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diff --git a/src/sequence_number.h b/src/sequence_number.h
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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
+
+#include <cc++/config.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