| |
| // Copyright 2012 John Maddock. Distributed under the Boost |
| // Software License, Version 1.0. (See accompanying file |
| // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_ |
| |
| #ifndef BOOST_MP_CPP_INT_CHECKED_HPP |
| #define BOOST_MP_CPP_INT_CHECKED_HPP |
| |
| namespace boost{ namespace multiprecision{ namespace backends{ namespace detail{ |
| |
| // |
| // Simple routines for performing checked arithmetic with a builtin arithmetic type. |
| // Note that this is not a complete header, it must be included as part of boost/multiprecision/cpp_int.hpp. |
| // |
| |
| inline void raise_overflow(std::string op) |
| { |
| BOOST_THROW_EXCEPTION(std::overflow_error("overflow in " + op)); |
| } |
| inline void raise_add_overflow() |
| { |
| raise_overflow("addition"); |
| } |
| inline void raise_subtract_overflow() |
| { |
| BOOST_THROW_EXCEPTION(std::range_error("Subtraction resulted in a negative value, but the type is unsigned")); |
| } |
| inline void raise_mul_overflow() |
| { |
| raise_overflow("multiplication"); |
| } |
| inline void raise_div_overflow() |
| { |
| raise_overflow("division"); |
| } |
| |
| template <class A> |
| inline A checked_add_imp(A a, A b, const mpl::true_&) |
| { |
| if(a > 0) |
| { |
| if((b > 0) && ((integer_traits<A>::const_max - b) < a)) |
| raise_add_overflow(); |
| } |
| else |
| { |
| if((b < 0) && ((integer_traits<A>::const_min - b) > a)) |
| raise_add_overflow(); |
| } |
| return a + b; |
| } |
| template <class A> |
| inline A checked_add_imp(A a, A b, const mpl::false_&) |
| { |
| if((integer_traits<A>::const_max - b) < a) |
| raise_add_overflow(); |
| return a + b; |
| } |
| template <class A> |
| inline A checked_add(A a, A b, const mpl::int_<checked>&) |
| { |
| return checked_add_imp(a, b, boost::is_signed<A>()); |
| } |
| template <class A> |
| inline A checked_add(A a, A b, const mpl::int_<unchecked>&) |
| { |
| return a + b; |
| } |
| |
| template <class A> |
| inline A checked_subtract_imp(A a, A b, const mpl::true_&) |
| { |
| if(a > 0) |
| { |
| if((b < 0) && ((integer_traits<A>::const_max + b) < a)) |
| raise_subtract_overflow(); |
| } |
| else |
| { |
| if((b > 0) && ((integer_traits<A>::const_min + b) > a)) |
| raise_subtract_overflow(); |
| } |
| return a - b; |
| } |
| template <class A> |
| inline A checked_subtract_imp(A a, A b, const mpl::false_&) |
| { |
| if(a < b) |
| raise_subtract_overflow(); |
| return a - b; |
| } |
| template <class A> |
| inline A checked_subtract(A a, A b, const mpl::int_<checked>&) |
| { |
| return checked_subtract_imp(a, b, boost::is_signed<A>()); |
| } |
| template <class A> |
| inline A checked_subtract(A a, A b, const mpl::int_<unchecked>&) |
| { |
| return a - b; |
| } |
| |
| template <class A> |
| inline A checked_multiply(A a, A b, const mpl::int_<checked>&) |
| { |
| BOOST_MP_USING_ABS |
| if(a && (integer_traits<A>::const_max / abs(a) < abs(b))) |
| raise_mul_overflow(); |
| return a * b; |
| } |
| template <class A> |
| inline A checked_multiply(A a, A b, const mpl::int_<unchecked>&) |
| { |
| return a * b; |
| } |
| |
| template <class A> |
| inline A checked_divide(A a, A b, const mpl::int_<checked>&) |
| { |
| if(b == 0) |
| raise_div_overflow(); |
| return a / b; |
| } |
| template <class A> |
| inline A checked_divide(A a, A b, const mpl::int_<unchecked>&) |
| { |
| return a / b; |
| } |
| |
| template <class A> |
| inline A checked_left_shift(A a, unsigned long long shift, const mpl::int_<checked>&) |
| { |
| if(a && shift) |
| { |
| if((shift > sizeof(A) * CHAR_BIT) || (a >> (sizeof(A) * CHAR_BIT - shift))) |
| BOOST_THROW_EXCEPTION(std::overflow_error("Shift out of range")); |
| } |
| return a << shift; |
| } |
| template <class A> |
| inline A checked_left_shift(A a, unsigned long long shift, const mpl::int_<unchecked>&) |
| { |
| return (shift >= sizeof(A) * CHAR_BIT) ? 0 : a << shift; |
| } |
| |
| }}}} // namespaces |
| |
| #endif |
| |