merged uTP branch into trunk (yay)

src/timestamp_history.cpp

@@ -0,0 +1,105 @@
+/*
+
+Copyright (c) 2009, Arvid Norberg
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in
+      the documentation and/or other materials provided with the distribution.
+    * Neither the name of the author nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+
+#include "libtorrent/timestamp_history.hpp"
+
+namespace libtorrent {
+
+enum
+{
+	TIME_MASK = 0xffffffff
+};
+// defined in utp_stream.cpp
+bool compare_less_wrap(boost::uint32_t lhs, boost::uint32_t rhs
+	, boost::uint32_t mask);
+
+boost::uint32_t timestamp_history::add_sample(boost::uint32_t sample, bool step)
+{
+	if (!m_initialized)
+	{
+		for (int i = 0; i < history_size; ++i)
+			m_history[i] = sample;
+		m_base = sample;
+		m_initialized = true;
+	}
+
+	++m_num_samples;
+
+	// if sample is less than base, update the base
+	// and update the history entry (because it will
+	// be less than that too)
+	if (compare_less_wrap(sample, m_base, TIME_MASK))
+	{
+		m_base = sample;
+		m_history[m_index] = sample;
+	}
+	// if sample is less than our history entry, update it
+	else if (compare_less_wrap(sample, m_history[m_index], TIME_MASK))
+	{
+		m_history[m_index] = sample;
+	}
+
+	boost::uint32_t ret = sample - m_base;
+
+	// don't step base delay history unless we have at least 120
+	// samples. Anything less would suggest that the connection is
+	// essentially idle and the samples are probably not very reliable
+	if (step && m_num_samples > 120)
+	{
+		m_num_samples = 0;
+		m_index = (m_index + 1) % history_size;
+
+		m_history[m_index] = sample;
+		// update m_base
+		m_base = sample;
+		for (int i = 0; i < history_size; ++i)
+		{
+			if (compare_less_wrap(m_history[i], m_base, TIME_MASK))
+				m_base = m_history[i];
+		}
+	}
+	return ret;
+}
+
+void timestamp_history::adjust_base(int change)
+{
+	m_base += change;
+	// make sure this adjustment sticks by updating all history slots
+	for (int i = 0; i < history_size; ++i)
+	{
+		if (compare_less_wrap(m_history[i], m_base, TIME_MASK))
+			m_history[i] = m_base;
+	}
+}
+
+}