// Copyright 2019 The libgav1 Authors
//
// 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.

#include "src/utils/block_parameters_holder.h"

#include <algorithm>
#include <atomic>
#include <new>

#include "src/utils/common.h"
#include "src/utils/constants.h"
#include "src/utils/logging.h"
#include "src/utils/types.h"

namespace libgav1 {

bool BlockParametersHolder::Reset(int rows4x4, int columns4x4) {
  rows4x4_ = rows4x4;
  columns4x4_ = columns4x4;
  index_ = 0;
  return block_parameters_cache_.Reset(rows4x4_, columns4x4_) &&
         block_parameters_.Resize(rows4x4_ * columns4x4_);
}

BlockParameters* BlockParametersHolder::Get(int row4x4, int column4x4,
                                            BlockSize block_size) {
  const size_t index = index_.fetch_add(1, std::memory_order_relaxed);
  if (index >= block_parameters_.size()) return nullptr;
  auto& bp = block_parameters_.get()[index];
  if (bp == nullptr) {
    bp.reset(new (std::nothrow) BlockParameters);
    if (bp == nullptr) return nullptr;
  }
  FillCache(row4x4, column4x4, block_size, bp.get());
  return bp.get();
}

void BlockParametersHolder::FillCache(int row4x4, int column4x4,
                                      BlockSize block_size,
                                      BlockParameters* const bp) {
  int rows = std::min(static_cast<int>(kNum4x4BlocksHigh[block_size]),
                      rows4x4_ - row4x4);
  const int columns = std::min(static_cast<int>(kNum4x4BlocksWide[block_size]),
                               columns4x4_ - column4x4);
  auto* bp_dst = &block_parameters_cache_[row4x4][column4x4];
  // Specialize columns cases (values in kNum4x4BlocksWide[]) for better
  // performance.
  if (columns == 1) {
    SetBlock<BlockParameters*>(rows, 1, bp, bp_dst, columns4x4_);
  } else if (columns == 2) {
    SetBlock<BlockParameters*>(rows, 2, bp, bp_dst, columns4x4_);
  } else if (columns == 4) {
    SetBlock<BlockParameters*>(rows, 4, bp, bp_dst, columns4x4_);
  } else if (columns == 8) {
    SetBlock<BlockParameters*>(rows, 8, bp, bp_dst, columns4x4_);
  } else if (columns == 16) {
    SetBlock<BlockParameters*>(rows, 16, bp, bp_dst, columns4x4_);
  } else if (columns == 32) {
    SetBlock<BlockParameters*>(rows, 32, bp, bp_dst, columns4x4_);
  } else {
    do {
      // The following loop has better performance than using std::fill().
      // std::fill() has some overhead in checking zero loop count.
      int x = columns;
      auto* d = bp_dst;
      do {
        *d++ = bp;
      } while (--x != 0);
      bp_dst += columns4x4_;
    } while (--rows != 0);
  }
}

}  // namespace libgav1
