boost/multiprecision/detail/integer_ops.hpp
///////////////////////////////////////////////////////////////
// Copyright 2012 John Maddock. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_MP_INT_FUNC_HPP
#define BOOST_MP_INT_FUNC_HPP
#include <boost/multiprecision/number.hpp>
namespace boost { namespace multiprecision {
namespace default_ops {
template <class Backend>
inline BOOST_MP_CXX14_CONSTEXPR void eval_qr(const Backend& x, const Backend& y, Backend& q, Backend& r)
{
eval_divide(q, x, y);
eval_modulus(r, x, y);
}
template <class Backend, class Integer>
inline BOOST_MP_CXX14_CONSTEXPR Integer eval_integer_modulus(const Backend& x, Integer val)
{
BOOST_MP_USING_ABS
using default_ops::eval_convert_to;
using default_ops::eval_modulus;
typedef typename boost::multiprecision::detail::canonical<Integer, Backend>::type int_type;
Backend t;
eval_modulus(t, x, static_cast<int_type>(val));
Integer result(0);
eval_convert_to(&result, t);
return abs(result);
}
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable : 4127)
#endif
template <class B>
inline BOOST_MP_CXX14_CONSTEXPR void eval_gcd(B& result, const B& a, const B& b)
{
using default_ops::eval_get_sign;
using default_ops::eval_is_zero;
using default_ops::eval_lsb;
int shift(0);
B 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;
eval_subtract(v, u);
vs = eval_lsb(v);
eval_right_shift(v, vs);
} while (true);
result = u;
eval_left_shift(result, shift);
}
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
template <class B>
inline BOOST_MP_CXX14_CONSTEXPR void eval_lcm(B& result, const B& a, const B& b)
{
typedef typename mpl::front<typename B::unsigned_types>::type ui_type;
B t;
eval_gcd(t, a, b);
if (eval_is_zero(t))
{
result = static_cast<ui_type>(0);
}
else
{
eval_divide(result, a, t);
eval_multiply(result, b);
}
if (eval_get_sign(result) < 0)
result.negate();
}
} // namespace default_ops
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer>::type
divide_qr(const number<Backend, ExpressionTemplates>& x, const number<Backend, ExpressionTemplates>& y,
number<Backend, ExpressionTemplates>& q, number<Backend, ExpressionTemplates>& r)
{
using default_ops::eval_qr;
eval_qr(x.backend(), y.backend(), q.backend(), r.backend());
}
template <class Backend, expression_template_option ExpressionTemplates, class tag, class A1, class A2, class A3, class A4>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer>::type
divide_qr(const number<Backend, ExpressionTemplates>& x, const multiprecision::detail::expression<tag, A1, A2, A3, A4>& y,
number<Backend, ExpressionTemplates>& q, number<Backend, ExpressionTemplates>& r)
{
divide_qr(x, number<Backend, ExpressionTemplates>(y), q, r);
}
template <class tag, class A1, class A2, class A3, class A4, class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer>::type
divide_qr(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x, const number<Backend, ExpressionTemplates>& y,
number<Backend, ExpressionTemplates>& q, number<Backend, ExpressionTemplates>& r)
{
divide_qr(number<Backend, ExpressionTemplates>(x), y, q, r);
}
template <class tag, class A1, class A2, class A3, class A4, class tagb, class A1b, class A2b, class A3b, class A4b, class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer>::type
divide_qr(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x, const multiprecision::detail::expression<tagb, A1b, A2b, A3b, A4b>& y,
number<Backend, ExpressionTemplates>& q, number<Backend, ExpressionTemplates>& r)
{
divide_qr(number<Backend, ExpressionTemplates>(x), number<Backend, ExpressionTemplates>(y), q, r);
}
template <class Backend, expression_template_option ExpressionTemplates, class Integer>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if<mpl::and_<is_integral<Integer>, mpl::bool_<number_category<Backend>::value == number_kind_integer> >, Integer>::type
integer_modulus(const number<Backend, ExpressionTemplates>& x, Integer val)
{
using default_ops::eval_integer_modulus;
return eval_integer_modulus(x.backend(), val);
}
template <class tag, class A1, class A2, class A3, class A4, class Integer>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if<mpl::and_<is_integral<Integer>, mpl::bool_<number_category<typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type>::value == number_kind_integer> >, Integer>::type
integer_modulus(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x, Integer val)
{
typedef typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type result_type;
return integer_modulus(result_type(x), val);
