Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: //  Copyright 2011 John Maddock. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_MP_GENERIC_INTERCONVERT_HPP
Chris@16: #define BOOST_MP_GENERIC_INTERCONVERT_HPP
Chris@16: 
Chris@16: #include <boost/multiprecision/detail/default_ops.hpp>
Chris@16: 
Chris@16: namespace boost{ namespace multiprecision{ namespace detail{
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: 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*/)
Chris@16: {
Chris@16:    using default_ops::eval_get_sign;
Chris@16:    using default_ops::eval_bitwise_and;
Chris@16:    using default_ops::eval_convert_to;
Chris@16:    using default_ops::eval_right_shift;
Chris@16:    using default_ops::eval_ldexp;
Chris@16:    using default_ops::eval_add;
Chris@16:    // smallest unsigned type handled natively by "From" is likely to be it's limb_type:
Chris@16:    typedef typename canonical<unsigned char, From>::type   limb_type;
Chris@16:    // get the corresponding type that we can assign to "To":
Chris@16:    typedef typename canonical<limb_type, To>::type         to_type;
Chris@16:    From t(from);
Chris@16:    bool is_neg = eval_get_sign(t) < 0;
Chris@16:    if(is_neg)
Chris@16:       t.negate();
Chris@16:    // Pick off the first limb:
Chris@16:    limb_type limb;
Chris@16:    limb_type mask = ~static_cast<limb_type>(0);
Chris@16:    From fl;
Chris@16:    eval_bitwise_and(fl, t, mask);
Chris@16:    eval_convert_to(&limb, fl);
Chris@16:    to = static_cast<to_type>(limb);
Chris@16:    eval_right_shift(t, std::numeric_limits<limb_type>::digits);
Chris@16:    //
Chris@16:    // Then keep picking off more limbs until "t" is zero:
Chris@16:    //
Chris@16:    To l;
Chris@16:    unsigned shift = std::numeric_limits<limb_type>::digits;
Chris@16:    while(!eval_is_zero(t))
Chris@16:    {
Chris@16:       eval_bitwise_and(fl, t, mask);
Chris@16:       eval_convert_to(&limb, fl);
Chris@16:       l = static_cast<to_type>(limb);
Chris@16:       eval_right_shift(t, std::numeric_limits<limb_type>::digits);
Chris@16:       eval_ldexp(l, l, shift);
Chris@16:       eval_add(to, l);
Chris@16:       shift += std::numeric_limits<limb_type>::digits;
Chris@16:    }
Chris@16:    //
Chris@16:    // Finish off by setting the sign:
Chris@16:    //
Chris@16:    if(is_neg)
Chris@16:       to.negate();
Chris@16: }
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_integer>& /*to_type*/, const mpl::int_<number_kind_integer>& /*from_type*/)
Chris@16: {
Chris@16:    using default_ops::eval_get_sign;
Chris@16:    using default_ops::eval_bitwise_and;
Chris@16:    using default_ops::eval_convert_to;
Chris@16:    using default_ops::eval_right_shift;
Chris@16:    using default_ops::eval_left_shift;
Chris@16:    using default_ops::eval_bitwise_or;
Chris@16:    using default_ops::eval_is_zero;
Chris@16:    // smallest unsigned type handled natively by "From" is likely to be it's limb_type:
Chris@16:    typedef typename canonical<unsigned char, From>::type   limb_type;
Chris@16:    // get the corresponding type that we can assign to "To":
Chris@16:    typedef typename canonical<limb_type, To>::type         to_type;
Chris@16:    From t(from);
Chris@16:    bool is_neg = eval_get_sign(t) < 0;
Chris@16:    if(is_neg)
Chris@16:       t.negate();
Chris@16:    // Pick off the first limb:
Chris@16:    limb_type limb;
Chris@16:    limb_type mask = static_cast<limb_type>(~static_cast<limb_type>(0));
Chris@16:    From fl;
Chris@16:    eval_bitwise_and(fl, t, mask);
Chris@16:    eval_convert_to(&limb, fl);
Chris@16:    to = static_cast<to_type>(limb);
Chris@16:    eval_right_shift(t, std::numeric_limits<limb_type>::digits);
Chris@16:    //
Chris@16:    // Then keep picking off more limbs until "t" is zero:
Chris@16:    //
Chris@16:    To l;
Chris@16:    unsigned shift = std::numeric_limits<limb_type>::digits;
Chris@16:    while(!eval_is_zero(t))
Chris@16:    {
Chris@16:       eval_bitwise_and(fl, t, mask);
Chris@16:       eval_convert_to(&limb, fl);
Chris@16:       l = static_cast<to_type>(limb);
Chris@16:       eval_right_shift(t, std::numeric_limits<limb_type>::digits);
Chris@16:       eval_left_shift(l, shift);
Chris@16:       eval_bitwise_or(to, l);
Chris@16:       shift += std::numeric_limits<limb_type>::digits;
Chris@16:    }
Chris@16:    //
Chris@16:    // Finish off by setting the sign:
Chris@16:    //
Chris@16:    if(is_neg)
Chris@16:       to.negate();
Chris@16: }
