| 1 | /* |
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| 2 | Approximated math functions used into conversions. |
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| 3 | |
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| 4 | SPDX-FileCopyrightText: Edward Kmett |
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| 5 | SPDX-FileCopyrightText: 2023 Mirco Miranda <mircomir@outlook.com> |
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| 6 | |
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| 7 | SPDX-License-Identifier: BSD-3-Clause |
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| 8 | */ |
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| 9 | #ifndef FASTMATH_P_H |
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| 10 | #define FASTMATH_P_H |
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| 11 | |
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| 12 | #include <QtGlobal> |
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| 13 | |
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| 14 | /*! |
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| 15 | * \brief fastPow |
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| 16 | * Based on Edward Kmett code released into the public domain. |
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| 17 | * See also: https://github.com/ekmett/approximate |
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| 18 | */ |
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| 19 | inline double fastPow(double x, double y) |
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| 20 | { |
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| 21 | union { |
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| 22 | double d; |
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| 23 | qint32 i[2]; |
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| 24 | } u = {.d: x}; |
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| 25 | #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN |
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| 26 | u.i[1] = qint32(y * (u.i[1] - 1072632447) + 1072632447); |
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| 27 | u.i[0] = 0; |
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| 28 | #else // never tested |
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| 29 | u.i[0] = qint32(y * (u.i[0] - 1072632447) + 1072632447); |
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| 30 | u.i[1] = 0; |
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| 31 | #endif |
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| 32 | return u.d; |
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| 33 | } |
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| 34 | |
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| 35 | #endif // FASTMATH_P_H |
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| 36 | |
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