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Reactos
1/*
2 * COPYRIGHT: See COPYING in the top level directory
3 * PROJECT: ReactOS system libraries
4 * FILE: lib/sdk/crt/float/fpclass.c
5 * PURPOSE: Floating-point classes
6 * PROGRAMER: Pierre Schweitzer (pierre@reactos.org)
7 * REFERENCE: http://babbage.cs.qc.cuny.edu/IEEE-754/References.xhtml
8 */
9
10#include <precomp.h>
11#include <float.h>
12#include <internal/ieee.h>
13
14/*
15 * @implemented
16 */
17int _fpclass(double __d)
18{
19 union
20 {
21 double* __d;
22 double_s* d;
23 } d;
24 d.__d = &__d;
25
26
27 /* With 0x7ff, it can only be infinity or NaN */
28 if (d.d->exponent == 0x7ff)
29 {
30 if (d.d->mantissah == 0 && d.d->mantissal == 0)
31 {
32 return (d.d->sign == 0) ? _FPCLASS_PINF : _FPCLASS_NINF;
33 }
34 /* Windows will never return Signaling NaN */
35 else
36 {
37 return _FPCLASS_QNAN;
38 }
39 }
40
41 /* With 0, it can only be zero or denormalized number */
42 if (d.d->exponent == 0)
43 {
44 if (d.d->mantissah == 0 && d.d->mantissal == 0)
45 {
46 return (d.d->sign == 0) ? _FPCLASS_PZ : _FPCLASS_NZ;
47 }
48 else
49 {
50 return (d.d->sign == 0) ? _FPCLASS_PD : _FPCLASS_ND;
51 }
52 }
53 /* Only remain normalized numbers */
54 else
55 {
56 return (d.d->sign == 0) ? _FPCLASS_PN : _FPCLASS_NN;
57 }
58}