mirror of https://gitee.com/bigwinds/arangodb
75 lines
1.9 KiB
C++
75 lines
1.9 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Jan Steemann
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/// @author http://en.wikipedia.org/wiki/Binary_GCD_algorithm
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_BASICS_GCD_H
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#define ARANGODB_BASICS_GCD_H 1
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#include "Basics/Common.h"
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namespace arangodb {
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namespace basics {
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////////////////////////////////////////////////////////////////////////////////
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/// @brief binary greatest common divisor
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/// @author http://en.wikipedia.org/wiki/Binary_GCD_algorithm
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/// note: T must be an unsigned type
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////////////////////////////////////////////////////////////////////////////////
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template <typename T>
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static T binaryGcd(T u, T v) {
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if (u == 0) {
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return v;
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}
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if (v == 0) {
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return u;
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}
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int shift;
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for (shift = 0; ((u | v) & 1) == 0; ++shift) {
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u >>= 1;
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v >>= 1;
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}
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while ((u & 1) == 0) {
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u >>= 1;
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}
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do {
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while ((v & 1) == 0) {
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v >>= 1;
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}
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if (u > v) {
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std::swap(v, u);
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}
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v = v - u;
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} while (v != 0);
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return u << shift;
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}
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} // namespace basics
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} // namespace arangodb
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#endif
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