TfLiteStatus Prepare(TfLiteContext* context, TfLiteNode* node) {
  auto* params =
      reinterpret_cast<TfLiteDepthwiseConvParams*>(node->builtin_data);
  OpData* data = reinterpret_cast<OpData*>(node->user_data);

  // TODO(ahentz): use could use GetOptionalInputTensor() here, but we need to
  // decide whether we are OK with optional tensors being completely absent, as
  // opposed to having -1 as their index.
  bool hasBias = NumInputs(node) == 3;

  TF_LITE_ENSURE(context, hasBias || NumInputs(node) == 2);
  const TfLiteTensor* input;
  TF_LITE_ENSURE_OK(context, GetInputSafe(context, node, kInputTensor, &input));
  const TfLiteTensor* filter;
  TF_LITE_ENSURE_OK(context,
                    GetInputSafe(context, node, kFilterTensor, &filter));
  const TfLiteTensor* bias = nullptr;

  TF_LITE_ENSURE_EQ(context, NumOutputs(node), 1);
  TfLiteTensor* output;
  TF_LITE_ENSURE_OK(context,
                    GetOutputSafe(context, node, kOutputTensor, &output));

  TF_LITE_ENSURE_EQ(context, NumDimensions(input), 4);
  TF_LITE_ENSURE_EQ(context, NumDimensions(filter), 4);

  const TfLiteType data_type = input->type;

  const TfLiteType filter_type = filter->type;
  const bool is_hybrid =
      data_type == kTfLiteFloat32 && filter_type == kTfLiteInt8;
  TF_LITE_ENSURE(context,
                 data_type == kTfLiteFloat32 || data_type == kTfLiteUInt8 ||
                     data_type == kTfLiteInt8 || data_type == kTfLiteInt16);
  TF_LITE_ENSURE_TYPES_EQ(context, output->type, data_type);
  if (!is_hybrid) {
    TF_LITE_ENSURE(context,
                   filter->type == data_type || data_type == kTfLiteInt16);
  }

  // Filter in DepthwiseConv is expected to be [1, H, W, O].
  TF_LITE_ENSURE_EQ(context, SizeOfDimension(filter, 0), 1);

  if (hasBias) {
    TF_LITE_ENSURE_OK(context, GetInputSafe(context, node, kBiasTensor, &bias));
    if (data_type == kTfLiteUInt8 || data_type == kTfLiteInt8) {
      TF_LITE_ENSURE_TYPES_EQ(context, bias->type, kTfLiteInt32);
      TF_LITE_ENSURE_EQ(context, bias->params.zero_point, 0);
    } else if (data_type == kTfLiteInt16) {
      TF_LITE_ENSURE_TYPES_EQ(context, bias->type, kTfLiteInt64);
      TF_LITE_ENSURE_EQ(context, bias->params.zero_point, 0);
      TF_LITE_ENSURE_EQ(context, input->params.zero_point, 0);
      TF_LITE_ENSURE_EQ(context, output->params.zero_point, 0);
    } else {
      TF_LITE_ENSURE_TYPES_EQ(context, bias->type, data_type);
    }
    TF_LITE_ENSURE_EQ(context, NumDimensions(bias), 1);
    TF_LITE_ENSURE_EQ(context, SizeOfDimension(filter, 3),
                      SizeOfDimension(bias, 0));
  }

  int channels_out = SizeOfDimension(filter, 3);
  int width = SizeOfDimension(input, 2);
  int height = SizeOfDimension(input, 1);
  int filter_width = SizeOfDimension(filter, 2);
  int filter_height = SizeOfDimension(filter, 1);
  int batches = SizeOfDimension(input, 0);

  // Matching GetWindowedOutputSize in TensorFlow.
  auto padding = params->padding;
  int out_width, out_height;

  data->padding = ComputePaddingHeightWidth(
      params->stride_height, params->stride_width,
      params->dilation_height_factor, params->dilation_width_factor, height,
      width, filter_height, filter_width, padding, &out_height, &out_width);