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: 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*/)
Chris@16: {
Chris@16: #ifdef BOOST_MSVC
Chris@16: #pragma warning(push)
Chris@16: #pragma warning(disable:4127)
Chris@16: #endif
Chris@16:    //
Chris@16:    // The code here only works when the radix of "From" is 2, we could try shifting by other
Chris@16:    // radixes but it would complicate things.... use a string conversion when the radix is other
Chris@16:    // than 2:
Chris@16:    //
Chris@16:    if(std::numeric_limits<number<From> >::radix != 2)
Chris@16:    {
Chris@16:       to = from.str(0, std::ios_base::fmtflags()).c_str();
Chris@16:       return;
Chris@16:    }
Chris@16: 
Chris@16: 
Chris@16:    typedef typename canonical<unsigned char, To>::type ui_type;
Chris@16: 
Chris@16:    using default_ops::eval_fpclassify;
Chris@16:    using default_ops::eval_add;
Chris@16:    using default_ops::eval_subtract;
Chris@16:    using default_ops::eval_convert_to;
Chris@16: 
Chris@16:    //
Chris@16:    // First classify the input, then handle the special cases:
Chris@16:    //
Chris@16:    int c = eval_fpclassify(from);
Chris@16: 
Chris@16:    if(c == FP_ZERO) 
Chris@16:    {
Chris@16:       to = ui_type(0);
Chris@16:       return;
Chris@16:    }
Chris@16:    else if(c == FP_NAN)
Chris@16:    {
Chris@16:       to = "nan";
Chris@16:       return;
Chris@16:    }
Chris@16:    else if(c == FP_INFINITE)
Chris@16:    {
Chris@16:       to = "inf";
Chris@16:       if(eval_get_sign(from) < 0)
Chris@16:          to.negate();
Chris@16:       return;
Chris@16:    }
Chris@16: 
Chris@16:    typename From::exponent_type e;
Chris@16:    From f, term;
Chris@16:    to = ui_type(0);
Chris@16: 
Chris@16:    eval_frexp(f, from, &e);
Chris@16: 
Chris@16:    static const int shift = std::numeric_limits<boost::intmax_t>::digits - 1;
Chris@16: 
Chris@16:    while(!eval_is_zero(f))
Chris@16:    {
Chris@16:       // extract int sized bits from f:
Chris@16:       eval_ldexp(f, f, shift);
Chris@16:       eval_floor(term, f);
Chris@16:       e -= shift;
Chris@16:       eval_ldexp(to, to, shift);
Chris@16:       typename boost::multiprecision::detail::canonical<boost::intmax_t, To>::type ll;
Chris@16:       eval_convert_to(&ll, term);
Chris@16:       eval_add(to, ll);
Chris@16:       eval_subtract(f, term);
Chris@16:    }
Chris@16:    typedef typename To::exponent_type to_exponent;
Chris@16:    if((e > (std::numeric_limits<to_exponent>::max)()) || (e < (std::numeric_limits<to_exponent>::min)()))
Chris@16:    {
Chris@16:       to = "inf";
Chris@16:       if(eval_get_sign(from) < 0)
Chris@16:          to.negate();
Chris@16:       return;
Chris@16:    }
Chris@16:    eval_ldexp(to, to, static_cast<to_exponent>(e));
Chris@16: #ifdef BOOST_MSVC
Chris@16: #pragma warning(pop)
Chris@16: #endif
Chris@16: }
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_rational>& /*to_type*/, const mpl::int_<number_kind_rational>& /*from_type*/)
Chris@16: {
Chris@16:    typedef typename component_type<number<To> >::type     to_component_type;
Chris@16: 
Chris@16:    number<From> t(from);
Chris@16:    to_component_type n(numerator(t)), d(denominator(t));
Chris@16:    using default_ops::assign_components;
Chris@16:    assign_components(to, n.backend(), d.backend());
Chris@16: }
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_rational>& /*to_type*/, const mpl::int_<number_kind_integer>& /*from_type*/)
Chris@16: {
Chris@16:    typedef typename component_type<number<To> >::type     to_component_type;
Chris@16: 
Chris@16:    number<From> t(from);
Chris@16:    to_component_type n(t), d(1);
Chris@16:    using default_ops::assign_components;
Chris@16:    assign_components(to, n.backend(), d.backend());
Chris@16: }
Chris@16: 
Chris@16: template <class To, class From>
Chris@16: void generic_interconvert(To& to, const From& from, const mpl::int_<number_kind_floating_point>& /*to_type*/, const mpl::int_<number_kind_rational>& /*from_type*/)
Chris@16: {
Chris@16:    typedef typename component_type<number<From> >::type   from_component_type;
Chris@16:    using default_ops::eval_divide;
Chris@16: 
Chris@16:    number<From> t(from);
Chris@16:    from_component_type n(numerator(t)), d(denominator(t));
Chris@16:    number<To> fn(n), fd(d);
Chris@16:    eval_divide(to, fn.backend(), fd.backend());
Chris@16: }
Chris@16: 
Chris@16: }}} // namespaces
Chris@16: 
Chris@16: #endif  // BOOST_MP_GENERIC_INTERCONVERT_HPP
Chris@16: