C++ cpp_int_backend::limbs方法代码示例

inline typename enable_if_c<
            is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value
            && is_signed_number<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value
            && boost::is_convertible<typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::local_limb_type, R>::value
         >::type
   eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& val)
{
   typedef typename common_type<R, typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::local_limb_type>::type common_type;
   if(std::numeric_limits<R>::is_specialized && (static_cast<common_type>(*val.limbs()) > static_cast<common_type>((std::numeric_limits<R>::max)())))
   {
      if(val.isneg())
      {
         if(static_cast<common_type>(*val.limbs()) > -static_cast<common_type>((std::numeric_limits<R>::min)()))
            conversion_overflow(typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::checked_type());
         *result = (std::numeric_limits<R>::min)();
      }
      else
      {
         conversion_overflow(typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::checked_type());
         *result = (std::numeric_limits<R>::max)();
      }
   }
   else
   {
      *result = static_cast<R>(*val.limbs());
      if(val.isneg())
      {
         check_is_negative(mpl::bool_<is_signed_number<R>::value || (number_category<R>::value == number_kind_floating_point)>());
         *result = negate_integer(*result, mpl::bool_<is_signed_number<R>::value || (number_category<R>::value == number_kind_floating_point)>());
      }
   }
}

inline typename enable_if_c<!is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value, unsigned>::type
   eval_lsb(const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& a)
{
   using default_ops::eval_get_sign;
   if(eval_get_sign(a) == 0)
   {
      BOOST_THROW_EXCEPTION(std::range_error("No bits were set in the operand."));
   }
   if(a.sign())
   {
      BOOST_THROW_EXCEPTION(std::range_error("Testing individual bits in negative values is not supported - results are undefined."));
   }

   //
   // Find the index of the least significant limb that is non-zero:
   //
   unsigned index = 0;
   while(!a.limbs()[index] && (index < a.size()))
      ++index;
   //
   // Find the index of the least significant bit within that limb:
   //
   unsigned result = boost::multiprecision::detail::find_lsb(a.limbs()[index]);

   return result + index * cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::limb_bits;
}

BOOST_MP_FORCEINLINE typename enable_if_c<
         is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value 
         && is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value
      >::type 
   eval_modulus(
      cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& result, 
      const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& o)
{
   if(!*o.limbs())
      BOOST_THROW_EXCEPTION(std::overflow_error("Division by zero."));
   *result.limbs() %= *o.limbs();
   result.sign(result.sign());
}

inline typename enable_if_c<
            is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value
            && is_unsigned_number<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value
         >::type
   eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& val)
{
   typedef typename common_type<R, typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::local_limb_type>::type common_type;
   if(std::numeric_limits<R>::is_specialized && (static_cast<common_type>(*val.limbs()) > static_cast<common_type>((std::numeric_limits<R>::max)())))
   {
      conversion_overflow(typename cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::checked_type());
      *result = (std::numeric_limits<R>::max)();
   }
   else
      *result = static_cast<R>(*val.limbs());
}

inline typename enable_if_c<!is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value>::type
   eval_gcd(
      cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& result,
      const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& a,
      const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& b)
{
   using default_ops::eval_lsb;
   using default_ops::eval_is_zero;
   using default_ops::eval_get_sign;

   if(a.size() == 1)
   {
      eval_gcd(result, b, *a.limbs());
      return;
   }
   if(b.size() == 1)
   {
      eval_gcd(result, a, *b.limbs());
      return;
   }

   int shift;

   cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> u(a), v(b);

   int s = eval_get_sign(u);

   /* GCD(0,x) := x */
   if(s < 0)
   {
      u.negate();
   }
   else if(s == 0)
   {
      result = v;
      return;
   }
   s = eval_get_sign(v);
   if(s < 0)
   {
      v.negate();
   }
   else if(s == 0)
   {
      result = u;
      return;
   }

   /* Let shift := lg K, where K is the greatest power of 2
   dividing both u and v. */

   unsigned us = eval_lsb(u);
   unsigned vs = eval_lsb(v);
   shift = (std::min)(us, vs);
   eval_right_shift(u, us);
   eval_right_shift(v, vs);

   do
   {
      /* Now u and v are both odd, so diff(u, v) is even.
      Let u = min(u, v), v = diff(u, v)/2. */
      s = u.compare(v);
      if(s > 0)
         u.swap(v);
      if(s == 0)
         break;
      if(v.size() <= 2)
      {
         if(v.size() == 1)
            u = integer_gcd_reduce(*v.limbs(), *u.limbs());
         else
         {
            double_limb_type i, j;
            i = v.limbs()[0] | (static_cast<double_limb_type>(v.limbs()[1]) << sizeof(limb_type) * CHAR_BIT);
            j = (u.size() == 1) ? *u.limbs() : u.limbs()[0] | (static_cast<double_limb_type>(u.limbs()[1]) << sizeof(limb_type) * CHAR_BIT);
            u = integer_gcd_reduce(i, j);
         }
         break;
      }
      eval_subtract(v, u);
      vs = eval_lsb(v);
      eval_right_shift(v, vs);
   }
   while(true);

   result = u;
   eval_left_shift(result, shift);
}

inline typename enable_if_c<!is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value, unsigned>::type
eval_msb_imp(const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& a)
{
   //
   // Find the index of the most significant bit that is non-zero:
   //
   return (a.size() - 1) * cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>::limb_bits + boost::multiprecision::detail::find_msb(a.limbs()[a.size() - 1]);
}