mirror of
https://github.com/aykhans/AzSuicideDataVisualization.git
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112 lines
3.5 KiB
C++
112 lines
3.5 KiB
C++
// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. 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,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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#pragma once
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#include <cstdint>
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#include <memory>
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#include "arrow/buffer.h"
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#include "arrow/memory_pool.h"
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#include "arrow/result.h"
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#include "arrow/util/bit_util.h"
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#include "arrow/util/visibility.h"
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namespace arrow {
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namespace internal {
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// A std::generate() like function to write sequential bits into a bitmap area.
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// Bits preceding the bitmap area are preserved, bits following the bitmap
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// area may be clobbered.
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template <class Generator>
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void GenerateBits(uint8_t* bitmap, int64_t start_offset, int64_t length, Generator&& g) {
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if (length == 0) {
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return;
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}
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uint8_t* cur = bitmap + start_offset / 8;
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uint8_t bit_mask = bit_util::kBitmask[start_offset % 8];
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uint8_t current_byte = *cur & bit_util::kPrecedingBitmask[start_offset % 8];
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for (int64_t index = 0; index < length; ++index) {
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const bool bit = g();
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current_byte = bit ? (current_byte | bit_mask) : current_byte;
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bit_mask = static_cast<uint8_t>(bit_mask << 1);
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if (bit_mask == 0) {
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bit_mask = 1;
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*cur++ = current_byte;
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current_byte = 0;
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}
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}
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if (bit_mask != 1) {
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*cur++ = current_byte;
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}
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}
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// Like GenerateBits(), but unrolls its main loop for higher performance.
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template <class Generator>
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void GenerateBitsUnrolled(uint8_t* bitmap, int64_t start_offset, int64_t length,
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Generator&& g) {
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static_assert(std::is_same<decltype(std::declval<Generator>()()), bool>::value,
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"Functor passed to GenerateBitsUnrolled must return bool");
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if (length == 0) {
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return;
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}
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uint8_t current_byte;
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uint8_t* cur = bitmap + start_offset / 8;
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const uint64_t start_bit_offset = start_offset % 8;
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uint8_t bit_mask = bit_util::kBitmask[start_bit_offset];
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int64_t remaining = length;
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if (bit_mask != 0x01) {
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current_byte = *cur & bit_util::kPrecedingBitmask[start_bit_offset];
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while (bit_mask != 0 && remaining > 0) {
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current_byte |= g() * bit_mask;
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bit_mask = static_cast<uint8_t>(bit_mask << 1);
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--remaining;
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}
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*cur++ = current_byte;
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}
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int64_t remaining_bytes = remaining / 8;
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uint8_t out_results[8];
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while (remaining_bytes-- > 0) {
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for (int i = 0; i < 8; ++i) {
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out_results[i] = g();
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}
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*cur++ = (out_results[0] | out_results[1] << 1 | out_results[2] << 2 |
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out_results[3] << 3 | out_results[4] << 4 | out_results[5] << 5 |
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out_results[6] << 6 | out_results[7] << 7);
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}
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int64_t remaining_bits = remaining % 8;
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if (remaining_bits) {
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current_byte = 0;
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bit_mask = 0x01;
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while (remaining_bits-- > 0) {
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current_byte |= g() * bit_mask;
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bit_mask = static_cast<uint8_t>(bit_mask << 1);
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}
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*cur++ = current_byte;
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}
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}
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} // namespace internal
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} // namespace arrow
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