| 1 | // Copyright (C) 2024 The Qt Company Ltd. |
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| 2 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only |
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| 3 | #ifndef Q26NUMERIC_H |
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| 4 | #define Q26NUMERIC_H |
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| 5 | |
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| 6 | #include <QtCore/qglobal.h> |
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| 7 | |
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| 8 | // |
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| 9 | // W A R N I N G |
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| 10 | // ------------- |
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| 11 | // |
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| 12 | // This file is not part of the Qt API. Types and functions defined in this |
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| 13 | // file can reliably be replaced by their std counterparts, once available. |
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| 14 | // You may use these definitions in your own code, but be aware that we |
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| 15 | // will remove them once Qt depends on the C++ version that supports |
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| 16 | // them in namespace std. There will be NO deprecation warning, the |
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| 17 | // definitions will JUST go away. |
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| 18 | // |
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| 19 | // If you can't agree to these terms, don't use these definitions! |
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| 20 | // |
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| 21 | // We mean it. |
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| 22 | // |
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| 23 | |
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| 24 | #include <numeric> |
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| 25 | #include <limits> |
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| 26 | #include <type_traits> |
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| 27 | |
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| 28 | QT_BEGIN_NAMESPACE |
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| 29 | |
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| 30 | namespace q26 { |
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| 31 | |
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| 32 | // Like std::saturate_cast |
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| 33 | #ifdef __cpp_lib_saturation_arithmetic |
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| 34 | using std::saturate_cast; |
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| 35 | #else |
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| 36 | template <typename To, typename From> |
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| 37 | constexpr auto saturate_cast(From x) |
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| 38 | { |
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| 39 | static_assert(std::is_integral_v<To>); |
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| 40 | static_assert(std::is_integral_v<From>); |
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| 41 | |
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| 42 | [[maybe_unused]] |
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| 43 | constexpr auto Lo = (std::numeric_limits<To>::min)(); |
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| 44 | constexpr auto Hi = (std::numeric_limits<To>::max)(); |
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| 45 | |
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| 46 | if constexpr (std::is_signed_v<From> == std::is_signed_v<To>) { |
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| 47 | // same signedness, we can accept regular integer conversion rules |
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| 48 | return x < Lo ? Lo : |
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| 49 | x > Hi ? Hi : |
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| 50 | /*else*/ To(x); |
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| 51 | } else { |
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| 52 | if constexpr (std::is_signed_v<From>) { // ie. !is_signed_v<To> |
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| 53 | if (x < From{0}) |
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| 54 | return To{0}; |
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| 55 | } |
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| 56 | |
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| 57 | // from here on, x >= 0 |
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| 58 | using FromU = std::make_unsigned_t<From>; |
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| 59 | using ToU = std::make_unsigned_t<To>; |
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| 60 | return FromU(x) > ToU(Hi) ? Hi : To(x); // assumes Hi >= 0 |
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| 61 | } |
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| 62 | } |
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| 63 | #endif // __cpp_lib_saturation_arithmetic |
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| 64 | |
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| 65 | } // namespace q26 |
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| 66 | |
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| 67 | QT_END_NAMESPACE |
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| 68 | |
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| 69 | #endif /* Q26NUMERIC_H */ |
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| 70 | |
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