xref: /reactos/sdk/lib/crt/math/modf.c (revision 5100859e)
1 /* @(#)s_modf.c 1.3 95/01/18 */
2 /*
3  * ====================================================
4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5  *
6  * Developed at SunSoft, a Sun Microsystems, Inc. business.
7  * Permission to use, copy, modify, and distribute this
8  * software is freely granted, provided that this notice
9  * is preserved.
10  * ====================================================
11  */
12 #define modfl _dummy_modfl
13 #include <precomp.h>
14 #undef modfl
15 
16 //static const double one = 1.0;
17 
18 
19 
20 long double modfl(long double __x, long double *__i)
21 {
22 	union
23 	{
24 		long double*   __x;
25 		long_double_s*   x;
26 	} x;
27 	union
28 	{
29 		long double*    __i;
30 		long_double_s* iptr;
31 	} iptr;
32 
33 	int j0;
34 	unsigned int i;
35 
36 	x.__x = &__x;
37 	iptr.__i = __i;
38 
39 
40 	j0 = x.x->exponent - 0x3fff;  /* exponent of x */
41 
42 	if(j0<32) {                     /* integer part in high x */
43 		if(j0<0) {                  /* |x|<1 */
44 			*__i = 0.0L;
45 			iptr.iptr->sign = x.x->sign;
46 			return __x;
47 		} else {
48 
49 			i = ((unsigned int)(0xffffffff))>>(j0+1);
50 			if ( x.x->mantissal == 0 && (x.x->mantissal & i) == 0 ) {
51 				*__i =  __x;
52 				__x = 0.0L;
53 				x.x->sign = iptr.iptr->sign;
54 				return __x;
55 			}
56 			iptr.iptr->sign = x.x->sign;
57 			iptr.iptr->exponent = x.x->exponent;
58 			iptr.iptr->mantissah = x.x->mantissah&((~i));
59 			iptr.iptr->mantissal = 0;
60 
61 			return __x - *__i;
62 		}
63 	} else if (j0>63) {             /* no fraction part */
64 		*__i = __x;
65 		if (  _isnanl(__x) ||  _isinfl(__x)  )
66 			return __x;
67 
68 		__x = 0.0L;
69 		x.x->sign = iptr.iptr->sign;
70 		return __x;
71 	} else {                        /* fraction part in low x */
72 
73 		i = ((unsigned int)(0xffffffff))>>(j0-32);
74 		if ( x.x->mantissal == 0 ) {
75 			*__i =  __x;
76 			__x = 0.0L;
77 			x.x->sign = iptr.iptr->sign;
78 			return __x;
79 		}
80 		iptr.iptr->sign = x.x->sign;
81 		iptr.iptr->exponent = x.x->exponent;
82 		iptr.iptr->mantissah = x.x->mantissah;
83 		iptr.iptr->mantissal = x.x->mantissal&(~i);
84 
85 		return __x - *__i;
86 	}
87 }
88