c34026b101
note: done using ```sh git grep -l "2010-2024 Google" | xargs sed -i 's/2010-2024 Google/2010-2025 Google/' ```
53 lines
1.3 KiB
C++
53 lines
1.3 KiB
C++
// Copyright 2010-2025 Google LLC
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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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#include "ortools/util/cached_log.h"
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#include "ortools/base/logging.h"
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namespace operations_research {
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CachedLog::CachedLog() {}
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CachedLog::~CachedLog() {}
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namespace {
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double FastLog2(int64_t input) {
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#if defined(_MSC_VER) || defined(__ANDROID__)
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return log(static_cast<double>(input)) / log(2.0L);
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#else
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return log2(input);
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#endif
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}
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} // namespace
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void CachedLog::Init(int size) {
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CHECK(cache_.empty());
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CHECK_GT(size, 0);
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cache_.resize(size, 0.0);
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for (int i = 0; i < size; ++i) {
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cache_[i] = FastLog2(i + 1);
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}
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}
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double CachedLog::Log2(int64_t input) const {
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CHECK_GE(input, 1);
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if (input <= cache_.size()) {
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return cache_[input - 1];
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} else {
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return FastLog2(input);
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}
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}
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} // namespace operations_research
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