| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| #ifndef IMPALA_BIT_UTIL_H |
| #define IMPALA_BIT_UTIL_H |
| |
| #include <cstdint> |
| |
| #include "kudu/gutil/port.h" |
| |
| namespace kudu { |
| |
| // Utility class to do standard bit tricks |
| // TODO: is this in boost or something else like that? |
| class BitUtil { |
| public: |
| // Returns the ceil of value/divisor |
| static inline int Ceil(int value, int divisor) { |
| return value / divisor + (value % divisor != 0); |
| } |
| |
| // Similar to the above, but a bit optimized for the case when the divisor |
| // is a power of two: LOG2_DIV is log2(divisor), e.g. 3 for the divisor of 8. |
| template <int LOG2_DIV> |
| static inline int Ceil(int value) { |
| constexpr int kDivisor = 1 << LOG2_DIV; |
| constexpr int kComplement = kDivisor - 1; |
| constexpr int kComplementMask = -kDivisor; |
| return ((value + kComplement) & kComplementMask) >> LOG2_DIV; |
| } |
| |
| // Returns the 'num_bits' least-significant bits of 'v'. |
| static inline uint64_t TrailingBits(uint64_t v, int num_bits) { |
| if (PREDICT_FALSE(num_bits == 0)) return 0; |
| if (PREDICT_FALSE(num_bits >= 64)) return v; |
| int n = 64 - num_bits; |
| return (v << n) >> n; |
| } |
| |
| static inline uint64_t ShiftLeftZeroOnOverflow(uint64_t v, int num_bits) { |
| if (PREDICT_FALSE(num_bits >= 64)) return 0; |
| return v << num_bits; |
| } |
| |
| static inline uint64_t ShiftRightZeroOnOverflow(uint64_t v, int num_bits) { |
| if (PREDICT_FALSE(num_bits >= 64)) return 0; |
| return v >> num_bits; |
| } |
| }; |
| |
| } // namespace kudu |
| |
| #endif |