1/* Rewritten for 64-bit machines by Ulrich Drepper <drepper@gmail.com>. */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, 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
13/*
14 * modf(double x, double *iptr)
15 * return fraction part of x, and return x's integral part in *iptr.
16 * Method:
17 * Bit twiddling.
18 *
19 * Exception:
20 * No exception.
21 */
22
23#include <math.h>
24#include <math_private.h>
25#include <stdint.h>
26
27static const double one = 1.0;
28
29double
30__modf(double x, double *iptr)
31{
32 int64_t i0;
33 int32_t j0;
34 EXTRACT_WORDS64(i0,x);
35 j0 = ((i0>>52)&0x7ff)-0x3ff; /* exponent of x */
36 if(j0<52) { /* integer part in x */
37 if(j0<0) { /* |x|<1 */
38 /* *iptr = +-0 */
39 INSERT_WORDS64(*iptr,i0&UINT64_C(0x8000000000000000));
40 return x;
41 } else {
42 uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
43 if((i0&i)==0) { /* x is integral */
44 *iptr = x;
45 /* return +-0 */
46 INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000));
47 return x;
48 } else {
49 INSERT_WORDS64(*iptr,i0&(~i));
50 return x - *iptr;
51 }
52 }
53 } else { /* no fraction part */
54 *iptr = x*one;
55 /* We must handle NaNs separately. */
56 if (j0 == 0x400 && (i0 & UINT64_C(0xfffffffffffff)))
57 return x*one;
58 INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000)); /* return +-0 */
59 return x;
60 }
61}
62weak_alias (__modf, modf)
63#ifdef NO_LONG_DOUBLE
64strong_alias (__modf, __modfl)
65weak_alias (__modf, modfl)
66#endif
67