ipiq: Add simple IPI latency measure sysctls (2)
[dragonfly.git] / lib / libm / src / s_modf.c
1 /* @(#)s_modf.c 5.1 93/09/24 */
2 /* $FreeBSD: head/lib/msun/src/s_modf.c 165838 2007-01-06 21:22:38Z das $ */
3 /*
4  * ====================================================
5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6  *
7  * Developed at SunPro, a Sun Microsystems, Inc. business.
8  * Permission to use, copy, modify, and distribute this
9  * software is freely granted, provided that this notice
10  * is preserved.
11  * ====================================================
12  */
13
14 /*
15  * modf(double x, double *iptr)
16  * return fraction part of x, and return x's integral part in *iptr.
17  * Method:
18  *      Bit twiddling.
19  *
20  * Exception:
21  *      No exception.
22  */
23
24 #include "math.h"
25 #include "math_private.h"
26
27 static const double one = 1.0;
28
29 double
30 modf(double x, double *iptr)
31 {
32         int32_t i0,i1,j0;
33         u_int32_t i;
34         EXTRACT_WORDS(i0,i1,x);
35         j0 = ((i0>>20)&0x7ff)-0x3ff;    /* exponent of x */
36         if(j0<20) {                     /* integer part in high x */
37             if(j0<0) {                  /* |x|<1 */
38                 INSERT_WORDS(*iptr,i0&0x80000000,0);    /* *iptr = +-0 */
39                 return x;
40             } else {
41                 i = (0x000fffff)>>j0;
42                 if(((i0&i)|i1)==0) {            /* x is integral */
43                     u_int32_t high;
44                     *iptr = x;
45                     GET_HIGH_WORD(high,x);
46                     INSERT_WORDS(x,high&0x80000000,0);  /* return +-0 */
47                     return x;
48                 } else {
49                     INSERT_WORDS(*iptr,i0&(~i),0);
50                     return x - *iptr;
51                 }
52             }
53         } else if (j0>51) {             /* no fraction part */
54             u_int32_t high;
55             if (j0 == 0x400) {          /* inf/NaN */
56                 *iptr = x;
57                 return 0.0 / x;
58             }
59             *iptr = x*one;
60             GET_HIGH_WORD(high,x);
61             INSERT_WORDS(x,high&0x80000000,0);  /* return +-0 */
62             return x;
63         } else {                        /* fraction part in low x */
64             i = ((u_int32_t)(0xffffffff))>>(j0-20);
65             if((i1&i)==0) {             /* x is integral */
66                 u_int32_t high;
67                 *iptr = x;
68                 GET_HIGH_WORD(high,x);
69                 INSERT_WORDS(x,high&0x80000000,0);      /* return +-0 */
70                 return x;
71             } else {
72                 INSERT_WORDS(*iptr,i0,i1&(~i));
73                 return x - *iptr;
74             }
75         }
76 }