  // Note that quantized inference requires that all tensors have their
  // parameters set. This is usually done during quantized training or
  // calibration.
  if (data_type != kTfLiteFloat32) {
    TF_LITE_ENSURE_EQ(context, filter->quantization.type,
                      kTfLiteAffineQuantization);
    const auto* affine_quantization =
        reinterpret_cast<TfLiteAffineQuantization*>(
            filter->quantization.params);
    TF_LITE_ENSURE(context, affine_quantization);
    TF_LITE_ENSURE(context, affine_quantization->scale);
    TF_LITE_ENSURE(context, (affine_quantization->scale->size == 1 ||
                             affine_quantization->scale->size == channels_out));

    data->per_channel_output_multiplier.resize(channels_out);
    data->per_channel_output_shift.resize(channels_out);
    TF_LITE_ENSURE_STATUS(tflite::PopulateConvolutionQuantizationParams(
        context, input, filter, bias, output, params->activation,
        &data->output_multiplier, &data->output_shift,
        &data->output_activation_min, &data->output_activation_max,
        data->per_channel_output_multiplier.data(),
        data->per_channel_output_shift.data(), channels_out));
  }

  if (is_hybrid) {
    const auto* affine_quantization =
        reinterpret_cast<TfLiteAffineQuantization*>(
            filter->quantization.params);
    TF_LITE_ENSURE(context, affine_quantization);
    TF_LITE_ENSURE(context, affine_quantization->scale);
    TF_LITE_ENSURE_EQ(
        context, affine_quantization->scale->size,
        filter->dims->data[affine_quantization->quantized_dimension]);

    int temporaries_count = 0;
    data->input_quantized_index = temporaries_count;
    if (data->input_quantized_id == kTensorNotAllocated) {
      TF_LITE_ENSURE_OK(
          context, context->AddTensors(context, 1, &data->input_quantized_id));
    }
    ++temporaries_count;
    data->scaling_factors_index = temporaries_count;
    if (data->scaling_factors_id == kTensorNotAllocated) {
      TF_LITE_ENSURE_OK(
          context, context->AddTensors(context, 1, &data->scaling_factors_id));
    }
    ++temporaries_count;
    data->input_offset_index = temporaries_count;
    if (data->input_offset_id == kTensorNotAllocated) {
      TF_LITE_ENSURE_OK(
          context, context->AddTensors(context, 1, &data->input_offset_id));
    }
    ++temporaries_count;

    TfLiteIntArrayFree(node->temporaries);
    node->temporaries = TfLiteIntArrayCreate(temporaries_count);

    node->temporaries->data[data->input_quantized_index] =
        data->input_quantized_id;
    TfLiteTensor* input_quantized;
    TF_LITE_ENSURE_OK(
        context, GetTemporarySafe(context, node, data->input_quantized_index,
                                  &input_quantized));
    input_quantized->type = kTfLiteInt8;
    input_quantized->allocation_type = kTfLiteArenaRw;
    if (!TfLiteIntArrayEqual(input_quantized->dims, input->dims)) {
      TfLiteIntArray* input_quantized_size = TfLiteIntArrayCopy(input->dims);
      TF_LITE_ENSURE_OK(context, context->ResizeTensor(context, input_quantized,
                                                       input_quantized_size));
    }
    node->temporaries->data[data->scaling_factors_index] =
        data->scaling_factors_id;
    TfLiteTensor* scaling_factors;
    TF_LITE_ENSURE_OK(
        context, GetTemporarySafe(context, node, data->scaling_factors_index,
                                  &scaling_factors));
    scaling_factors->type = kTfLiteFloat32;
    scaling_factors->allocation_type = kTfLiteArenaRw;
    const int batch_size = SizeOfDimension(input, 0);
    int scaling_dims[1] = {batch_size};
    if (!TfLiteIntArrayEqualsArray(scaling_factors->dims, 1, scaling_dims)) {
      TfLiteIntArray* scaling_factors_size = TfLiteIntArrayCreate(1);
      scaling_factors_size->data[0] = batch_size;
      TF_LITE_ENSURE_OK(context, context->ResizeTensor(context, scaling_factors,
                                                       scaling_factors_size));
    }
    node->temporaries->data[data->input_offset_index] = data->input_offset_id;
    TfLiteTensor* input_offsets;
    TF_LITE_ENSURE_OK(context,
                      GetTemporarySafe(context, node, data->input_offset_index,
                                       &input_offsets));
    input_offsets->type = kTfLiteInt32;
    input_offsets->allocation_type = kTfLiteArenaRw;
    if (!TfLiteIntArrayEqualsArray(input_offsets->dims, 1, scaling_dims)) {
      TfLiteIntArray* input_offsets_size = TfLiteIntArrayCreate(1);
      input_offsets_size->data[0] = batch_size;
      TF_LITE_ENSURE_OK(context, context->ResizeTensor(context, input_offsets,
                                                       input_offsets_size));
    }
  }

  TfLiteIntArray* outputSize = TfLiteIntArrayCreate(4);
  outputSize->data[0] = batches;
  outputSize->data[1] = out_height;
  outputSize->data[2] = out_width;
  outputSize->data[3] = channels_out;
  return context->ResizeTensor(context, output, outputSize);
}