moved library

include/libtorrent/random_sample.hpp

@@ -0,0 +1,72 @@
+/*
+
+Copyright (c) 2006, Arvid Norberg & Daniel Wallin
+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.
+
+*/
+
+#ifndef TORRENT_RANDOM_SAMPLE_HPP
+#define TORRENT_RANDOM_SAMPLE_HPP
+
+#include <iterator>
+#include <cstdlib>
+
+namespace libtorrent
+{
+
+	template<class InIter, class OutIter, class Distance>
+	inline void random_sample_n(InIter start, InIter end
+			, OutIter out, Distance n)
+	{
+		Distance t = 0;
+		Distance m = 0;
+		Distance N = std::distance(start, end);
+
+		assert(N >= n);
+
+		while (m < n)
+		{
+			if ((rand() / (RAND_MAX + 1.f)) * (N - t) >= n - m)
+			{
+				++start;
+				++t;
+			}
+			else
+			{
+				*out = *start;
+				++out;
+				++start;
+				++t;
+				++m;
+			}
+		}
+	}
+
+}
+
+#endif