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/// @example sum.cpp
/// > Annotated version: @ref sum_example_cpp

/// @page sum_example_cpp_brief
/// @brief This C++ API example demonstrates how to create and execute a
/// [Sum](@ref dev_guide_sum) primitive.

/// @page sum_example_cpp Sum Primitive Example
/// \copybrief sum_example_cpp_brief
///
/// Key optimizations included in this example:
/// - Identical memory formats for source (src) and destination (dst) tensors.
///
/// @include sum.cpp

#include <algorithm>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>

#include "example_utils.hpp"
#include "oneapi/dnnl/dnnl.hpp"

using namespace dnnl;

void sum_example(dnnl::engine::kind engine_kind) {

    // Create execution dnnl::engine.
    dnnl::engine engine(engine_kind, 0);

    // Create dnnl::stream.
    dnnl::stream engine_stream(engine);

    // Tensor dimensions.
    const memory::dim N = 3, // batch size
            IC = 3, // channels
            IH = 227, // tensor height
            IW = 227; // tensor width

    // Source (src) and destination (dst) tensors dimensions.
    memory::dims src_dims = {N, IC, IH, IW};

    // Allocate buffers.
    std::vector<float> src_data(product(src_dims));
    std::vector<float> dst_data(product(src_dims));

    // Initialize src.
    std::generate(src_data.begin(), src_data.end(), []() {
        static int i = 0;
        return std::cos(i++ / 10.f);
    });

    // Number of src tensors.
    const int num_src = 10;

    // Scaling factors.
    std::vector<float> scales(num_src);
    std::generate(scales.begin(), scales.end(),
            [](int n = 0) { return sin(float(n)); });

    // Create an array of memory descriptors and memory objects for src tensors.
    std::vector<memory::desc> src_md;
    std::vector<memory> src_mem;

    for (int n = 0; n < num_src; ++n) {
        src_md.emplace_back(
                src_dims, memory::data_type::f32, memory::format_tag::nchw);
        src_mem.emplace_back(src_md.back(), engine);

        // Write data to memory object's handle.
        write_to_dnnl_memory(src_data.data(), src_mem.back());
    }

    // Create primitive descriptor.
    auto sum_pd = sum::primitive_desc(engine, scales, src_md);

    // Create the primitive.
    auto sum_prim = sum(sum_pd);

    // Create memory object for dst.
    auto dst_mem = memory(sum_pd.dst_desc(), engine);

    // Primitive arguments.
    std::unordered_map<int, memory> sum_args;
    sum_args.insert({DNNL_ARG_DST, dst_mem});
    for (int n = 0; n < num_src; ++n) {
        sum_args.insert({DNNL_ARG_MULTIPLE_SRC + n, src_mem[n]});
    }

    // Primitive execution: sum.
    sum_prim.execute(engine_stream, sum_args);

    // Wait for the computation to finalize.
    engine_stream.wait();

    // Read data from memory object's handle.
    read_from_dnnl_memory(dst_data.data(), dst_mem);
}

int main(int argc, char **argv) {
    return handle_example_errors(sum_example, parse_engine_kind(argc, argv));
}
