// 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.

#ifndef LIB_JXL_NOISE_H_

#define LIB_JXL_NOISE_H_

// Noise parameters shared by encoder/decoder.

#include <stddef.h>

#include <algorithm>

#include <cmath>

#include <utility>

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

namespace jxl {

const float kNoisePrecision = 1 << 10;

struct NoiseParams {

  // LUT index is an intensity of pixel / mean intensity of patch

  static constexpr size_t kNumNoisePoints = 8;

  float lut[kNumNoisePoints];

  void Clear() {

    for (float& i : lut) i = 0.f;

  }

  bool HasAny() const {

    for (float i : lut) {

      if (std::abs(i) > 1e-3f) return true;

    }

    return false;

  }

};

static inline std::pair<int, float> IndexAndFrac(float x) {

  constexpr size_t kScaleNumerator = NoiseParams::kNumNoisePoints - 2;

  // TODO: instead of 1, this should be a proper Y range.

  constexpr float kScale = kScaleNumerator / 1;

  float scaled_x = std::max(0.f, x * kScale);

  float floor_x;

  float frac_x = std::modf(scaled_x, &floor_x);

  if (JXL_UNLIKELY(scaled_x >= kScaleNumerator + 1)) {

    floor_x = kScaleNumerator;

    frac_x = 1.f;

  }

  return std::make_pair(static_cast<int>(floor_x), frac_x);

}

struct NoiseLevel {

  float noise_level;

  float intensity;

};

}  // namespace jxl

#endif  // LIB_JXL_NOISE_H_