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, unsigned>::type
lsb(const number<Backend, ExpressionTemplates>& x)
{
using default_ops::eval_lsb;
return eval_lsb(x.backend());
}
template <class tag, class A1, class A2, class A3, class A4>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type>::value == number_kind_integer, unsigned>::type
lsb(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x)
{
typedef typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type number_type;
number_type n(x);
using default_ops::eval_lsb;
return eval_lsb(n.backend());
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, unsigned>::type
msb(const number<Backend, ExpressionTemplates>& x)
{
using default_ops::eval_msb;
return eval_msb(x.backend());
}
template <class tag, class A1, class A2, class A3, class A4>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type>::value == number_kind_integer, unsigned>::type
msb(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x)
{
typedef typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type number_type;
number_type n(x);
using default_ops::eval_msb;
return eval_msb(n.backend());
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, bool>::type
bit_test(const number<Backend, ExpressionTemplates>& x, unsigned index)
{
using default_ops::eval_bit_test;
return eval_bit_test(x.backend(), index);
}
template <class tag, class A1, class A2, class A3, class A4>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type>::value == number_kind_integer, bool>::type
bit_test(const multiprecision::detail::expression<tag, A1, A2, A3, A4>& x, unsigned index)
{
typedef typename multiprecision::detail::expression<tag, A1, A2, A3, A4>::result_type number_type;
number_type n(x);
using default_ops::eval_bit_test;
return eval_bit_test(n.backend(), index);
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, number<Backend, ExpressionTemplates>&>::type
bit_set(number<Backend, ExpressionTemplates>& x, unsigned index)
{
using default_ops::eval_bit_set;
eval_bit_set(x.backend(), index);
return x;
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, number<Backend, ExpressionTemplates>&>::type
bit_unset(number<Backend, ExpressionTemplates>& x, unsigned index)
{
using default_ops::eval_bit_unset;
eval_bit_unset(x.backend(), index);
return x;
}
template <class Backend, expression_template_option ExpressionTemplates>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if_c<number_category<Backend>::value == number_kind_integer, number<Backend, ExpressionTemplates>&>::type
bit_flip(number<Backend, ExpressionTemplates>& x, unsigned index)
{
using default_ops::eval_bit_flip;
eval_bit_flip(x.backend(), index);
return x;
}
namespace default_ops {
//
// Within powm, we need a type with twice as many digits as the argument type, define
// a traits class to obtain that type:
//
template <class Backend>
struct double_precision_type
{
typedef Backend type;
};
//
// If the exponent is a signed integer type, then we need to
// check the value is positive:
//
template <class Backend>
inline BOOST_MP_CXX14_CONSTEXPR void check_sign_of_backend(const Backend& v, const mpl::true_)
{
if (eval_get_sign(v) < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("powm requires a positive exponent."));
}
}
template <class Backend>
inline BOOST_MP_CXX14_CONSTEXPR void check_sign_of_backend(const Backend&, const mpl::false_) {}
//
// Calculate (a^p)%c:
//
template <class Backend>
BOOST_MP_CXX14_CONSTEXPR void eval_powm(Backend& result, const Backend& a, const Backend& p, const Backend& c)
{
using default_ops::eval_bit_test;
using default_ops::eval_get_sign;
using default_ops::eval_modulus;
using default_ops::eval_multiply;
using default_ops::eval_right_shift;
typedef typename double_precision_type<Backend>::type double_type;
typedef typename boost::multiprecision::detail::canonical<unsigned char, double_type>::type ui_type;
check_sign_of_backend(p, mpl::bool_<std::numeric_limits<number<Backend> >::is_signed>());
double_type x, y(a), b(p), t;
x = ui_type(1u);
while (eval_get_sign(b) > 0)
{
if (eval_bit_test(b, 0))
{
eval_multiply(t, x, y);
eval_modulus(x, t, c);
}
eval_multiply(t, y, y);
eval_modulus(y, t, c);
eval_right_shift(b, ui_type(1));
}
Backend x2(x);
eval_modulus(result, x2, c);
}
template <class Backend, class Integer>
BOOST_MP_CXX14_CONSTEXPR void eval_powm(Backend& result, const Backend& a, const Backend& p, Integer c)
{
typedef typename double_precision_type<Backend>::type double_type;
