/* Copyright 2021 The TensorFlow 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.
==============================================================================*/

#ifndef TENSORFLOW_LITE_DELEGATES_GPU_COMMON_TASKS_DEPTHWISE_CONV_3X3_STRIDE_H2_H_
#define TENSORFLOW_LITE_DELEGATES_GPU_COMMON_TASKS_DEPTHWISE_CONV_3X3_STRIDE_H2_H_

#include <vector>

#include "tensorflow/lite/delegates/gpu/common/operations.h"
#include "tensorflow/lite/delegates/gpu/common/task/buffer_desc.h"
#include "tensorflow/lite/delegates/gpu/common/task/gpu_operation.h"
#include "tensorflow/lite/delegates/gpu/common/task/texture2d_desc.h"

namespace tflite {
namespace gpu {

// Depth Wise Convolution for kernel 3x3
// require:
//   channels_multiplier = 1;
//   kernel_size = 3x3;
//   dilation.y = 1;
//   stride.y = 2;
class DepthWiseConv3x3StrideH2 : public GPUOperation {
 public:
  DepthWiseConv3x3StrideH2() = default;
  void GetPossibleKernelWorkGroups(
      TuningType tuning_type, const GpuInfo& gpu_info,
      const KernelInfo& kernel_info,
      std::vector<int3>* work_groups) const override;
  int3 GetGridSize() const override;

  // Move only
  DepthWiseConv3x3StrideH2(DepthWiseConv3x3StrideH2&& kernel) = default;
  DepthWiseConv3x3StrideH2& operator=(DepthWiseConv3x3StrideH2&& kernel) =
      default;
  DepthWiseConv3x3StrideH2(const DepthWiseConv3x3StrideH2&) = delete;
  DepthWiseConv3x3StrideH2& operator=(const DepthWiseConv3x3StrideH2&) = delete;

 private:
  explicit DepthWiseConv3x3StrideH2(const OperationDef& definition)
      : GPUOperation(definition) {}
  friend DepthWiseConv3x3StrideH2 CreateDepthWiseConv3x3StrideH2(
      const OperationDef& definition,
      const DepthwiseConvolution2DAttributes& attr, const GpuInfo& gpu_info);

  template <DataType T>
  void UploadWeightsAndBiases(const tflite::gpu::Tensor<OHWI, T>& weights,
                              const tflite::gpu::Tensor<Linear, T>& biases,
                              bool weights_are_buffer);
  template <DataType S, typename T>
  void RearrangeWeightsAndBiasesData(
      const tflite::gpu::Tensor<OHWI, S>& weights,
      const tflite::gpu::Tensor<Linear, S>& biases, absl::Span<T> dst);

  bool local_mem_uploads_;
};

template <DataType T>
void DepthWiseConv3x3StrideH2::UploadWeightsAndBiases(
    const tflite::gpu::Tensor<OHWI, T>& weights,
    const tflite::gpu::Tensor<Linear, T>& biases, bool weights_are_buffer) {
  const int src_depth = DivideRoundUp(weights.shape.i, 4);
  int texture_width = 10;  // 3x3 kernel + 1 bias
  int texture_height = src_depth;
  const int elements_count = texture_width * texture_height;
  const bool fp32_weights = definition_.precision == CalculationsPrecision::F32;
  const int float4_size = fp32_weights ? 16 : 8;

  std::vector<uint8_t> data(float4_size * elements_count);
  if (fp32_weights) {
    float4* ptr = reinterpret_cast<float4*>(data.data());
    RearrangeWeightsAndBiasesData(weights, biases,
                                  absl::MakeSpan(ptr, elements_count));
  } else {
    half4* ptr = reinterpret_cast<half4*>(data.data());
    RearrangeWeightsAndBiasesData(weights, biases,
                                  absl::MakeSpan(ptr, elements_count));
  }

  if (weights_are_buffer) {
    BufferDescriptor desc;
    desc.element_type = fp32_weights ? DataType::FLOAT32 : DataType::FLOAT16;
    desc.element_size = 4;
    desc.size = float4_size * elements_count;
    desc.data = std::move(data);
    args_.AddObject("weights",
                    absl::make_unique<BufferDescriptor>(std::move(desc)));
  } else {
    Texture2DDescriptor desc;
    desc.element_type = fp32_weights ? DataType::FLOAT32 : DataType::FLOAT16;
    desc.size = int2(texture_width, texture_height);
    desc.data = std::move(data);
    args_.AddObject("weights",
                    absl::make_unique<Texture2DDescriptor>(std::move(desc)));
  }
}

template <DataType S, typename T>
void DepthWiseConv3x3StrideH2::RearrangeWeightsAndBiasesData(
    const tflite::gpu::Tensor<OHWI, S>& weights,
    const tflite::gpu::Tensor<Linear, S>& biases, absl::Span<T> dst) {
  const int src_depth = DivideRoundUp(weights.shape.i, 4);

  int counter = 0;
  for (int s = 0; s < src_depth; ++s) {
    for (int y = 0; y < 3; ++y) {
      for (int x = 0; x < 3; ++x) {
        T filter_val;
        for (int i = 0; i < 4; ++i) {
          const int s_ch = s * 4 + i;
          if (s_ch < weights.shape.i) {
            const int f_index = weights.shape.LinearIndex({0, y, x, s_ch});
            filter_val[i] = weights.data[f_index];
          } else {
            filter_val[i] = 0.0f;
          }
        }
        dst[counter++] = filter_val;
      }
    }

    T bias_val;
    for (int i = 0; i < 4; ++i) {
      const int dst_ch = s * 4 + i;
      bias_val[i] = dst_ch >= biases.shape.v ? 0.0f : biases.data[dst_ch];
    }
    dst[counter++] = bias_val;
  }
}

DepthWiseConv3x3StrideH2 CreateDepthWiseConv3x3StrideH2(
    const OperationDef& definition,
    const DepthwiseConvolution2DAttributes& attr, const GpuInfo& gpu_info);

bool IsDepthWiseConv3x3StrideH2Supported(
    const DepthwiseConvolution2DAttributes& attr);

}  // namespace gpu
}  // namespace tflite

#endif  // TENSORFLOW_LITE_DELEGATES_GPU_COMMON_TASKS_DEPTHWISE_CONV_3X3_STRIDE_H2_H_
