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83 lines
2.9 KiB
C++
83 lines
2.9 KiB
C++
// boost integer.hpp header file -------------------------------------------//
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// (C) Copyright Beman Dawes 1999. Permission to copy, use, modify, sell
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// and distribute this software is granted provided this copyright
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// notice appears in all copies. This software is provided "as is" without
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// express or implied warranty, and with no claim as to its suitability for
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// any purpose.
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// See http://www.boost.org for most recent version including documentation.
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// Revision History
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// 30 Jul 00 Add typename syntax fix (Jens Maurer)
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// 28 Aug 99 Initial version
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#ifndef BOOST_INTEGER_HPP
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#define BOOST_INTEGER_HPP
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#include <limits>
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namespace boost
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{
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// Helper templates ------------------------------------------------------//
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// fast integers from least integers
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template< typename LeastInt >
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struct int_fast_t { typedef LeastInt fast; }; // imps may specialize
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// convert category to type
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template< int Category > struct int_least_helper {}; // default is empty
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// specializatons: 1=long, 2=int, 3=short, 4=signed char,
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// 6=unsigned long, 7=unsigned int, 8=unsigned short, 9=unsigned long
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// no specializations for 0 and 5: requests for a type > long are in error
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template<> struct int_least_helper<1> { typedef long least; };
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template<> struct int_least_helper<2> { typedef int least; };
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template<> struct int_least_helper<3> { typedef short least; };
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template<> struct int_least_helper<4> { typedef signed char least; };
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template<> struct int_least_helper<6> { typedef unsigned long least; };
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template<> struct int_least_helper<7> { typedef unsigned int least; };
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template<> struct int_least_helper<8> { typedef unsigned short least; };
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template<> struct int_least_helper<9> { typedef unsigned char least; };
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// integer templates specifying number of bits ---------------------------//
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// signed
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template< int Bits > // bits (including sign) required
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struct int_t
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{
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typedef typename int_least_helper
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<
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(Bits-1 <= std::numeric_limits<long>::digits) +
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(Bits-1 <= std::numeric_limits<int>::digits) +
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(Bits-1 <= std::numeric_limits<short>::digits) +
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(Bits-1 <= std::numeric_limits<signed char>::digits)
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>::least least;
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typedef typename int_fast_t<least>::fast fast;
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};
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// unsigned
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template< int Bits > // bits required
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struct uint_t
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{
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typedef typename int_least_helper
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<
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5 +
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(Bits <= std::numeric_limits<unsigned long>::digits) +
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(Bits <= std::numeric_limits<unsigned int>::digits) +
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(Bits <= std::numeric_limits<unsigned short>::digits) +
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(Bits <= std::numeric_limits<unsigned char>::digits)
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>::least least;
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typedef typename int_fast_t<least>::fast fast;
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};
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// The same dispatching technique can be used to select types based on
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// values. That will be added once boost::integer_traits is available.
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} // namespace boost
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#endif // BOOST_INTEGER_HPP
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