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135 lines
2.9 KiB
C++
135 lines
2.9 KiB
C++
// Copyright 2018 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#pragma once
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#include <array>
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#include <limits>
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#include "Common/BitUtils.h"
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#include "Common/CommonTypes.h"
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#ifdef _MSC_VER
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// MSVC needs a workaround, because its std::numeric_limits<double>::signaling_NaN()
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// will use __builtin_nans, which is improperly handled by the compiler and generates
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// a bad constant. Here we go back to the version MSVC used before the builtin.
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// TODO: Remove this and use numeric_limits directly whenever this bug is fixed.
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// See Visual Studio bug # 128935 "std::numeric_limits<float>::signaling_NaN() is broken"
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#include <ymath.h>
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#endif // _MSC_VER
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namespace Common
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{
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template <typename T>
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constexpr T SNANConstant()
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{
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return std::numeric_limits<T>::signaling_NaN();
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}
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#ifdef _MSC_VER
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// See workaround note above.
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template <>
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constexpr double SNANConstant()
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{
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return (_CSTD _Snan._Double);
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}
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template <>
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constexpr float SNANConstant()
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{
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return (_CSTD _Snan._Float);
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}
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#endif // _MSC_VER
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// The most significant bit of the fraction is an is-quiet bit on all architectures we care about.
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enum : u64
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{
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DOUBLE_SIGN = 0x8000000000000000ULL,
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DOUBLE_EXP = 0x7FF0000000000000ULL,
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DOUBLE_FRAC = 0x000FFFFFFFFFFFFFULL,
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DOUBLE_ZERO = 0x0000000000000000ULL,
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DOUBLE_QBIT = 0x0008000000000000ULL
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};
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enum : u32
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{
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FLOAT_SIGN = 0x80000000,
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FLOAT_EXP = 0x7F800000,
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FLOAT_FRAC = 0x007FFFFF,
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FLOAT_ZERO = 0x00000000
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};
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inline bool IsQNAN(double d)
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{
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const u64 i = BitCast<u64>(d);
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return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_QBIT) == DOUBLE_QBIT);
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}
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inline bool IsSNAN(double d)
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{
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const u64 i = BitCast<u64>(d);
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return ((i & DOUBLE_EXP) == DOUBLE_EXP) && ((i & DOUBLE_FRAC) != DOUBLE_ZERO) &&
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((i & DOUBLE_QBIT) == DOUBLE_ZERO);
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}
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inline float FlushToZero(float f)
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{
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u32 i = BitCast<u32>(f);
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if ((i & FLOAT_EXP) == 0)
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{
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// Turn into signed zero
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i &= FLOAT_SIGN;
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}
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return BitCast<float>(i);
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}
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inline double FlushToZero(double d)
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{
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u64 i = BitCast<u64>(d);
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if ((i & DOUBLE_EXP) == 0)
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{
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// Turn into signed zero
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i &= DOUBLE_SIGN;
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}
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return BitCast<double>(i);
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}
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enum PPCFpClass
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{
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PPC_FPCLASS_QNAN = 0x11,
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PPC_FPCLASS_NINF = 0x9,
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PPC_FPCLASS_NN = 0x8,
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PPC_FPCLASS_ND = 0x18,
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PPC_FPCLASS_NZ = 0x12,
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PPC_FPCLASS_PZ = 0x2,
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PPC_FPCLASS_PD = 0x14,
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PPC_FPCLASS_PN = 0x4,
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PPC_FPCLASS_PINF = 0x5,
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};
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// Uses PowerPC conventions for the return value, so it can be easily
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// used directly in CPU emulation.
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u32 ClassifyDouble(double dvalue);
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// More efficient float version.
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u32 ClassifyFloat(float fvalue);
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struct BaseAndDec
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{
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int m_base;
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int m_dec;
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};
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extern const std::array<BaseAndDec, 32> frsqrte_expected;
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extern const std::array<BaseAndDec, 32> fres_expected;
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// PowerPC approximation algorithms
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double ApproximateReciprocalSquareRoot(double val);
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double ApproximateReciprocal(double val);
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} // namespace Common
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