, const base_uint256& b) { return (base_uint256)a ^  (base_uint256)b; }
  inline const uint256 operator&(const uint256& a, const base_uint256& b) { return (base_uint256)a &  (base_uint256)b; }
  inline const uint256 operator|(const uint256& a, const base_uint256& b) { return (base_uint256)a |  (base_uint256)b; }
  inline const uint256 operator+(const uint256& a, const base_uint256& b) { return (base_uint256)a +  (base_uint256)b; }
  inline const uint256 operator-(const uint256& a, const base_uint256& b) { return (base_uint256)a -  (base_uint256)b; }
  
  inline bool operator<(const uint256& a, const uint256& b)               { return (base_uint256)a <  (base_uint256)b; }
  inline bool operator<=(const uint256& a, const uint256& b)              { return (base_uint256)a <= (base_uint256)b; }
  inline bool operator>(const uint256& a, const uint256& b)               { return (base_uint256)a >  (base_uint256)b; }
  inline bool operator>=(const uint256& a, const uint256& b)              { return (base_uint256)a >= (base_uint256)b; }
  inline bool operator==(const uint256& a, const uint256& b)              { return (base_uint256)a == (base_uint256)b; }
  inline bool operator!=(const uint256& a, const uint256& b)              { return (base_uint256)a != (base_uint256)b; }
  inline const uint256 operator^(const uint256& a, const uint256& b)      { return (base_uint256)a ^  (base_uint256)b; }
  inline const uint256 operator&(const uint256& a, const uint256& b)      { return (base_uint256)a &  (base_uint256)b; }
  inline const uint256 operator|(const uint256& a, const uint256& b)      { return (base_uint256)a |  (base_uint256)b; }
  inline const uint256 operator+(const uint256& a, const uint256& b)      { return (base_uint256)a +  (base_uint256)b; }
  inline const uint256 operator-(const uint256& a, const uint256& b)      { return (base_uint256)a -  (base_uint256)b; }
  
  
  
  
  
  
  
  
  
  
  #ifdef TEST_UINT256
  
  inline int Testuint256AdHoc(std::vector<std::string> vArg)
  {
      uint256 g(0);
  
  
      printf("%s\n", g.ToString().c_str());
      g--;  printf("g--\n");
      printf("%s\n", g.ToString().c_str());
      g--;  printf("g--\n");
      printf("%s\n", g.ToString().c_str());
      g++;  printf("g++\n");
      printf("%s\n", g.ToString().c_str());
      g++;  printf("g++\n");
      printf("%s\n", g.ToString().c_str());
      g++;  printf("g++\n");
      printf("%s\n", g.ToString().c_str());
      g++;  printf("g++\n");
      printf("%s\n", g.ToString().c_str());
  
  
  
      uint256 a(7);
      printf("a=7\n");
      printf("%s\n", a.ToString().c_str());
  
      uint256 b;
      printf("b undefined\n");
      printf("%s\n", b.ToString().c_str());
      int c = 3;
  
      a = c;
      a.pn[3] = 15;
      printf("%s\n", a.ToString().c_str());
      uint256 k(c);
  
      a = 5;
      a.pn[3] = 15;
      printf("%s\n", a.ToString().c_str());
      b = 1;
      b <<= 52;
  
      a |= b;
  
      a ^= 0x500;
  
      printf("a %s\n", a.ToString().c_str());
  
      a = a | b | (uint256)0x1000;
  
  
      printf("a %s\n", a.ToString().c_str());
      printf("b %s\n", b.ToString().c_str());
  
      a = 0xfffffffe;
      a.pn[4] = 9;
  
      printf("%s\n", a.ToString().c_str());
      a++;
      printf("%s\n", a.ToString().c_str());
      a++;
      printf("%s\n", a.ToString().c_str());
      a++;
      printf("%s\n", a.ToString().c_str());
      a++;
      printf("%s\n", a.ToString().c_str());
  
      a--;
      printf("%s\n", a.ToString().c_str());
      a--;
      printf("%s\n", a.ToString().c_str());
      a--;
      printf("%s\n", a.ToString().c_str());
      uint256 d = a--;
      printf("%s\n", d.ToString().c_str());
      printf("%s\n", a.ToString().c_str());
      a--;
      printf("%s\n", a.ToString().c_str());
      a--;
      printf("%s\n", a.ToString().c_str());
  
      d = a;
  
      printf("%s\n", d.ToString().c_str());
      for (int i = uint256::WIDTH-1; i >= 0; i--) printf("%08x", d.pn[i]); printf("\n");
  
      uint256 neg = d;
      neg = ~neg;
      printf("%s\n", neg.ToString().c_str());
  
  
      uint256 e = uint256("0xABCDEF123abcdef12345678909832180000011111111");
      printf("\n");
      printf("%s\n", e.ToString().c_str());
  
  
      printf("\n");
      uint256 x1 = uint256("0xABCDEF123abcdef12345678909832180000011111111");
      uint256 x2;
      printf("%s\n", x1.ToString().c_str());
      for (int i = 0; i < 270; i += 4)
      {
          x2 = x1 << i;
          printf("%s\n", x2.ToString().c_str());
      }
  
      printf("\n");
      printf("%s\n", x1.ToString().c_str());
      for (int i = 0; i < 270; i += 4)
      {
          x2 = x1;
          x2 >>= i;
          printf("%s\n", x2.ToString().c_str());
      }
  
  
      for (int i = 0; i < 100; i++)
      {
          uint256 k = (~uint256(0) >> i);
          printf("%s\n", k.ToString().c_str());
      }
  
      for (int i = 0; i < 100; i++)
      {
          uint256 k = (~uint256(0) << i);
          printf("%s\n", k.ToString().c_str());
      }
  
      return (0);
  }
  
  #endif
  
  #endif
  