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libtins/include/small_uint.h

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2.5 KiB
C++

/*
* libtins is a net packet wrapper library for crafting and
* interpreting sniffed packets.
*
* Copyright (C) 2011 Nasel
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef TINS_SMALL_UINT_H
#define TINS_SMALL_UINT_H
#include <stdint.h>
#include <stdexcept>
namespace Tins {
template<size_t n>
class small_uint {
private:
template<bool cond, typename OnTrue, typename OnFalse>
struct if_then_else {
typedef OnTrue type;
};
template<typename OnTrue, typename OnFalse>
struct if_then_else<false, OnTrue, OnFalse> {
typedef OnFalse type;
};
template<size_t i>
struct best_type {
typedef typename if_then_else<
(i <= 8),
uint8_t,
typename if_then_else<
(i <= 16),
uint16_t,
typename if_then_else<
(i <= 32),
uint32_t,
uint64_t
>::type
>::type
>::type type;
};
template<uint64_t base, uint64_t pow>
struct power {
static const uint64_t value = base * power<base, pow - 1>::value;
};
template<uint64_t base>
struct power<base, 0> {
static const uint64_t value = 1;
};
public:
class value_to_large : public std::exception {
public:
const char *what() const throw() {
return "Value is too large";
}
};
typedef typename best_type<n>::type repr_type;
static const repr_type max_value = power<2, n>::value - 1;
small_uint() : value() {}
small_uint(repr_type val) {
if(val > max_value)
throw value_to_large();
value = val;
}
operator repr_type() const {
return value;
}
private:
repr_type value;
};
} // namespace Tins
#endif // TINS_SMALL_UINT_H