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+/* <!-- copyright */
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+/*
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+ * aria2 - The high speed download utility
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+ *
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+ * Copyright (C) 2009 Tatsuhiro Tsujikawa
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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+ *
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+ * In addition, as a special exception, the copyright holders give
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+ * permission to link the code of portions of this program with the
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+ * OpenSSL library under certain conditions as described in each
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+ * individual source file, and distribute linked combinations
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+ * including the two.
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+ * You must obey the GNU General Public License in all respects
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+ * for all of the code used other than OpenSSL. If you modify
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+ * file(s) with this exception, you may extend this exception to your
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+ * version of the file(s), but you are not obligated to do so. If you
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+ * do not wish to do so, delete this exception statement from your
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+ * version. If you delete this exception statement from all source
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+ * files in the program, then also delete it here.
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+ */
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+/* copyright --> */
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+#ifndef _D_BITFIELD_H_
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+#define _D_BITFIELD_H_
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+
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+#include "common.h"
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+
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+#include <cassert>
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+#include <cstdlib>
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+
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+#include "Util.h"
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+
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+namespace aria2 {
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+
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+namespace bitfield {
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+
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+// Returns the bit mask for the last byte. For example, nbits = 9,
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+// then 0x80 is returned. nbits = 12, then 0xf0 is returned.
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+inline unsigned char lastByteMask(size_t nbits)
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+{
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+ return -256 >> (8-((nbits+7)/8*8-nbits));
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+}
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+
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+// Returns true if index-th bits is set. Otherwise returns false.
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+inline bool test(const unsigned char* bitfield, size_t nbits, size_t index)
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+{
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+ assert(index < nbits);
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+ unsigned char mask = 128 >> (index%8);
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+ return (bitfield[index/8]&mask) != 0;
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+}
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+
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+inline size_t countBit32(uint32_t n)
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+{
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+ static const int nbits[] = {
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+ 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
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+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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+ 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
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+ };
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+ return
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+ nbits[n&0xffu]+
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+ nbits[(n >> 8)&0xffu]+
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+ nbits[(n >> 16)&0xffu]+
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+ nbits[(n >> 24)&0xffu];
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+}
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+
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+// Counts set bit in bitfield.
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+inline size_t countSetBit(const unsigned char* bitfield, size_t nbits)
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+{
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+ size_t count = 0;
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+ size_t size = sizeof(uint32_t);
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+ size_t len = (nbits+7)/8;
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+ size_t to = len/size;
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+ for(size_t i = 0; i < to; ++i) {
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+ count += countBit32(*reinterpret_cast<const uint32_t*>(&bitfield[i*size]));
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+ }
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+ for(size_t i = len-len%size; i < len-1; ++i) {
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+ count += countBit32(static_cast<uint32_t>(bitfield[i]));
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+ }
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+ if(nbits%32 != 0) {
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+ count +=
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+ countBit32(static_cast<uint32_t>(bitfield[len-1]&lastByteMask(nbits)));
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+ }
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+ return count;
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+}
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+
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+} // namespace bitfield
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+
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+} // namespace aria2
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+
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+#endif // _D_BITFIELD_H_
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