reactos/sdk/lib/crt/float/fpclass.c

59 lines
1.3 KiB
C

/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS system libraries
* FILE: lib/sdk/crt/float/fpclass.c
* PURPOSE: Floating-point classes
* PROGRAMER: Pierre Schweitzer (pierre@reactos.org)
* REFERENCE: http://babbage.cs.qc.cuny.edu/IEEE-754/References.xhtml
*/
#include <precomp.h>
#include <float.h>
#include <internal/ieee.h>
/*
* @implemented
*/
int _fpclass(double __d)
{
union
{
double* __d;
double_s* d;
} d;
d.__d = &__d;
/* With 0x7ff, it can only be infinity or NaN */
if (d.d->exponent == 0x7ff)
{
if (d.d->mantissah == 0 && d.d->mantissal == 0)
{
return (d.d->sign == 0) ? _FPCLASS_PINF : _FPCLASS_NINF;
}
/* Windows will never return Signaling NaN */
else
{
return _FPCLASS_QNAN;
}
}
/* With 0, it can only be zero or denormalized number */
if (d.d->exponent == 0)
{
if (d.d->mantissah == 0 && d.d->mantissal == 0)
{
return (d.d->sign == 0) ? _FPCLASS_PZ : _FPCLASS_NZ;
}
else
{
return (d.d->sign == 0) ? _FPCLASS_PD : _FPCLASS_ND;
}
}
/* Only remain normalized numbers */
else
{
return (d.d->sign == 0) ? _FPCLASS_PN : _FPCLASS_NN;
}
}