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/*
Copyright (C) 2005-2009 Michel de Boer <michel@twinklephone.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file
* Sequence number operations.
*/
#ifndef _SEQUENCE_NUMBER_H
#define _SEQUENCE_NUMBER_H
/**
* Sequence numbers.
* Sequence numbers with comparison operators that deal with sequence number
* roll-overs using serial number arithmetic.
* See http://en.wikipedia.org/wiki/Serial_Number_Arithmetic
*
* @param U The unsigned int type for the sequence number.
* @param S The corresponsing signed int type having the same width.
*/
template< typename U, typename S >
class sequence_number_t {
private:
/**
* The sequence number.
*/
U _number;
public:
/**
* Constructor.
* @param number The sequence number.
*/
explicit sequence_number_t(U number) : _number(number)
{};
/**
* Get the sequence number.
* @return The sequence number.
*/
U get_number(void) const {
return _number;
}
/**
* Cast to the sequence number.
*/
operator U(void) const {
return get_number();
}
/**
* Calculate the distance to another sequence number.
* @param number The sequence number to which the distance must be calculated.
* @return The distance.
*/
S distance(const sequence_number_t &number) const {
return static_cast<S>(_number - number.get_number());
}
/**
* Calculate the distance to another distance sequence number.
* @param number The sequence number to which the distance must be calculated.
* @return The distance.
*/
S operator-(const sequence_number_t &number) const {
return distance(number);
}
/**
* Less-than comparison.
* @param number The sequence number to compare with.
* @return true, if this sequence number is less than number.
* @return false, otherwise.
*/
bool operator<(const sequence_number_t &number) const {
return (distance(number) < 0);
}
/**
* Less-than-equal comparison.
* @param number The sequence number to compare with.
* @return true, if this sequence number is less than or equal to number.
* @return false, otherwise.
*/
bool operator<=(const sequence_number_t &number) const {
return (distance(number) <= 0);
}
/**
* Equality comparison.
* @param number The sequence number to compare with.
* @return true, if this sequence number is equal to number.
* @return false, otherwise.
*/
bool operator==(const sequence_number_t &number) const {
return (number.get_number() == _number);
}
/**
* Greater-than comparison.
* @param number The sequence number to compare with.
* @return true, if this sequence number is greater than number.
* @return false, otherwise.
*/
bool operator>(const sequence_number_t &number) const {
return (distance(number) > 0);
}
/**
* Greater-than-equal comparison.
* @param number The sequence number to compare with.
* @return true, if this sequence number is greater than or equal to number.
* @return false, otherwise.
*/
bool operator>=(const sequence_number_t &number) const {
return (distance(number) >= 0);
}
};
/**
* 16-bit sequence number
*/
typedef sequence_number_t<uint16, int16> seq16_t;
/**
* 32-bit sequence number
*/
typedef sequence_number_t<uint32, int32> seq32_t;
#endif
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