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 // Copyright (C) 2021 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #ifndef QNUMERIC_H
 #define QNUMERIC_H
 
 #if 0
 #pragma qt_class(QtNumeric)
 #endif
 
 #include <QtCore/qtconfigmacros.h>
 #include <QtCore/qtcoreexports.h>
 #include <QtCore/qtypes.h>
 
 #include <cmath>
 #include <limits>
 #include <type_traits>
 
 // min() and max() may be #defined by windows.h if that is included before, but we need them
 // for std::numeric_limits below. You should not use the min() and max() macros, so we just #undef.
 #ifdef min
 #  undef min
 #  undef max
 #endif
 
 #if defined(Q_CC_MSVC)
 #  include <intrin.h>
 #  include <float.h>
 #  if defined(Q_PROCESSOR_X86_64) || defined(Q_PROCESSOR_ARM_64)
 #    define Q_INTRINSIC_MUL_OVERFLOW64
 #    define Q_UMULH(v1, v2) __umulh(v1, v2);
 #    define Q_SMULH(v1, v2) __mulh(v1, v2);
 #    pragma intrinsic(__umulh)
 #    pragma intrinsic(__mulh)
 #  endif
 #endif
 
 # if defined(Q_OS_INTEGRITY) && defined(Q_PROCESSOR_ARM_64)
 #  include <arm64_ghs.h>
 #  define Q_INTRINSIC_MUL_OVERFLOW64
 #  define Q_UMULH(v1, v2) __MULUH64(v1, v2);
 #  define Q_SMULH(v1, v2) __MULSH64(v1, v2);
 #endif
 
 QT_BEGIN_NAMESPACE
 
 // To match std::is{inf,nan,finite} functions:
 template <typename T>
 constexpr typename std::enable_if<std::is_integral<T>::value, bool>::type
 qIsInf(T) { return false; }
 template <typename T>
 constexpr typename std::enable_if<std::is_integral<T>::value, bool>::type
 qIsNaN(T) { return false; }
 template <typename T>
 constexpr typename std::enable_if<std::is_integral<T>::value, bool>::type
 qIsFinite(T) { return true; }
 
 // Floating-point types (see qfloat16.h for its overloads).
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsInf(double d);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsNaN(double d);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsFinite(double d);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION int qFpClassify(double val);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsInf(float f);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsNaN(float f);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION bool qIsFinite(float f);
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION int qFpClassify(float val);
 
 #if QT_CONFIG(signaling_nan)
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION double qSNaN();
 #endif
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION double qQNaN();
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION double qInf();
 
 Q_CORE_EXPORT quint32 qFloatDistance(float a, float b);
 Q_CORE_EXPORT quint64 qFloatDistance(double a, double b);
 
 #define Q_INFINITY (QT_PREPEND_NAMESPACE(qInf)())
 #if QT_CONFIG(signaling_nan)
 #  define Q_SNAN (QT_PREPEND_NAMESPACE(qSNaN)())
 #endif
 #define Q_QNAN (QT_PREPEND_NAMESPACE(qQNaN)())
 
 // Overflow math.
 // This provides efficient implementations for int, unsigned, qsizetype and
 // size_t. Implementations for 8- and 16-bit types will work but may not be as
 // efficient. Implementations for 64-bit may be missing on 32-bit platforms.
 
 #if (Q_CC_GNU >= 500 || __has_builtin(__builtin_add_overflow)) \
     && !(QT_POINTER_SIZE == 4 && defined(Q_CC_CLANG))
 // GCC 5 and Clang 3.8 have builtins to detect overflows
 // 32 bit Clang has the builtins but tries to link a library which hasn't
 #define Q_INTRINSIC_MUL_OVERFLOW64
 
 template <typename T> inline
 typename std::enable_if_t<std::is_unsigned_v<T> || std::is_signed_v<T>, bool>
 qAddOverflow(T v1, T v2, T *r)
 { return __builtin_add_overflow(v1, v2, r); }
 
 template <typename T> inline
 typename std::enable_if_t<std::is_unsigned_v<T> || std::is_signed_v<T>, bool>
 qSubOverflow(T v1, T v2, T *r)
 { return __builtin_sub_overflow(v1, v2, r); }
 
 template <typename T> inline
 typename std::enable_if_t<std::is_unsigned_v<T> || std::is_signed_v<T>, bool>
 qMulOverflow(T v1, T v2, T *r)
 { return __builtin_mul_overflow(v1, v2, r); }
 
