c1bc70b711
A lot of files were missing copyright field in the header and
the Blender Foundation contributed to them in a sense of bug
fixing and general maintenance.
This change makes it explicit that those files are at least
partially copyrighted by the Blender Foundation.
Note that this does not make it so the Blender Foundation is
the only holder of the copyright in those files, and developers
who do not have a signed contract with the foundation still
hold the copyright as well.
Another aspect of this change is using SPDX format for the
header. We already used it for the license specification,
and now we state it for the copyright as well, following the
FAQ:
https://reuse.software/faq/
96 lines
2.7 KiB
C++
96 lines
2.7 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Foundation
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#pragma once
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#include "BLI_bit_vector.hh"
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namespace blender::bits {
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/**
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* A #BitGroupVector is a compact data structure that allows storing an arbitrary but fixed number
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* of bits per element. For example, it could be used to compactly store 5 bits per vertex in a
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* mesh. The data structure stores the bits in a way so that the #BitSpan for every element is
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* bounded according to #is_bounded_span. The makes sure that operations on entire groups can be
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* implemented efficiently. For example, one can easy `or` one group into another.
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*/
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template<int64_t InlineBufferCapacity = 64, typename Allocator = GuardedAllocator>
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class BitGroupVector {
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private:
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/**
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* Number of bits per group.
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*/
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int64_t group_size_ = 0;
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/**
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* Actually stored number of bits per group so that individual groups are bounded according to
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* #is_bounded_span.
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*/
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int64_t aligned_group_size_ = 0;
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BitVector<InlineBufferCapacity, Allocator> data_;
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static int64_t align_group_size(const int64_t group_size)
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{
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if (group_size < 64) {
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/* Align to next power of two so that a single group never spans across two ints. */
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return int64_t(power_of_2_max_u(uint32_t(group_size)));
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}
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/* Align to multiple of BitsPerInt. */
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return (group_size + BitsPerInt - 1) & ~(BitsPerInt - 1);
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}
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public:
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BitGroupVector() = default;
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BitGroupVector(const int64_t size_in_groups,
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const int64_t group_size,
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const bool value = false,
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Allocator allocator = {})
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: group_size_(group_size),
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aligned_group_size_(align_group_size(group_size)),
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data_(size_in_groups * aligned_group_size_, value, allocator)
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{
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BLI_assert(group_size >= 0);
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BLI_assert(size_in_groups >= 0);
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}
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/** Get all the bits at an index. */
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BoundedBitSpan operator[](const int64_t i) const
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{
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const int64_t offset = aligned_group_size_ * i;
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return {data_.data() + (offset >> BitToIntIndexShift),
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IndexRange(offset & BitIndexMask, group_size_)};
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}
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/** Get all the bits at an index. */
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MutableBoundedBitSpan operator[](const int64_t i)
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{
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const int64_t offset = aligned_group_size_ * i;
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return {data_.data() + (offset >> BitToIntIndexShift),
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IndexRange(offset & BitIndexMask, group_size_)};
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}
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/** Number of groups. */
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int64_t size() const
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{
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return aligned_group_size_ == 0 ? 0 : data_.size() / aligned_group_size_;
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}
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/** Number of bits per group. */
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int64_t group_size() const
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{
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return group_size_;
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}
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IndexRange index_range() const
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{
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return IndexRange{this->size()};
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}
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};
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} // namespace blender::bits
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namespace blender {
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using bits::BitGroupVector;
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}
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