assimp/contrib/cppunit-1.12.1/include/cppunit/portability/FloatingPoint.h

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#ifndef CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED
#define CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED
#include <cppunit/Portability.h>
#include <math.h>
CPPUNIT_NS_BEGIN
/// \brief Tests if a floating-point is a NaN.
// According to IEEE-754 floating point standard,
// (see e.g. page 8 of
// http://www.cs.berkeley.edu/~wkahan/ieee754status/ieee754.ps)
// all comparisons with NaN are false except "x != x", which is true.
//
// At least Microsoft Visual Studio 6 is known not to implement this test correctly.
// It emits the following code to test equality:
// fcomp qword ptr [nan]
// fnstsw ax // copie fp (floating-point) status register to ax
// test ah,40h // test bit 14 of ax (0x4000) => C3 of fp status register
// According to the following documentation on the x86 floating point status register,
// the C2 bit should be tested to test for NaN value.
// http://webster.cs.ucr.edu/AoA/Windows/HTML/RealArithmetic.html#1000117
// In Microsoft Visual Studio 2003 & 2005, the test is implemented with:
// test ah,44h // Visual Studio 2005 test both C2 & C3...
//
// To work around this, a NaN is assumed to be detected if no strict ordering is found.
inline bool floatingPointIsUnordered( double x )
{
// x != x will detect a NaN on conformant platform
// (2.0 < x && x < 1.0) will detect a NaN on non conformant platform:
// => no ordering can be found for x.
return (x != x) || (2.0 < x && x < 1.0);
}
/// \brief Tests if a floating-point is finite.
/// @return \c true if x is neither a NaN, nor +inf, nor -inf, \c false otherwise.
inline int floatingPointIsFinite( double x )
{
#if defined(CPPUNIT_HAVE_ISFINITE)
return isfinite( x );
#elif defined(CPPUNIT_HAVE_FINITE)
return finite( x );
#elif defined(CPPUNIT_HAVE__FINITE)
return _finite(x);
#else
double testInf = x * 0.0; // Produce 0.0 if x is finite, a NaN otherwise.
return testInf == 0.0 && !floatingPointIsUnordered(testInf);
#endif
}
CPPUNIT_NS_END
#endif // CPPUNIT_PORTABILITY_FLOATINGPOINT_H_INCLUDED