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- // Copyright 2014 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef UI_EVENTS_GESTURE_DETECTION_BITSET_32_H_
- #define UI_EVENTS_GESTURE_DETECTION_BITSET_32_H_
- #include <stdint.h>
- #include "base/check_op.h"
- namespace ui {
- // Port of BitSet32 from Android
- // * platform/system/core/include/utils/BitSet.h
- // * Change-Id: 02c9460a0a05f27e0501f9e64cdf24091e7d3579
- // * Please update the Change-Id as upstream Android changes are pulled.
- struct BitSet32 {
- uint32_t value;
- inline BitSet32() : value(0) {}
- explicit inline BitSet32(uint32_t value) : value(value) {}
- // Gets the value associated with a particular bit index.
- static inline uint32_t value_for_bit(uint32_t n) {
- DCHECK_LE(n, 31U);
- return 0x80000000 >> n;
- }
- // Clears the bit set.
- inline void clear() { value = 0; }
- // Returns the number of marked bits in the set.
- inline uint32_t count() const { return popcnt(value); }
- // Returns true if the bit set does not contain any marked bits.
- inline bool is_empty() const { return !value; }
- // Returns true if the bit set does not contain any unmarked bits.
- inline bool is_full() const { return value == 0xffffffff; }
- // Returns true if the specified bit is marked.
- inline bool has_bit(uint32_t n) const {
- return (value & value_for_bit(n)) != 0;
- }
- // Marks the specified bit.
- inline void mark_bit(uint32_t n) { value |= value_for_bit(n); }
- // Clears the specified bit.
- inline void clear_bit(uint32_t n) { value &= ~value_for_bit(n); }
- // Finds the first marked bit in the set.
- // Result is undefined if all bits are unmarked.
- inline uint32_t first_marked_bit() const { return clz(value); }
- // Finds the first unmarked bit in the set.
- // Result is undefined if all bits are marked.
- inline uint32_t first_unmarked_bit() const { return clz(~value); }
- // Finds the last marked bit in the set.
- // Result is undefined if all bits are unmarked.
- inline uint32_t last_marked_bit() const { return 31 - ctz(value); }
- // Finds the first marked bit in the set and clears it. Returns the bit
- // index.
- // Result is undefined if all bits are unmarked.
- inline uint32_t clear_first_marked_bit() {
- uint32_t n = first_marked_bit();
- clear_bit(n);
- return n;
- }
- // Finds the first unmarked bit in the set and marks it. Returns the bit
- // index.
- // Result is undefined if all bits are marked.
- inline uint32_t mark_first_unmarked_bit() {
- uint32_t n = first_unmarked_bit();
- mark_bit(n);
- return n;
- }
- // Finds the last marked bit in the set and clears it. Returns the bit index.
- // Result is undefined if all bits are unmarked.
- inline uint32_t clear_last_marked_bit() {
- uint32_t n = last_marked_bit();
- clear_bit(n);
- return n;
- }
- // Gets the index of the specified bit in the set, which is the number of
- // marked bits that appear before the specified bit.
- inline uint32_t get_index_of_bit(uint32_t n) const {
- DCHECK_LE(n, 31U);
- return popcnt(value & ~(0xffffffffUL >> n));
- }
- inline bool operator==(const BitSet32& other) const {
- return value == other.value;
- }
- inline bool operator!=(const BitSet32& other) const {
- return value != other.value;
- }
- inline BitSet32 operator&(const BitSet32& other) const {
- return BitSet32(value & other.value);
- }
- inline BitSet32& operator&=(const BitSet32& other) {
- value &= other.value;
- return *this;
- }
- inline BitSet32 operator|(const BitSet32& other) const {
- return BitSet32(value | other.value);
- }
- inline BitSet32& operator|=(const BitSet32& other) {
- value |= other.value;
- return *this;
- }
- private:
- #if defined(COMPILER_GCC) || defined(__clang__)
- static inline uint32_t popcnt(uint32_t v) { return __builtin_popcountl(v); }
- // We use these helpers as the signature of __builtin_c{l,t}z has
- // "unsigned int" for the input, which is only guaranteed to be 16b, not 32.
- // The compiler should optimize this away.
- static inline uint32_t clz(uint32_t v) {
- if (sizeof(unsigned int) == sizeof(uint32_t)) {
- return __builtin_clz(v);
- } else {
- return __builtin_clzl(v);
- }
- }
- static inline uint32_t ctz(uint32_t v) {
- if (sizeof(unsigned int) == sizeof(uint32_t)) {
- return __builtin_ctz(v);
- } else {
- return __builtin_ctzl(v);
- }
- }
- #else
- // http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
- static inline uint32_t popcnt(uint32_t v) {
- v = v - ((v >> 1) & 0x55555555);
- v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
- return (((v + (v >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
- }
- // TODO(jdduke): Use intrinsics (BitScan{Forward,Reverse}) with MSVC.
- static inline uint32_t clz(uint32_t v) {
- v |= (v >> 1);
- v |= (v >> 2);
- v |= (v >> 4);
- v |= (v >> 8);
- v |= (v >> 16);
- return 32 - popcnt(v);
- }
- static inline uint32_t ctz(uint32_t v) {
- return popcnt((v & static_cast<uint32_t>(-static_cast<int>(v))) - 1);
- }
- #endif
- };
- } // namespace ui
- #endif // UI_EVENTS_GESTURE_DETECTION_BITSET_32_H_
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