55 lines
2.1 KiB
C
55 lines
2.1 KiB
C
|
#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
|