Provides 16-bit floating point support.
The
qfloat16class provides support for half-precision (16-bit) floating point data. It is fully compliant with IEEE 754 as a storage type. This implies that any arithmetic operation on aqfloat16instance results in the value first being converted to afloat. This conversion to and fromfloatis performed by hardware when possible, but on processors that do not natively support half-precision, the conversion is performed through a sequence of lookup table operations.
qfloat16should be treated as if it were a POD (plain old data) type. Consequently, none of the supported operations need any elaboration beyond stating that it supports all arithmetic operators incident to floating point types.Note
On x86 and x86-64 that to get hardware accelerated conversions you must compile with F16C or AVX2 enabled, or use
qFloatToFloat16()andqFloatFromFloat16()which will detect F16C at runtime.Defining this macro disables the arithmetic operators for qfloat16.
This is only necessary on Visual Studio 2017 (and earlier) when including
<QFloat16>and<bitset>in the same translation unit, which would otherwise cause a compilation error due to a toolchain bug (see [QTBUG-72073]).Returns a qfloat16 with the sign of
signbut the rest of its value taken from this qfloat16. Serves as qfloat16’s equivalent of std::copysign().Implements
qFpClassify()for qfloat16.See also
qFpClassify()Returns
trueif thisqfloat16value is finite and in normal form.See also
qFpClassify()Converts
lenqfloat16 frominto floats and stores them inout. Bothinandoutmust havelenallocated entries.This function is faster than converting values one by one, and will do runtime F16C detection on x86 and x86-64 hardware.
Converts
lenfloats frominto qfloat16 and stores them inout. Bothinandoutmust havelenallocated entries.This function is faster than converting values one by one, and will do runtime F16C detection on x86 and x86-64 hardware.
Compares the floating point value
p1andp2and returnstrueif they are considered equal, otherwisefalse.The two numbers are compared in a relative way, where the exactness is stronger the smaller the numbers are.
Returns true if the
qfloat16fis a finite number.See also
qIsFiniteReturns true if the
qfloat16fis equivalent to infinity.See also
qIsInfReturns true if the
qfloat16fis not a number (NaN).See also
qIsNaNRounds
valueto the nearest integer.See also
qRoundRounds
valueto the nearest 64-bit integer.See also
qRound64
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