| // 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. |
| |
| #include "arrow/util/bit_run_reader.h" |
| |
| #include <cstdint> |
| |
| #include "arrow/util/bit_util.h" |
| |
| namespace arrow { |
| namespace internal { |
| |
| #if ARROW_LITTLE_ENDIAN |
| |
| BitRunReader::BitRunReader(const uint8_t* bitmap, int64_t start_offset, int64_t length) |
| : bitmap_(bitmap + (start_offset / 8)), |
| position_(start_offset % 8), |
| length_(position_ + length) { |
| if (ARROW_PREDICT_FALSE(length == 0)) { |
| word_ = 0; |
| return; |
| } |
| |
| // On the initial load if there is an offset we need to account for this when |
| // loading bytes. Every other call to LoadWord() should only occur when |
| // position_ is a multiple of 64. |
| current_run_bit_set_ = !BitUtil::GetBit(bitmap, start_offset); |
| int64_t bits_remaining = length + position_; |
| |
| LoadWord(bits_remaining); |
| |
| // Prepare for inversion in NextRun. |
| // Clear out any preceding bits. |
| word_ = word_ & ~BitUtil::LeastSignificantBitMask(position_); |
| } |
| |
| #endif |
| |
| } // namespace internal |
| } // namespace arrow |