 #else
 // Generic implementations
 
 template <typename T> inline typename std::enable_if_t<std::is_unsigned_v<T>, bool>
 qAddOverflow(T v1, T v2, T *r)
 {
     // unsigned additions are well-defined
     *r = v1 + v2;
     return v1 > T(v1 + v2);
 }
 
 template <typename T> inline typename std::enable_if_t<std::is_signed_v<T>, bool>
 qAddOverflow(T v1, T v2, T *r)
 {
     // Here's how we calculate the overflow:
     // 1) unsigned addition is well-defined, so we can always execute it
     // 2) conversion from unsigned back to signed is implementation-
     //    defined and in the implementations we use, it's a no-op.
     // 3) signed integer overflow happens if the sign of the two input operands
     //    is the same but the sign of the result is different. In other words,
     //    the sign of the result must be the same as the sign of either
     //    operand.
 
     using U = typename std::make_unsigned_t<T>;
     *r = T(U(v1) + U(v2));
 
     // If int is two's complement, assume all integer types are too.
     if (std::is_same_v<int32_t, int>) {
         // Two's complement equivalent (generates slightly shorter code):
         //  x ^ y             is negative if x and y have different signs
         //  x & y             is negative if x and y are negative
         // (x ^ z) & (y ^ z)  is negative if x and z have different signs
         //                    AND y and z have different signs
         return ((v1 ^ *r) & (v2 ^ *r)) < 0;
     }
 
     bool s1 = (v1 < 0);
     bool s2 = (v2 < 0);
     bool sr = (*r < 0);
     return s1 != sr && s2 != sr;
     // also: return s1 == s2 && s1 != sr;
 }
 
 template <typename T> inline typename std::enable_if_t<std::is_unsigned_v<T>, bool>
 qSubOverflow(T v1, T v2, T *r)
 {
     // unsigned subtractions are well-defined
     *r = v1 - v2;
     return v1 < v2;
 }
 
 template <typename T> inline typename std::enable_if_t<std::is_signed_v<T>, bool>
 qSubOverflow(T v1, T v2, T *r)
 {
     // See above for explanation. This is the same with some signs reversed.
     // We can't use qAddOverflow(v1, -v2, r) because it would be UB if
     // v2 == std::numeric_limits<T>::min().
 
     using U = typename std::make_unsigned_t<T>;
     *r = T(U(v1) - U(v2));
 
     if (std::is_same_v<int32_t, int>)
         return ((v1 ^ *r) & (~v2 ^ *r)) < 0;
 
     bool s1 = (v1 < 0);
     bool s2 = !(v2 < 0);
     bool sr = (*r < 0);
     return s1 != sr && s2 != sr;
     // also: return s1 == s2 && s1 != sr;
 }
 
 template <typename T> inline
 typename std::enable_if_t<std::is_unsigned_v<T> || std::is_signed_v<T>, bool>
 qMulOverflow(T v1, T v2, T *r)
 {
     // use the next biggest type
     // Note: for 64-bit systems where __int128 isn't supported, this will cause an error.
     using LargerInt = QIntegerForSize<sizeof(T) * 2>;
     using Larger = typename std::conditional_t<std::is_signed_v<T>,
             typename LargerInt::Signed, typename LargerInt::Unsigned>;
     Larger lr = Larger(v1) * Larger(v2);
     *r = T(lr);
     return lr > (std::numeric_limits<T>::max)() || lr < (std::numeric_limits<T>::min)();
 }
 
 # if defined(Q_INTRINSIC_MUL_OVERFLOW64)
 template <> inline bool qMulOverflow(quint64 v1, quint64 v2, quint64 *r)
 {
     *r = v1 * v2;
     return Q_UMULH(v1, v2);
 }
 template <> inline bool qMulOverflow(qint64 v1, qint64 v2, qint64 *r)
 {
     // This is slightly more complex than the unsigned case above: the sign bit
     // of 'low' must be replicated as the entire 'high', so the only valid
     // values for 'high' are 0 and -1. Use unsigned multiply since it's the same
     // as signed for the low bits and use a signed right shift to verify that
     // 'high' is nothing but sign bits that match the sign of 'low'.
 
