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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef UTILS_BITSET_H
#define UTILS_BITSET_H
#include <stdint.h>
/*
* Contains some bit manipulation helpers.
*/
namespace android {
// A simple set of 32 bits that can be individually marked or cleared.
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 valueForBit(uint32_t n) { 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 __builtin_popcount(value); }
// Returns true if the bit set does not contain any marked bits.
inline bool isEmpty() const { return ! value; }
// Returns true if the bit set does not contain any unmarked bits.
inline bool isFull() const { return value == 0xffffffff; }
// Returns true if the specified bit is marked.
inline bool hasBit(uint32_t n) const { return value & valueForBit(n); }
// Marks the specified bit.
inline void markBit(uint32_t n) { value |= valueForBit(n); }
// Clears the specified bit.
inline void clearBit(uint32_t n) { value &= ~ valueForBit(n); }
// Finds the first marked bit in the set.
// Result is undefined if all bits are unmarked.
inline uint32_t firstMarkedBit() const { return __builtin_clz(value); }
// Finds the first unmarked bit in the set.
// Result is undefined if all bits are marked.
inline uint32_t firstUnmarkedBit() const { return __builtin_clz(~ value); }
// Finds the last marked bit in the set.
// Result is undefined if all bits are unmarked.
inline uint32_t lastMarkedBit() const { return 31 - __builtin_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 clearFirstMarkedBit() {
uint32_t n = firstMarkedBit();
clearBit(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 markFirstUnmarkedBit() {
uint32_t n = firstUnmarkedBit();
markBit(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 clearLastMarkedBit() {
uint32_t n = lastMarkedBit();
clearBit(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 getIndexOfBit(uint32_t n) const {
return __builtin_popcount(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; }
};
} // namespace android
#endif // UTILS_BITSET_H
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