typedef typename boost::multiprecision::detail::canonical<unsigned char, double_type>::type ui_type;
typedef typename boost::multiprecision::detail::canonical<Integer, double_type>::type i1_type;
typedef typename boost::multiprecision::detail::canonical<Integer, Backend>::type i2_type;
using default_ops::eval_bit_test;
using default_ops::eval_get_sign;
using default_ops::eval_modulus;
using default_ops::eval_multiply;
using default_ops::eval_right_shift;
check_sign_of_backend(p, mpl::bool_<std::numeric_limits<number<Backend> >::is_signed>());
if (eval_get_sign(p) < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("powm requires a positive exponent."));
}
double_type x, y(a), b(p), t;
x = ui_type(1u);
while (eval_get_sign(b) > 0)
{
if (eval_bit_test(b, 0))
{
eval_multiply(t, x, y);
eval_modulus(x, t, static_cast<i1_type>(c));
}
eval_multiply(t, y, y);
eval_modulus(y, t, static_cast<i1_type>(c));
eval_right_shift(b, ui_type(1));
}
Backend x2(x);
eval_modulus(result, x2, static_cast<i2_type>(c));
}
template <class Backend, class Integer>
BOOST_MP_CXX14_CONSTEXPR typename enable_if<is_unsigned<Integer> >::type eval_powm(Backend& result, const Backend& a, Integer b, const Backend& c)
{
typedef typename double_precision_type<Backend>::type double_type;
typedef typename boost::multiprecision::detail::canonical<unsigned char, double_type>::type ui_type;
using default_ops::eval_bit_test;
using default_ops::eval_get_sign;
using default_ops::eval_modulus;
using default_ops::eval_multiply;
using default_ops::eval_right_shift;
double_type x, y(a), t;
x = ui_type(1u);
while (b > 0)
{
if (b & 1)
{
eval_multiply(t, x, y);
eval_modulus(x, t, c);
}
eval_multiply(t, y, y);
eval_modulus(y, t, c);
b >>= 1;
}
Backend x2(x);
eval_modulus(result, x2, c);
}
template <class Backend, class Integer>
BOOST_MP_CXX14_CONSTEXPR typename enable_if<is_signed<Integer> >::type eval_powm(Backend& result, const Backend& a, Integer b, const Backend& c)
{
if (b < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("powm requires a positive exponent."));
}
eval_powm(result, a, static_cast<typename make_unsigned<Integer>::type>(b), c);
}
template <class Backend, class Integer1, class Integer2>
BOOST_MP_CXX14_CONSTEXPR typename enable_if<is_unsigned<Integer1> >::type eval_powm(Backend& result, const Backend& a, Integer1 b, Integer2 c)
{
typedef typename double_precision_type<Backend>::type double_type;
typedef typename boost::multiprecision::detail::canonical<unsigned char, double_type>::type ui_type;
typedef typename boost::multiprecision::detail::canonical<Integer1, double_type>::type i1_type;
typedef typename boost::multiprecision::detail::canonical<Integer2, Backend>::type i2_type;
using default_ops::eval_bit_test;
using default_ops::eval_get_sign;
using default_ops::eval_modulus;
using default_ops::eval_multiply;
using default_ops::eval_right_shift;
double_type x, y(a), t;
x = ui_type(1u);
while (b > 0)
{
if (b & 1)
{
eval_multiply(t, x, y);
eval_modulus(x, t, static_cast<i1_type>(c));
}
eval_multiply(t, y, y);
eval_modulus(y, t, static_cast<i1_type>(c));
b >>= 1;
}
Backend x2(x);
eval_modulus(result, x2, static_cast<i2_type>(c));
}
template <class Backend, class Integer1, class Integer2>
BOOST_MP_CXX14_CONSTEXPR typename enable_if<is_signed<Integer1> >::type eval_powm(Backend& result, const Backend& a, Integer1 b, Integer2 c)
{
if (b < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("powm requires a positive exponent."));
}
eval_powm(result, a, static_cast<typename make_unsigned<Integer1>::type>(b), c);
}
struct powm_func
{
template <class T, class U, class V>
BOOST_MP_CXX14_CONSTEXPR void operator()(T& result, const T& b, const U& p, const V& m) const
{
eval_powm(result, b, p, m);
}
};
} // namespace default_ops
template <class T, class U, class V>
inline BOOST_MP_CXX14_CONSTEXPR typename enable_if<
mpl::and_<
mpl::bool_<number_category<T>::value == number_kind_integer>,
mpl::or_<
is_number<T>,
is_number_expression<T> >,
mpl::or_<
is_number<U>,
is_number_expression<U>,
is_integral<U> >,
mpl::or_<
is_number<V>,
is_number_expression<V>,
is_integral<V> > >,
typename mpl::if_<
is_no_et_number<T>,
T,
typename mpl::if_<
is_no_et_number<U>,
U,
typename mpl::if_<
is_no_et_number<V>,
V,
detail::expression<detail::function, default_ops::powm_func, T, U, V> >::type>::type>::type>::type
powm(const T& b, const U& p, const V& mod)
{
return detail::expression<detail::function, default_ops::powm_func, T, U, V>(
default_ops::powm_func(), b, p, mod);
}
}} // namespace boost::multiprecision
#endif