     qint64 high = Q_SMULH(v1, v2);
     *r = qint64(quint64(v1) * quint64(v2));
     return (*r >> 63) != high;
 }
 
 #   if defined(Q_OS_INTEGRITY) && defined(Q_PROCESSOR_ARM_64)
 template <> inline bool qMulOverflow(uint64_t v1, uint64_t v2, uint64_t *r)
 {
     return qMulOverflow<quint64>(v1,v2,reinterpret_cast<quint64*>(r));
 }
 
 template <> inline bool qMulOverflow(int64_t v1, int64_t v2, int64_t *r)
 {
     return qMulOverflow<qint64>(v1,v2,reinterpret_cast<qint64*>(r));
 }
 #    endif // OS_INTEGRITY ARM64
 #  endif // Q_INTRINSIC_MUL_OVERFLOW64
 
 #  if defined(Q_CC_MSVC) && defined(Q_PROCESSOR_X86)
 // We can use intrinsics for the unsigned operations with MSVC
 template <> inline bool qAddOverflow(unsigned v1, unsigned v2, unsigned *r)
 { return _addcarry_u32(0, v1, v2, r); }
 
 // 32-bit qMulOverflow is fine with the generic code above
 
 template <> inline bool qAddOverflow(quint64 v1, quint64 v2, quint64 *r)
 {
 #    if defined(Q_PROCESSOR_X86_64)
     return _addcarry_u64(0, v1, v2, reinterpret_cast<unsigned __int64 *>(r));
 #    else
     uint low, high;
     uchar carry = _addcarry_u32(0, unsigned(v1), unsigned(v2), &low);
     carry = _addcarry_u32(carry, v1 >> 32, v2 >> 32, &high);
     *r = (quint64(high) << 32) | low;
     return carry;
 #    endif // !x86-64
 }
 #  endif // MSVC X86
 #endif // !GCC
 
 // Implementations for addition, subtraction or multiplication by a
 // compile-time constant. For addition and subtraction, we simply call the code
 // that detects overflow at runtime. For multiplication, we compare to the
 // maximum possible values before multiplying to ensure no overflow happens.
 
 template <typename T, T V2> bool qAddOverflow(T v1, std::integral_constant<T, V2>, T *r)
 {
     return qAddOverflow(v1, V2, r);
 }
 
 template <auto V2, typename T> bool qAddOverflow(T v1, T *r)
 {
     return qAddOverflow(v1, std::integral_constant<T, V2>{}, r);
 }
 
 template <typename T, T V2> bool qSubOverflow(T v1, std::integral_constant<T, V2>, T *r)
 {
     return qSubOverflow(v1, V2, r);
 }
 
 template <auto V2, typename T> bool qSubOverflow(T v1, T *r)
 {
     return qSubOverflow(v1, std::integral_constant<T, V2>{}, r);
 }
 
 template <typename T, T V2> bool qMulOverflow(T v1, std::integral_constant<T, V2>, T *r)
 {
     // Runtime detection for anything smaller than or equal to a register
     // width, as most architectures' multiplication instructions actually
     // produce a result twice as wide as the input registers, allowing us to
     // efficiently detect the overflow.
     if constexpr (sizeof(T) <= sizeof(qregisteruint)) {
         return qMulOverflow(v1, V2, r);
 
 #ifdef Q_INTRINSIC_MUL_OVERFLOW64
     } else if constexpr (sizeof(T) <= sizeof(quint64)) {
         // If we have intrinsics detecting overflow of 64-bit multiplications,
         // then detect overflows through them up to 64 bits.
         return qMulOverflow(v1, V2, r);
 #endif
 
     } else if constexpr (V2 == 0 || V2 == 1) {
         // trivial cases (and simplify logic below due to division by zero)
         *r = v1 * V2;
         return false;
     } else if constexpr (V2 == -1) {
         // multiplication by -1 is valid *except* for signed minimum values
         // (necessary to avoid diving min() by -1, which is an overflow)
         if (v1 < 0 && v1 == (std::numeric_limits<T>::min)())
             return true;
         *r = -v1;
         return false;
     } else {
         // For 64-bit multiplications on 32-bit platforms, let's instead compare v1
         // against the bounds that would overflow.
         constexpr T Highest = (std::numeric_limits<T>::max)() / V2;
         constexpr T Lowest = (std::numeric_limits<T>::min)() / V2;
         if constexpr (Highest > Lowest) {
             if (v1 > Highest || v1 < Lowest)
                 return true;
         } else {
             // this can only happen if V2 < 0
             static_assert(V2 < 0);
             if (v1 > Lowest || v1 < Highest)
                 return true;
         }
 
