// Copyright (c) the JPEG XL Project Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#include "lib/jxl/dec_noise.h"

#include <cstdint>

#include <cstdlib>

#include <utility>

#undef HWY_TARGET_INCLUDE

#define HWY_TARGET_INCLUDE "lib/jxl/dec_noise.cc"

#include <hwy/foreach_target.h>

#include <hwy/highway.h>

#include "lib/jxl/base/compiler_specific.h"

#include "lib/jxl/base/rect.h"

#include "lib/jxl/frame_dimensions.h"

#include "lib/jxl/image.h"

#include "lib/jxl/xorshift128plus-inl.h"

HWY_BEFORE_NAMESPACE();

namespace jxl {

namespace HWY_NAMESPACE {

// These templates are not found via ADL.

using hwy::HWY_NAMESPACE::Or;

using hwy::HWY_NAMESPACE::ShiftRight;

using hwy::HWY_NAMESPACE::Vec;

using D = HWY_CAPPED(float, kBlockDim);

using DI = hwy::HWY_NAMESPACE::Rebind<int, D>;

using DI8 = hwy::HWY_NAMESPACE::Repartition<uint8_t, D>;

// Converts one vector's worth of random bits to floats in [1, 2).

// NOTE: as the convolution kernel sums to 0, it doesn't matter if inputs are in

// [0, 1) or in [1, 2).

void BitsToFloat(const uint32_t* JXL_RESTRICT random_bits,

                 float* JXL_RESTRICT floats) {

  const HWY_FULL(float) df;

  const HWY_FULL(uint32_t) du;

  const auto bits = Load(du, random_bits);

  // 1.0 + 23 random mantissa bits = [1, 2)

  const auto rand12 = BitCast(df, Or(ShiftRight<9>(bits), Set(du, 0x3F800000)));

  Store(rand12, df, floats);

}

void RandomImage(Xorshift128Plus* rng, const Rect& rect,

                 ImageF* JXL_RESTRICT noise) {

  const size_t xsize = rect.xsize();

  const size_t ysize = rect.ysize();

  // May exceed the vector size, hence we have two loops over x below.

  constexpr size_t kFloatsPerBatch =

      Xorshift128Plus::N * sizeof(uint64_t) / sizeof(float);

  HWY_ALIGN uint64_t batch[Xorshift128Plus::N] = {};

  const HWY_FULL(float) df;

  const size_t N = Lanes(df);

  for (size_t y = 0; y < ysize; ++y) {

    float* JXL_RESTRICT row = rect.Row(noise, y);

    size_t x = 0;

    // Only entire batches (avoids exceeding the image padding).

    for (; x + kFloatsPerBatch < xsize; x += kFloatsPerBatch) {

      rng->Fill(batch);

      for (size_t i = 0; i < kFloatsPerBatch; i += Lanes(df)) {

        BitsToFloat(reinterpret_cast<const uint32_t*>(batch) + i, row + x + i);

      }

    }

    // Any remaining pixels, rounded up to vectors (safe due to padding).

    rng->Fill(batch);

    size_t batch_pos = 0;  // < kFloatsPerBatch

    for (; x < xsize; x += N) {

      BitsToFloat(reinterpret_cast<const uint32_t*>(batch) + batch_pos,

                  row + x);

      batch_pos += N;

    }

  }

}

void Random3Planes(size_t visible_frame_index, size_t nonvisible_frame_index,

                   size_t x0, size_t y0, const std::pair<ImageF*, Rect>& plane0,

                   const std::pair<ImageF*, Rect>& plane1,

                   const std::pair<ImageF*, Rect>& plane2) {

  HWY_ALIGN Xorshift128Plus rng(visible_frame_index, nonvisible_frame_index, x0,

                                y0);

  RandomImage(&rng, plane0.second, plane0.first);

  RandomImage(&rng, plane1.second, plane1.first);

  RandomImage(&rng, plane2.second, plane2.first);

}

// NOLINTNEXTLINE(google-readability-namespace-comments)

}  // namespace HWY_NAMESPACE

}  // namespace jxl

HWY_AFTER_NAMESPACE();

#if HWY_ONCE

namespace jxl {

namespace {

HWY_EXPORT(Random3Planes);

}  // namespace

void PrepareNoiseInput(const PassesDecoderState& dec_state,

                       const FrameDimensions& frame_dim,

                       const FrameHeader& frame_header, size_t group_index,

                       size_t thread) {

  size_t group_dim = frame_dim.group_dim;

  const size_t gx = group_index % frame_dim.xsize_groups;

  const size_t gy = group_index / frame_dim.xsize_groups;

  RenderPipelineInput input =

      dec_state.render_pipeline->GetInputBuffers(group_index, thread);

  size_t noise_c_start =

      3 + frame_header.nonserialized_metadata->m.num_extra_channels;

  // When the color channels are downsampled, we need to generate more noise

  // input for the current group than just the group dimensions.

  std::pair<ImageF*, Rect> rects[3];

  for (size_t iy = 0; iy < frame_header.upsampling; iy++) {

    for (size_t ix = 0; ix < frame_header.upsampling; ix++) {

      for (size_t c = 0; c < 3; c++) {

        auto r = input.GetBuffer(noise_c_start + c);

        rects[c].first = r.first;

        size_t x1 = r.second.x0() + r.second.xsize();

        size_t y1 = r.second.y0() + r.second.ysize();

        rects[c].second =

            Rect(r.second.x0() + ix * group_dim, r.second.y0() + iy * group_dim,

                 group_dim, group_dim, x1, y1);

      }

      HWY_DYNAMIC_DISPATCH(Random3Planes)

      (dec_state.visible_frame_index, dec_state.nonvisible_frame_index,

       (gx * frame_header.upsampling + ix) * group_dim,

       (gy * frame_header.upsampling + iy) * group_dim, rects[0], rects[1],

       rects[2]);

    }

  }

}

void DecodeFloatParam(float precision, float* val, BitReader* br) {

  const int absval_quant = br->ReadFixedBits<10>();

  *val = absval_quant / precision;

}

Status DecodeNoise(BitReader* br, NoiseParams* noise_params) {

  for (float& i : noise_params->lut) {

    DecodeFloatParam(kNoisePrecision, &i, br);

  }

  return true;

}

}  // namespace jxl

#endif  // HWY_ONCE