dolphin/Source/Core/Common/FloatUtils.h

104 lines
2.2 KiB
C++

// Copyright 2018 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <array>
#include <limits>
#include "Common/BitUtils.h"
#include "Common/CommonTypes.h"
namespace Common
{
template <typename T>
constexpr T SNANConstant()
{
return std::numeric_limits<T>::signaling_NaN();
}
// The most significant bit of the fraction is an is-quiet bit on all architectures we care about.
enum : u64
{
DOUBLE_SIGN = 0x8000000000000000ULL,
DOUBLE_EXP = 0x7FF0000000000000ULL,
DOUBLE_FRAC = 0x000FFFFFFFFFFFFFULL,
DOUBLE_ZERO = 0x0000000000000000ULL,
DOUBLE_QBIT = 0x0008000000000000ULL
};
enum : u32
{
FLOAT_SIGN = 0x80000000,
FLOAT_EXP = 0x7F800000,
FLOAT_FRAC = 0x007FFFFF,
FLOAT_ZERO = 0x00000000
};
inline bool IsQNAN(double d)
{
const u64 i = BitCast<u64>(d);
return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_QBIT) == DOUBLE_QBIT);
}
inline bool IsSNAN(double d)
{
const u64 i = BitCast<u64>(d);
return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_FRAC) != DOUBLE_ZERO) &&
((i & DOUBLE_QBIT) == DOUBLE_ZERO);
}
inline float FlushToZero(float f)
{
u32 i = BitCast<u32>(f);
if ((i & FLOAT_EXP) == 0)
{
// Turn into signed zero
i &= FLOAT_SIGN;
}
return BitCast<float>(i);
}
inline double FlushToZero(double d)
{
u64 i = BitCast<u64>(d);
if ((i & DOUBLE_EXP) == 0)
{
// Turn into signed zero
i &= DOUBLE_SIGN;
}
return BitCast<double>(i);
}
enum PPCFpClass
{
PPC_FPCLASS_QNAN = 0x11,
PPC_FPCLASS_NINF = 0x9,
PPC_FPCLASS_NN = 0x8,
PPC_FPCLASS_ND = 0x18,
PPC_FPCLASS_NZ = 0x12,
PPC_FPCLASS_PZ = 0x2,
PPC_FPCLASS_PD = 0x14,
PPC_FPCLASS_PN = 0x4,
PPC_FPCLASS_PINF = 0x5,
};
// Uses PowerPC conventions for the return value, so it can be easily
// used directly in CPU emulation.
u32 ClassifyDouble(double dvalue);
u32 ClassifyFloat(float fvalue);
struct BaseAndDec
{
int m_base;
int m_dec;
};
extern const std::array<BaseAndDec, 32> frsqrte_expected;
extern const std::array<BaseAndDec, 32> fres_expected;
// PowerPC approximation algorithms
double ApproximateReciprocalSquareRoot(double val);
double ApproximateReciprocal(double val);
} // namespace Common