mirror of
https://github.com/facebookresearch/faiss.git
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45 lines
1.1 KiB
C++
45 lines
1.1 KiB
C++
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD+Patents license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "RemapIndices.h"
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#include "../../FaissAssert.h"
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namespace faiss { namespace gpu {
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// Utility function to translate (list id, offset) to a user index on
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// the CPU. In a cpp in order to use OpenMP
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void ivfOffsetToUserIndex(
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long* indices,
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int numLists,
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int queries,
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int k,
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const std::vector<std::vector<long>>& listOffsetToUserIndex) {
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FAISS_ASSERT(numLists == listOffsetToUserIndex.size());
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#pragma omp parallel for
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for (int q = 0; q < queries; ++q) {
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for (int r = 0; r < k; ++r) {
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long offsetIndex = indices[q * k + r];
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if (offsetIndex < 0) continue;
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int listId = (int) (offsetIndex >> 32);
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int listOffset = (int) (offsetIndex & 0xffffffff);
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FAISS_ASSERT(listId < numLists);
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auto& listIndices = listOffsetToUserIndex[listId];
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FAISS_ASSERT(listOffset < listIndices.size());
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indices[q * k + r] = listIndices[listOffset];
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}
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}
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}
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} } // namespace
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