1593354388
Replaced VelocityTracker with a faster and more accurate native implementation. This avoids the duplicate maintenance overhead of having two implementations. The new algorithm requires that the sample duration be at least 10ms in order to contribute to the velocity calculation. This ensures that the velocity is not severely overestimated when samples arrive in bursts. The new algorithm computes the exponentially weighted moving average using weights based on the relative duration of successive sample periods. The new algorithm is also more careful about how it handles individual pointers going down or up and their effects on the collected movement traces. The intent is to preserve the last known velocity of pointers as they go up while also ensuring that other motion samples do not count twice in that case. Bug: 4086785 Change-Id: I2632321232c64d6b8faacdb929e33f60e64dcdd3
81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef UTILS_BITSET_H
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#define UTILS_BITSET_H
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#include <stdint.h>
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/*
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* Contains some bit manipulation helpers.
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*/
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namespace android {
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// A simple set of 32 bits that can be individually marked or cleared.
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struct BitSet32 {
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uint32_t value;
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inline BitSet32() : value(0) { }
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explicit inline BitSet32(uint32_t value) : value(value) { }
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// Gets the value associated with a particular bit index.
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static inline uint32_t valueForBit(uint32_t n) { return 0x80000000 >> n; }
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// Clears the bit set.
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inline void clear() { value = 0; }
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// Returns the number of marked bits in the set.
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inline uint32_t count() const { return __builtin_popcount(value); }
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// Returns true if the bit set does not contain any marked bits.
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inline bool isEmpty() const { return ! value; }
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// Returns true if the specified bit is marked.
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inline bool hasBit(uint32_t n) const { return value & valueForBit(n); }
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// Marks the specified bit.
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inline void markBit(uint32_t n) { value |= valueForBit(n); }
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// Clears the specified bit.
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inline void clearBit(uint32_t n) { value &= ~ valueForBit(n); }
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// Finds the first marked bit in the set.
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// Result is undefined if all bits are unmarked.
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inline uint32_t firstMarkedBit() const { return __builtin_clz(value); }
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// Finds the first unmarked bit in the set.
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// Result is undefined if all bits are marked.
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inline uint32_t firstUnmarkedBit() const { return __builtin_clz(~ value); }
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// Finds the last marked bit in the set.
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// Result is undefined if all bits are unmarked.
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inline uint32_t lastMarkedBit() const { return 31 - __builtin_ctz(value); }
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// Gets the index of the specified bit in the set, which is the number of
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// marked bits that appear before the specified bit.
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inline uint32_t getIndexOfBit(uint32_t n) const {
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return __builtin_popcount(value & ~(0xffffffffUL >> n));
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}
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inline bool operator== (const BitSet32& other) const { return value == other.value; }
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inline bool operator!= (const BitSet32& other) const { return value != other.value; }
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};
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} // namespace android
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#endif // UTILS_BITSET_H
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