         *r = v1 * V2;
         return false;
     }
 }
 
 template <auto V2, typename T> bool qMulOverflow(T v1, T *r)
 {
     if constexpr (V2 == 2)
         return qAddOverflow(v1, v1, r);
     return qMulOverflow(v1, std::integral_constant<T, V2>{}, r);
 }
 
 template <typename T>
 constexpr inline T qAbs(const T &t) { return t >= 0 ? t : -t; }
 
 // gcc < 10 doesn't have __has_builtin
 #if defined(Q_PROCESSOR_ARM_64) && (__has_builtin(__builtin_round) || defined(Q_CC_GNU)) && !defined(Q_CC_CLANG)
 // ARM64 has a single instruction that can do C++ rounding with conversion to integer.
 // Note current clang versions have non-constexpr __builtin_round, ### allow clang this path when they fix it.
 constexpr inline int qRound(double d)
 { return int(__builtin_round(d)); }
 constexpr inline int qRound(float f)
 { return int(__builtin_roundf(f)); }
 constexpr inline qint64 qRound64(double d)
 { return qint64(__builtin_round(d)); }
 constexpr inline qint64 qRound64(float f)
 { return qint64(__builtin_roundf(f)); }
 #elif defined(__SSE2__) && (__has_builtin(__builtin_copysign) || defined(Q_CC_GNU))
 // SSE has binary operations directly on floating point making copysign fast
 constexpr inline int qRound(double d)
 { return int(d + __builtin_copysign(0.5, d)); }
 constexpr inline int qRound(float f)
 { return int(f + __builtin_copysignf(0.5f, f)); }
 constexpr inline qint64 qRound64(double d)
 { return qint64(d + __builtin_copysign(0.5, d)); }
 constexpr inline qint64 qRound64(float f)
 { return qint64(f + __builtin_copysignf(0.5f, f)); }
 #else
 constexpr inline int qRound(double d)
 { return d >= 0.0 ? int(d + 0.5) : int(d - 0.5); }
 constexpr inline int qRound(float d)
 { return d >= 0.0f ? int(d + 0.5f) : int(d - 0.5f); }
 
 constexpr inline qint64 qRound64(double d)
 { return d >= 0.0 ? qint64(d + 0.5) : qint64(d - 0.5); }
 constexpr inline qint64 qRound64(float d)
 { return d >= 0.0f ? qint64(d + 0.5f) : qint64(d - 0.5f); }
 #endif
 
 namespace QtPrivate {
 template <typename T>
 constexpr inline const T &min(const T &a, const T &b) { return (a < b) ? a : b; }
 }
 
 [[nodiscard]] constexpr bool qFuzzyCompare(double p1, double p2)
 {
     return (qAbs(p1 - p2) * 1000000000000. <= QtPrivate::min(qAbs(p1), qAbs(p2)));
 }
 
 [[nodiscard]] constexpr bool qFuzzyCompare(float p1, float p2)
 {
     return (qAbs(p1 - p2) * 100000.f <= QtPrivate::min(qAbs(p1), qAbs(p2)));
 }
 
 [[nodiscard]] constexpr bool qFuzzyIsNull(double d)
 {
     return qAbs(d) <= 0.000000000001;
 }
 
 [[nodiscard]] constexpr bool qFuzzyIsNull(float f)
 {
     return qAbs(f) <= 0.00001f;
 }
 
 QT_WARNING_PUSH
 QT_WARNING_DISABLE_FLOAT_COMPARE
 
 [[nodiscard]] constexpr bool qIsNull(double d) noexcept
 {
     return d == 0.0;
 }
 
 [[nodiscard]] constexpr bool qIsNull(float f) noexcept
 {
     return f == 0.0f;
 }
 
 QT_WARNING_POP
 
 inline int qIntCast(double f) { return int(f); }
 inline int qIntCast(float f) { return int(f); }
 
 QT_END_NAMESPACE
 
 #endif // QNUMERIC_H

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