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/*
* Copyright 2019 The libgav1 Authors
*
* 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 LIBGAV1_SRC_UTILS_BIT_MASK_SET_H_
#define LIBGAV1_SRC_UTILS_BIT_MASK_SET_H_
#include <cstdint>
namespace libgav1 {
// This class is used to check if a given value is equal to one of the several
// predetermined values using a bit mask instead of a chain of comparisons and
// ||s. This usually results in fewer instructions.
//
// Usage:
// constexpr BitMaskSet set(value1, value2);
// set.Contains(value1) => returns true.
// set.Contains(value3) => returns false.
class BitMaskSet {
public:
explicit constexpr BitMaskSet(uint32_t mask) : mask_(mask) {}
constexpr BitMaskSet(int v1, int v2) : mask_((1U << v1) | (1U << v2)) {}
constexpr BitMaskSet(int v1, int v2, int v3)
: mask_((1U << v1) | (1U << v2) | (1U << v3)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4, int v5)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4) | (1U << v5)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4, int v5, int v6)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4) | (1U << v5) |
(1U << v6)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4, int v5, int v6, int v7)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4) | (1U << v5) |
(1U << v6) | (1U << v7)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4, int v5, int v6, int v7,
int v8, int v9)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4) | (1U << v5) |
(1U << v6) | (1U << v7) | (1U << v8) | (1U << v9)) {}
constexpr BitMaskSet(int v1, int v2, int v3, int v4, int v5, int v6, int v7,
int v8, int v9, int v10)
: mask_((1U << v1) | (1U << v2) | (1U << v3) | (1U << v4) | (1U << v5) |
(1U << v6) | (1U << v7) | (1U << v8) | (1U << v9) | (1U << v10)) {
}
constexpr bool Contains(uint8_t value) const {
return MaskContainsValue(mask_, value);
}
static constexpr bool MaskContainsValue(uint32_t mask, uint8_t value) {
return ((mask >> value) & 1) != 0;
}
private:
const uint32_t mask_;
};
} // namespace libgav1
#endif // LIBGAV1_SRC_UTILS_BIT_MASK_SET_H_
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