/*

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 */

#pragma once

#include <cstddef>

#include <cstdint>

namespace faiss {

/// Returns the distance to a single code.

template <typename PQDecoderT>

inline float distance_single_code_generic(

        // number of subquantizers

        const size_t M,

        // number of bits per quantization index

        const size_t nbits,

        // precomputed distances, layout (M, ksub)

        const float* sim_table,

        // the code

        const uint8_t* code) {

    PQDecoderT decoder(code, nbits);

    const size_t ksub = 1 << nbits;

    const float* tab = sim_table;

    float result = 0;

    for (size_t m = 0; m < M; m++) {

        result += tab[decoder.decode()];

        tab += ksub;

    }

    return result;

}

Unexecuted instantiation: _ZN5faiss28distance_single_code_genericINS_11PQDecoder16EEEfmmPKfPKh

Unexecuted instantiation: _ZN5faiss28distance_single_code_genericINS_16PQDecoderGenericEEEfmmPKfPKh

/// Combines 4 operations of distance_single_code()

/// General-purpose version.

template <typename PQDecoderT>

inline void distance_four_codes_generic(

        // number of subquantizers

        const size_t M,

        // number of bits per quantization index

        const size_t nbits,

        // precomputed distances, layout (M, ksub)

        const float* sim_table,

        // codes

        const uint8_t* __restrict code0,

        const uint8_t* __restrict code1,

        const uint8_t* __restrict code2,

        const uint8_t* __restrict code3,

        // computed distances

        float& result0,

        float& result1,

        float& result2,

        float& result3) {

    PQDecoderT decoder0(code0, nbits);

    PQDecoderT decoder1(code1, nbits);

    PQDecoderT decoder2(code2, nbits);

    PQDecoderT decoder3(code3, nbits);

    const size_t ksub = 1 << nbits;

    const float* tab = sim_table;

    result0 = 0;

    result1 = 0;

    result2 = 0;

    result3 = 0;

    for (size_t m = 0; m < M; m++) {

        result0 += tab[decoder0.decode()];

        result1 += tab[decoder1.decode()];

        result2 += tab[decoder2.decode()];

        result3 += tab[decoder3.decode()];

        tab += ksub;

    }

}

Unexecuted instantiation: _ZN5faiss27distance_four_codes_genericINS_11PQDecoder16EEEvmmPKfPKhS5_S5_S5_RfS6_S6_S6_

Unexecuted instantiation: _ZN5faiss27distance_four_codes_genericINS_16PQDecoderGenericEEEvmmPKfPKhS5_S5_S5_RfS6_S6_S6_

} // namespace faiss