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// Copyright 2008 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <algorithm>
#include <bit>
#include <cmath>
#include <limits>
#include <type_traits>
#include "Common/CommonTypes.h"
namespace MathUtil
{
constexpr double TAU = 6.2831853071795865;
constexpr double PI = TAU / 2;
constexpr double GRAVITY_ACCELERATION = 9.80665;
template <typename T>
constexpr auto Sign(const T& val) -> decltype((T{} < val) - (val < T{}))
{
return (T{} < val) - (val < T{});
}
template <typename T, typename F>
constexpr auto Lerp(const T& x, const T& y, const F& a) -> decltype(x + (y - x) * a)
{
return x + (y - x) * a;
}
// Casts the specified value to a Dest. The value will be clamped to fit in the destination type.
// Warning: The result of SaturatingCast(NaN) is undefined.
template <typename Dest, typename T>
constexpr Dest SaturatingCast(T value)
{
static_assert(std::is_integral<Dest>());
[[maybe_unused]] constexpr Dest lo = std::numeric_limits<Dest>::lowest();
constexpr Dest hi = std::numeric_limits<Dest>::max();
// T being a signed integer and Dest unsigned is a problematic case because the value will
// be converted into an unsigned integer, and u32(...) < 0 is always false.
if constexpr (std::is_integral<T>() && std::is_signed<T>() && std::is_unsigned<Dest>())
{
static_assert(lo == 0);
if (value < 0)
return lo;
// Now that we got rid of negative values, we can safely cast value to an unsigned T
// since unsigned T can represent any positive value signed T could represent.
// The compiler will then promote the LHS or the RHS if necessary.
if (std::make_unsigned_t<T>(value) > hi)
return hi;
}
else if constexpr (std::is_integral<T>() && std::is_unsigned<T>() && std::is_signed<Dest>())
{
// value and hi will never be negative, and hi is representable as an unsigned Dest.
if (value > std::make_unsigned_t<Dest>(hi))
return hi;
}
else
{
// Do not use std::clamp or a similar function here to avoid overflow.
// For example, if Dest = s64 and T = int, we want integer promotion to convert value to a s64
// instead of changing lo or hi into an int.
if (value < lo)
return lo;
if (value > hi)
return hi;
}
return static_cast<Dest>(value);
}
template <typename T>
constexpr bool IsPow2(T imm)
{
return imm > 0 && (imm & (imm - 1)) == 0;
}
constexpr u32 NextPowerOf2(u32 value)
{
--value;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
++value;
return value;
}
template <class T>
struct Rectangle
{
T left{};
T top{};
T right{};
T bottom{};
constexpr Rectangle() = default;
constexpr Rectangle(T theLeft, T theTop, T theRight, T theBottom)
: left(theLeft), top(theTop), right(theRight), bottom(theBottom)
{
}
constexpr bool operator==(const Rectangle& r) const
{
return left == r.left && top == r.top && right == r.right && bottom == r.bottom;
}
constexpr T GetWidth() const { return GetDistance(left, right); }
constexpr T GetHeight() const { return GetDistance(top, bottom); }
// If the rectangle is in a coordinate system with a lower-left origin, use
// this Clamp.
void ClampLL(T x1, T y1, T x2, T y2)
{
left = std::clamp(left, x1, x2);
right = std::clamp(right, x1, x2);
top = std::clamp(top, y2, y1);
bottom = std::clamp(bottom, y2, y1);
}
// If the rectangle is in a coordinate system with an upper-left origin,
// use this Clamp.
void ClampUL(T x1, T y1, T x2, T y2)
{
left = std::clamp(left, x1, x2);
right = std::clamp(right, x1, x2);
top = std::clamp(top, y1, y2);
bottom = std::clamp(bottom, y1, y2);
}
private:
constexpr T GetDistance(T a, T b) const
{
if constexpr (std::is_unsigned<T>())
return b > a ? b - a : a - b;
else
return std::abs(b - a);
}
};
template <typename T>
class RunningMean
{
public:
constexpr void Clear() { *this = {}; }
constexpr void Push(T x) { m_mean = m_mean + (x - m_mean) / ++m_count; }
constexpr size_t Count() const { return m_count; }
constexpr T Mean() const { return m_mean; }
private:
size_t m_count = 0;
T m_mean{};
};
template <typename T>
class RunningVariance
{
public:
constexpr void Clear() { *this = {}; }
constexpr void Push(T x)
{
const auto old_mean = m_running_mean.Mean();
m_running_mean.Push(x);
m_variance += (x - old_mean) * (x - m_running_mean.Mean());
}
constexpr size_t Count() const { return m_running_mean.Count(); }
constexpr T Mean() const { return m_running_mean.Mean(); }
constexpr T Variance() const { return m_variance / (Count() - 1); }
T StandardDeviation() const { return std::sqrt(Variance()); }
constexpr T PopulationVariance() const { return m_variance / Count(); }
T PopulationStandardDeviation() const { return std::sqrt(PopulationVariance()); }
private:
RunningMean<T> m_running_mean;
T m_variance{};
};
// Rounds down. 0 -> undefined
constexpr int IntLog2(u64 val)
{
return 63 - std::countl_zero(val);
}
} // namespace MathUtil
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