text: // Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
  //
  // 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.
  
  #pragma once
  
  #include <algorithm>
  #include <string>
  #include <vector>
  #include "lite/operators/op_params.h"
  #include "lite/utils/cp_logging.h"
  
  namespace paddle {
  namespace lite {
  namespace arm {
  namespace math {
  
  template <typename T>
  void concat_func(const std::vector<lite::Tensor*>& input,
                   const int axis,
                   lite::Tensor* output) {
    size_t num = input.size();
    auto dim_0 = input[0]->dims();
    int64_t concat_input_size = 1;
    int64_t num_cancats = 1;
    for (int i = axis + 1; i < dim_0.size(); i++) {
      concat_input_size *= dim_0[i];
    }
    for (int i = 0; i < axis; i++) {
      num_cancats *= dim_0[i];
    }
  
    auto* dst_ptr = output->mutable_data<T>();
    const int out_concat_axis = output->dims()[axis];
    int64_t offset_concat_axis = 0;
    int64_t out_sum = out_concat_axis * concat_input_size;
    for (int n = 0; n < num; n++) {
      auto dims = input[n]->dims();
      auto* src_ptr = input[n]->data<T>();
      int64_t in_concat_axis = dims[axis];
      auto* dout_ptr = dst_ptr + offset_concat_axis * concat_input_size;
      int64_t in_sum = in_concat_axis * concat_input_size;
      for (int i = 0; i < num_cancats; i++) {
        std::memcpy(dout_ptr, src_ptr, sizeof(T) * in_sum);
        dout_ptr += out_sum;
        src_ptr += in_sum;
      }
      offset_concat_axis += in_concat_axis;
    }
  }
  
  }  // namespace math
  }  // namespace arm
  }  // namespace lite
  }  // namespace paddle
  