/* Copyright 2019 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_KERNELS_INTERNAL_REFERENCE_CONCATENATION_H_
#define TENSORFLOW_LITE_KERNELS_INTERNAL_REFERENCE_CONCATENATION_H_

#include "tensorflow/lite/kernels/internal/common.h"
#include "tensorflow/lite/kernels/internal/compatibility.h"
#include "tensorflow/lite/kernels/internal/cppmath.h"
#include "tensorflow/lite/kernels/internal/types.h"

namespace tflite {
namespace reference_ops {

template <typename Scalar>
inline void Concatenation(const ConcatenationParams& params,
                          const RuntimeShape* const* input_shapes,
                          const Scalar* const* input_data,
                          const RuntimeShape& output_shape,
                          Scalar* output_data) {
  int axis = params.axis;
  int inputs_count = params.inputs_count;
  const int concat_dimensions = output_shape.DimensionsCount();
  TFLITE_DCHECK_LT(axis, concat_dimensions);

  int64_t concat_size = 0;
  for (int i = 0; i < inputs_count; i++) {
    TFLITE_DCHECK_EQ(input_shapes[i]->DimensionsCount(), concat_dimensions);
    for (int j = 0; j < concat_dimensions; j++) {
      if (j != axis) {
        MatchingDim(*input_shapes[i], j, output_shape, j);
      }
    }
    concat_size += input_shapes[i]->Dims(axis);
  }
  TFLITE_DCHECK_EQ(concat_size, output_shape.Dims(axis));
  int64_t outer_size = 1;
  for (int i = 0; i < axis; ++i) {
    outer_size *= output_shape.Dims(i);
  }
  // For all input arrays,
  // FlatSize() = outer_size * Dims(axis) * base_inner_size;
  int64_t base_inner_size = 1;
  for (int i = axis + 1; i < concat_dimensions; ++i) {
    base_inner_size *= output_shape.Dims(i);
  }

  Scalar* output_ptr = output_data;
  for (int k = 0; k < outer_size; k++) {
    for (int i = 0; i < inputs_count; ++i) {
      const int copy_size = input_shapes[i]->Dims(axis) * base_inner_size;
      const Scalar* input_ptr = input_data[i] + k * copy_size;
      memcpy(output_ptr, input_ptr, copy_size * sizeof(Scalar));
      output_ptr += copy_size;
    }
  }
}

// TODO(prabhumk): This is the same as the optimized implementation.
// TODO(prabhumk): The quantized implementation of concatentation isn't fully
// quantized as it takes scale as a floating point value. This should be fixed
// when optimizng this routine further.
inline void ConcatenationWithScaling(const ConcatenationParams& params,
                                     const RuntimeShape* const* input_shapes,
                                     const uint8_t* const* input_data,
                                     const RuntimeShape& output_shape,
                                     uint8_t* output_data) {
  int axis = params.axis;
  const int32_t* input_zeropoint = params.input_zeropoint;
  const float* input_scale = params.input_scale;
  int inputs_count = params.inputs_count;
  const int32_t output_zeropoint = params.output_zeropoint;
  const float output_scale = params.output_scale;

  const int concat_dimensions = output_shape.DimensionsCount();
  TFLITE_DCHECK_LT(axis, concat_dimensions);

  int64_t concat_size = 0;
  for (int i = 0; i < inputs_count; i++) {
    TFLITE_DCHECK_EQ(input_shapes[i]->DimensionsCount(), concat_dimensions);
    for (int j = 0; j < concat_dimensions; j++) {
      if (j != axis) {
        MatchingDim(*input_shapes[i], j, output_shape, j);
      }
    }
    concat_size += input_shapes[i]->Dims(axis);
  }
  TFLITE_DCHECK_EQ(concat_size, output_shape.Dims(axis));
  int64_t outer_size = 1;
  for (int i = 0; i < axis; ++i) {
    outer_size *= output_shape.Dims(i);
  }
  // For all input arrays,
  // FlatSize() = outer_size * Dims(axis) * base_inner_size;
  int64_t base_inner_size = 1;
  for (int i = axis + 1; i < concat_dimensions; ++i) {
    base_inner_size *= output_shape.Dims(i);
  }

  const float inverse_output_scale = 1.f / output_scale;
  uint8_t* output_ptr = output_data;
  for (int k = 0; k < outer_size; k++) {
    for (int i = 0; i < inputs_count; ++i) {
      const int copy_size = input_shapes[i]->Dims(axis) * base_inner_size;
      const uint8_t* input_ptr = input_data[i] + k * copy_size;
      if (input_zeropoint[i] == output_zeropoint &&
          input_scale[i] == output_scale) {
        memcpy(output_ptr, input_ptr, copy_size);
      } else {
        const float scale = input_scale[i] * inverse_output_scale;
        const float bias = -input_zeropoint[i] * scale;
        for (int j = 0; j < copy_size; ++j) {
          const int32_t value = static_cast<int32_t>(tflite::TfLiteRound(
                                    input_ptr[j] * scale + bias)) +
                                output_zeropoint;
          output_ptr[j] = static_cast<uint8_t>(
              std::max<int32_t>(std::min<int32_t>(255, value), 0));
        }
      }
      output_ptr += copy_size;
    }
  }
}

}  // namespace reference_ops
}  // namespace tflite

#endif  // TENSORFLOW_LITE_KERNELS_INTERNAL_REFERENCE_CONCATENATION_H_