void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_floating_point>& /*to_type*/, const mpl::int_<number_kind_integer>& /*from_type*/)
{
using default_ops::eval_get_sign;
using default_ops::eval_bitwise_and;
using default_ops::eval_convert_to;
using default_ops::eval_right_shift;
using default_ops::eval_ldexp;
using default_ops::eval_add;
using default_ops::eval_is_zero;
// smallest unsigned type handled natively by "From" is likely to be it's limb_type:
typedef typename canonical<unsigned char, From>::type l_limb_type;
// get the corresponding type that we can assign to "To":
typedef typename canonical<l_limb_type, To>::type to_type;
From t(from);
bool is_neg = eval_get_sign(t) < 0;
if(is_neg)
t.negate();
// Pick off the first limb:
l_limb_type limb;
l_limb_type mask = static_cast<l_limb_type>(~static_cast<l_limb_type>(0));
From fl;
eval_bitwise_and(fl, t, mask);
eval_convert_to(&limb, fl);
to = static_cast<to_type>(limb);
eval_right_shift(t, std::numeric_limits<l_limb_type>::digits);
//
// Then keep picking off more limbs until "t" is zero:
//
To l;
unsigned shift = std::numeric_limits<l_limb_type>::digits;
while(!eval_is_zero(t))
{
eval_bitwise_and(fl, t, mask);
eval_convert_to(&limb, fl);
l = static_cast<to_type>(limb);
eval_right_shift(t, std::numeric_limits<l_limb_type>::digits);
eval_ldexp(l, l, shift);
eval_add(to, l);
shift += std::numeric_limits<l_limb_type>::digits;
}
//
// Finish off by setting the sign:
//
if(is_neg)
to.negate();
}
void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_floating_point>& /*to_type*/, const mpl::int_<number_kind_floating_point>& /*from_type*/)
{
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable:4127)
#endif
//
// The code here only works when the radix of "From" is 2, we could try shifting by other
// radixes but it would complicate things.... use a string conversion when the radix is other
// than 2:
//
if(std::numeric_limits<number<From> >::radix != 2)
{
to = from.str(0, std::ios_base::fmtflags()).c_str();
return;
}
typedef typename canonical<unsigned char, To>::type ui_type;
using default_ops::eval_fpclassify;
using default_ops::eval_add;
using default_ops::eval_subtract;
using default_ops::eval_convert_to;
//
// First classify the input, then handle the special cases:
//
int c = eval_fpclassify(from);
if(c == FP_ZERO)
{
to = ui_type(0);
return;
}
else if(c == FP_NAN)
{
to = "nan";
return;
}
else if(c == FP_INFINITE)
{
to = "inf";
if(eval_get_sign(from) < 0)
to.negate();
return;
}
typename From::exponent_type e;
From f, term;
to = ui_type(0);
eval_frexp(f, from, &e);
static const int shift = std::numeric_limits<boost::intmax_t>::digits - 1;
while(!eval_is_zero(f))
{
// extract int sized bits from f:
eval_ldexp(f, f, shift);
eval_floor(term, f);
e -= shift;
eval_ldexp(to, to, shift);
typename boost::multiprecision::detail::canonical<boost::intmax_t, To>::type ll;
eval_convert_to(&ll, term);
eval_add(to, ll);
eval_subtract(f, term);
}
typedef typename To::exponent_type to_exponent;
if((e > (std::numeric_limits<to_exponent>::max)()) || (e < (std::numeric_limits<to_exponent>::min)()))
{
to = "inf";
if(eval_get_sign(from) < 0)
to.negate();
return;
}
eval_ldexp(to, to, static_cast<to_exponent>(e));
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
}
