| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkBitSet_DEFINED |
| #define SkBitSet_DEFINED |
| |
| #include "include/private/base/SkTemplates.h" |
| #include "include/private/base/SkMalloc.h" |
| #include "src/base/SkMathPriv.h" |
| |
| #include <climits> |
| #include <cstring> |
| #include <limits> |
| #include <memory> |
| #include <optional> |
| |
| class SkBitSet { |
| public: |
| explicit SkBitSet(size_t size) |
| : fSize(size) |
| // May http://wg21.link/p0593 be accepted. |
| , fChunks((Chunk*)sk_calloc_throw(NumChunksFor(fSize) * sizeof(Chunk))) |
| {} |
| |
| SkBitSet(const SkBitSet&) = delete; |
| SkBitSet& operator=(const SkBitSet&) = delete; |
| SkBitSet(SkBitSet&& that) { *this = std::move(that); } |
| SkBitSet& operator=(SkBitSet&& that) { |
| if (this != &that) { |
| this->fSize = that.fSize; |
| this->fChunks = std::move(that.fChunks); |
| that.fSize = 0; |
| } |
| return *this; |
| } |
| ~SkBitSet() = default; |
| |
| /** Set the value of the index-th bit to true. */ |
| void set(size_t index) { |
| SkASSERT(index < fSize); |
| *this->chunkFor(index) |= ChunkMaskFor(index); |
| } |
| |
| /** Sets every bit in the bitset to true. */ |
| void set() { |
| Chunk* chunks = fChunks.get(); |
| const size_t numChunks = NumChunksFor(fSize); |
| std::memset(chunks, 0xFF, sizeof(Chunk) * numChunks); |
| } |
| |
| /** Set the value of the index-th bit to false. */ |
| void reset(size_t index) { |
| SkASSERT(index < fSize); |
| *this->chunkFor(index) &= ~ChunkMaskFor(index); |
| } |
| |
| /** Sets every bit in the bitset to false. */ |
| void reset() { |
| Chunk* chunks = fChunks.get(); |
| const size_t numChunks = NumChunksFor(fSize); |
| std::memset(chunks, 0, sizeof(Chunk) * numChunks); |
| } |
| |
| bool test(size_t index) const { |
| SkASSERT(index < fSize); |
| return SkToBool(*this->chunkFor(index) & ChunkMaskFor(index)); |
| } |
| |
| size_t size() const { |
| return fSize; |
| } |
| |
| // Calls f(size_t index) for each set index. |
| template<typename FN> |
| void forEachSetIndex(FN f) const { |
| const Chunk* chunks = fChunks.get(); |
| const size_t numChunks = NumChunksFor(fSize); |
| for (size_t i = 0; i < numChunks; ++i) { |
| if (Chunk chunk = chunks[i]) { // There are set bits |
| const size_t index = i * kChunkBits; |
| for (size_t j = 0; j < kChunkBits; ++j) { |
| if (0x1 & (chunk >> j)) { |
| f(index + j); |
| } |
| } |
| } |
| } |
| } |
| |
| using OptionalIndex = std::optional<size_t>; |
| |
| // If any bits are set, returns the index of the first. |
| OptionalIndex findFirst() { |
| const Chunk* chunks = fChunks.get(); |
| const size_t numChunks = NumChunksFor(fSize); |
| for (size_t i = 0; i < numChunks; ++i) { |
| if (Chunk chunk = chunks[i]) { // There are set bits |
| static_assert(kChunkBits <= std::numeric_limits<uint32_t>::digits, "SkCTZ"); |
| const size_t bitIndex = i * kChunkBits + SkCTZ(chunk); |
| return OptionalIndex(bitIndex); |
| } |
| } |
| return OptionalIndex(); |
| } |
| |
| // If any bits are not set, returns the index of the first. |
| OptionalIndex findFirstUnset() { |
| const Chunk* chunks = fChunks.get(); |
| const size_t numChunks = NumChunksFor(fSize); |
| for (size_t i = 0; i < numChunks; ++i) { |
| if (Chunk chunk = ~chunks[i]) { // if there are unset bits ... |
| static_assert(kChunkBits <= std::numeric_limits<uint32_t>::digits, "SkCTZ"); |
| const size_t bitIndex = i * kChunkBits + SkCTZ(chunk); |
| if (bitIndex >= fSize) { |
| break; |
| } |
| return OptionalIndex(bitIndex); |
| } |
| } |
| return OptionalIndex(); |
| } |
| |
| private: |
| size_t fSize; |
| |
| using Chunk = uint32_t; |
| static_assert(std::numeric_limits<Chunk>::radix == 2); |
| inline static constexpr size_t kChunkBits = std::numeric_limits<Chunk>::digits; |
| static_assert(kChunkBits == sizeof(Chunk)*CHAR_BIT, "SkBitSet must use every bit in a Chunk"); |
| std::unique_ptr<Chunk, SkOverloadedFunctionObject<void(void*), sk_free>> fChunks; |
| |
| Chunk* chunkFor(size_t index) const { |
| return fChunks.get() + (index / kChunkBits); |
| } |
| |
| static constexpr Chunk ChunkMaskFor(size_t index) { |
| return (Chunk)1 << (index & (kChunkBits-1)); |
| } |
| |
| static constexpr size_t NumChunksFor(size_t size) { |
| return (size + (kChunkBits-1)) / kChunkBits; |
| } |
| }; |
| |
| #endif |