libgav1/src/dsp/x86/average_blend_sse4.cc

// 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/dsp/average_blend.h"
#include "src/dsp/dsp.h"

#if LIBGAV1_ENABLE_SSE4_1

#include <xmmintrin.h>

#include <cassert>
#include <cstddef>
#include <cstdint>

#include "src/dsp/x86/common_sse4.h"
#include "src/utils/common.h"

namespace libgav1 {
namespace dsp {
namespace {

constexpr int kBitdepth8 = 8;
constexpr int kInterPostRoundBit = 4;
// An offset to cancel offsets used in compound predictor generation that
// make intermediate computations non negative.
const __m128i kCompoundRoundOffset =
    _mm_set1_epi16((2 << (kBitdepth8 + 4)) + (2 << (kBitdepth8 + 3)));

inline void AverageBlend4Row(const uint16_t* prediction_0,
                             const uint16_t* prediction_1, uint8_t* dest) {
  const __m128i pred_0 = LoadLo8(prediction_0);
  const __m128i pred_1 = LoadLo8(prediction_1);
  __m128i res = _mm_add_epi16(pred_0, pred_1);
  res = _mm_sub_epi16(res, kCompoundRoundOffset);
  res = RightShiftWithRounding_S16(res, kInterPostRoundBit + 1);
  Store4(dest, _mm_packus_epi16(res, res));
}

inline void AverageBlend8Row(const uint16_t* prediction_0,
                             const uint16_t* prediction_1, uint8_t* dest) {
  const __m128i pred_0 = LoadUnaligned16(prediction_0);
  const __m128i pred_1 = LoadUnaligned16(prediction_1);
  __m128i res = _mm_add_epi16(pred_0, pred_1);
  res = _mm_sub_epi16(res, kCompoundRoundOffset);
  res = RightShiftWithRounding_S16(res, kInterPostRoundBit + 1);
  StoreLo8(dest, _mm_packus_epi16(res, res));
}

inline void AverageBlendLargeRow(const uint16_t* prediction_0,
                                 const uint16_t* prediction_1, const int width,
                                 uint8_t* dest) {
  int x = 0;
  do {
    const __m128i pred_00 = LoadUnaligned16(&prediction_0[x]);
    const __m128i pred_01 = LoadUnaligned16(&prediction_1[x]);
    __m128i res0 = _mm_add_epi16(pred_00, pred_01);
    res0 = _mm_sub_epi16(res0, kCompoundRoundOffset);
    res0 = RightShiftWithRounding_S16(res0, kInterPostRoundBit + 1);
    const __m128i pred_10 = LoadUnaligned16(&prediction_0[x + 8]);
    const __m128i pred_11 = LoadUnaligned16(&prediction_1[x + 8]);
    __m128i res1 = _mm_add_epi16(pred_10, pred_11);
    res1 = _mm_sub_epi16(res1, kCompoundRoundOffset);
    res1 = RightShiftWithRounding_S16(res1, kInterPostRoundBit + 1);
    StoreUnaligned16(dest + x, _mm_packus_epi16(res0, res1));
    x += 16;
  } while (x < width);
}

void AverageBlend_SSE4_1(const uint16_t* prediction_0,
                         const ptrdiff_t prediction_stride_0,
                         const uint16_t* prediction_1,
                         const ptrdiff_t prediction_stride_1, const int width,
                         const int height, void* const dest,
                         const ptrdiff_t dest_stride) {
  auto* dst = static_cast<uint8_t*>(dest);
  int y = height;

  if (width == 4) {
    do {
      AverageBlend4Row(prediction_0, prediction_1, dst);
      dst += dest_stride;
      prediction_0 += prediction_stride_0;
      prediction_1 += prediction_stride_1;

      AverageBlend4Row(prediction_0, prediction_1, dst);
      dst += dest_stride;
      prediction_0 += prediction_stride_0;
      prediction_1 += prediction_stride_1;

      y -= 2;
    } while (y != 0);
    return;
  }

  if (width == 8) {
    do {
      AverageBlend8Row(prediction_0, prediction_1, dst);
      dst += dest_stride;
      prediction_0 += prediction_stride_0;
      prediction_1 += prediction_stride_1;

      AverageBlend8Row(prediction_0, prediction_1, dst);
      dst += dest_stride;
      prediction_0 += prediction_stride_0;
      prediction_1 += prediction_stride_1;

      y -= 2;
    } while (y != 0);
    return;
  }

  do {
    AverageBlendLargeRow(prediction_0, prediction_1, width, dst);
    dst += dest_stride;
    prediction_0 += prediction_stride_0;
    prediction_1 += prediction_stride_1;

    AverageBlendLargeRow(prediction_0, prediction_1, width, dst);
    dst += dest_stride;
    prediction_0 += prediction_stride_0;
    prediction_1 += prediction_stride_1;

    y -= 2;
  } while (y != 0);
}

void Init8bpp() {
  Dsp* const dsp = dsp_internal::GetWritableDspTable(8);
  assert(dsp != nullptr);
#if DSP_ENABLED_8BPP_SSE4_1(AverageBlend)
  dsp->average_blend = AverageBlend_SSE4_1;
#endif
}

}  // namespace

void AverageBlendInit_SSE4_1() { Init8bpp(); }

}  // namespace dsp
}  // namespace libgav1

#else   // !LIBGAV1_ENABLE_SSE4_1

namespace libgav1 {
namespace dsp {

void AverageBlendInit_SSE4_1() {}

}  // namespace dsp
}  // namespace libgav1
#endif  // LIBGAV1_ENABLE_SSE4_1