mirror of https://gitee.com/bigwinds/arangodb
52 lines
1.7 KiB
C
52 lines
1.7 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 Max Neunhoeffer
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_BASICS_ASSOC_HELPERS_H
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#define ARANGODB_BASICS_ASSOC_HELPERS_H 1
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#include "Basics/Common.h"
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/// @brief incrementing a uint64_t modulo a number with wraparound
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static inline uint64_t TRI_IncModU64(uint64_t i, uint64_t len) {
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// Note that the dummy variable gives the compiler a (good) chance to
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// use a conditional move instruction instead of a branch. This actually
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// works on modern gcc.
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uint64_t dummy;
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dummy = (++i) - len;
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return i < len ? i : dummy;
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}
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static inline uint64_t TRI_DecModU64(uint64_t i, uint64_t len) {
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if ((i--) != 0) {
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return i;
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}
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return len - 1;
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}
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/// @brief a trivial hash function for uint64_t to uint32_t
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static inline uint32_t TRI_64To32(uint64_t x) {
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return static_cast<uint32_t>(x >> 32) ^ static_cast<uint32_t>(x);
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}
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#endif
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