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46 lines
1.1 KiB
C
46 lines
1.1 KiB
C
/*
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* PROJECT: ReactOS CRT
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* LICENSE: MIT (https://spdx.org/licenses/MIT)
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* PURPOSE: Implementation of _dclass.
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* COPYRIGHT: Copyright 2025 Timo Kreuzer <timo.kreuzer@reactos.org>
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*/
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#include <math.h>
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#include <stdint.h>
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#if defined(_MSC_VER) && (_MSC_VER >= 1922)
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_Check_return_ short __cdecl _dclass(_In_ double _X);
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#pragma function(_dclass)
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#endif
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//
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// Returns the floating-point classification of _X.
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//
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// FP_NAN - A quiet, signaling, or indeterminate NaN
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// FP_INFINITE - A positive or negative infinity
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// FP_NORMAL - A positive or negative normalized non-zero value
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// FP_SUBNORMAL - A positive or negative subnormal (denormalized) value
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// FP_ZERO - A positive or negative zero value
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//
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_Check_return_
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short
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__cdecl
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_dclass(_In_ double _X)
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{
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union { double f; uint64_t ui64; } u = { _X };
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uint64_t e = u.ui64 & 0x7FF0000000000000ull;
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uint64_t m = u.ui64 & 0x000FFFFFFFFFFFFFull;
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if (e == 0x7FF0000000000000ull)
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{
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return m ? FP_NAN : FP_INFINITE;
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}
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else if (e == 0)
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{
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return m ? FP_SUBNORMAL : FP_ZERO;
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}
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else
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{
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return FP_NORMAL;
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}
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}
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