149 lines
4.4 KiB
C++
149 lines
4.4 KiB
C++
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// Copyright 2012 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
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#ifndef BOOST_MP_CPP_INT_CHECKED_HPP
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#define BOOST_MP_CPP_INT_CHECKED_HPP
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namespace boost { namespace multiprecision { namespace backends { namespace detail {
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//
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// Simple routines for performing checked arithmetic with a builtin arithmetic type.
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// Note that this is not a complete header, it must be included as part of boost/multiprecision/cpp_int.hpp.
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//
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inline void raise_overflow(std::string op)
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{
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BOOST_THROW_EXCEPTION(std::overflow_error("overflow in " + op));
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}
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inline void raise_add_overflow()
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{
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raise_overflow("addition");
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}
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inline void raise_subtract_overflow()
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{
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BOOST_THROW_EXCEPTION(std::range_error("Subtraction resulted in a negative value, but the type is unsigned"));
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}
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inline void raise_mul_overflow()
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{
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raise_overflow("multiplication");
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}
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inline void raise_div_overflow()
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{
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raise_overflow("division");
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_add_imp(A a, A b, const std::integral_constant<bool, true>&)
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{
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if (a > 0)
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{
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if ((b > 0) && ((integer_traits<A>::const_max - b) < a))
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raise_add_overflow();
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}
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else
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{
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if ((b < 0) && ((integer_traits<A>::const_min - b) > a))
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raise_add_overflow();
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}
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return a + b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_add_imp(A a, A b, const std::integral_constant<bool, false>&)
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{
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if ((integer_traits<A>::const_max - b) < a)
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raise_add_overflow();
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return a + b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_add(A a, A b, const std::integral_constant<int, checked>&)
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{
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return checked_add_imp(a, b, std::integral_constant<bool, boost::multiprecision::detail::is_signed<A>::value && boost::multiprecision::detail::is_integral<A>::value > ());
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_add(A a, A b, const std::integral_constant<int, unchecked>&)
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{
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return a + b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_subtract_imp(A a, A b, const std::integral_constant<bool, true>&)
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{
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if (a > 0)
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{
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if ((b < 0) && ((integer_traits<A>::const_max + b) < a))
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raise_subtract_overflow();
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}
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else
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{
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if ((b > 0) && ((integer_traits<A>::const_min + b) > a))
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raise_subtract_overflow();
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}
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return a - b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_subtract_imp(A a, A b, const std::integral_constant<bool, false>&)
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{
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if (a < b)
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raise_subtract_overflow();
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return a - b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_subtract(A a, A b, const std::integral_constant<int, checked>&)
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{
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return checked_subtract_imp(a, b, std::integral_constant<bool, boost::multiprecision::detail::is_signed<A>::value && boost::multiprecision::detail::is_integral<A>::value>());
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_subtract(A a, A b, const std::integral_constant<int, unchecked>&)
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{
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return a - b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_multiply(A a, A b, const std::integral_constant<int, checked>&)
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{
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BOOST_MP_USING_ABS
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if (a && (integer_traits<A>::const_max / abs(a) < abs(b)))
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raise_mul_overflow();
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return a * b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_multiply(A a, A b, const std::integral_constant<int, unchecked>&)
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{
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return a * b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_divide(A a, A b, const std::integral_constant<int, checked>&)
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{
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if (b == 0)
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raise_div_overflow();
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return a / b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_divide(A a, A b, const std::integral_constant<int, unchecked>&)
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{
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return a / b;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_left_shift(A a, boost::ulong_long_type shift, const std::integral_constant<int, checked>&)
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{
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if (a && shift)
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{
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if ((shift > sizeof(A) * CHAR_BIT) || (a >> (sizeof(A) * CHAR_BIT - shift)))
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BOOST_THROW_EXCEPTION(std::overflow_error("Shift out of range"));
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}
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return a << shift;
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}
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template <class A>
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inline BOOST_MP_CXX14_CONSTEXPR A checked_left_shift(A a, boost::ulong_long_type shift, const std::integral_constant<int, unchecked>&)
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{
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return (shift >= sizeof(A) * CHAR_BIT) ? 0 : a << shift;
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}
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}}}} // namespace boost::multiprecision::backends::detail
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#endif
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