1 | /* s_modfl.c -- long double version of s_modf.c. |
2 | */ |
3 | |
4 | /* |
5 | * ==================================================== |
6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
7 | * |
8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
9 | * Permission to use, copy, modify, and distribute this |
10 | * software is freely granted, provided that this notice |
11 | * is preserved. |
12 | * ==================================================== |
13 | */ |
14 | |
15 | #if defined(LIBM_SCCS) && !defined(lint) |
16 | static char rcsid[] = "$NetBSD: $" ; |
17 | #endif |
18 | |
19 | /* |
20 | * modfl(long double x, long double *iptr) |
21 | * return fraction part of x, and return x's integral part in *iptr. |
22 | * Method: |
23 | * Bit twiddling. |
24 | * |
25 | * Exception: |
26 | * No exception. |
27 | */ |
28 | |
29 | #include <math.h> |
30 | #include <math_private.h> |
31 | #include <math_ldbl_opt.h> |
32 | |
33 | static const long double one = 1.0; |
34 | |
35 | long double __modfl(long double x, long double *iptr) |
36 | { |
37 | int64_t i0,i1,j0; |
38 | uint64_t i; |
39 | double xhi, xlo; |
40 | |
41 | ldbl_unpack (x, &xhi, &xlo); |
42 | EXTRACT_WORDS64 (i0, xhi); |
43 | EXTRACT_WORDS64 (i1, xlo); |
44 | i1 &= 0x000fffffffffffffLL; |
45 | j0 = ((i0>>52)&0x7ff)-0x3ff; /* exponent of x */ |
46 | if(j0<52) { /* integer part in high x */ |
47 | if(j0<0) { /* |x|<1 */ |
48 | /* *iptr = +-0 */ |
49 | INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL); |
50 | *iptr = xhi; |
51 | return x; |
52 | } else { |
53 | i = (0x000fffffffffffffLL)>>j0; |
54 | if(((i0&i)|(i1&0x7fffffffffffffffLL))==0) { /* x is integral */ |
55 | *iptr = x; |
56 | /* return +-0 */ |
57 | INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL); |
58 | x = xhi; |
59 | return x; |
60 | } else { |
61 | INSERT_WORDS64 (xhi, i0&(~i)); |
62 | *iptr = xhi; |
63 | return x - *iptr; |
64 | } |
65 | } |
66 | } else if (j0>103) { /* no fraction part */ |
67 | *iptr = x*one; |
68 | /* We must handle NaNs separately. */ |
69 | if ((i0 & 0x7fffffffffffffffLL) > 0x7ff0000000000000LL) |
70 | return x*one; |
71 | /* return +-0 */ |
72 | INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL); |
73 | x = xhi; |
74 | return x; |
75 | } else { /* fraction part in low x */ |
76 | i = -1ULL>>(j0-52); |
77 | if((i1&i)==0) { /* x is integral */ |
78 | *iptr = x; |
79 | /* return +-0 */ |
80 | INSERT_WORDS64 (xhi, i0&0x8000000000000000ULL); |
81 | x = xhi; |
82 | return x; |
83 | } else { |
84 | INSERT_WORDS64 (xhi, i0); |
85 | INSERT_WORDS64 (xlo, i1&(~i)); |
86 | *iptr = ldbl_pack (xhi, xlo); |
87 | return x - *iptr; |
88 | } |
89 | } |
90 | } |
91 | #if IS_IN (libm) |
92 | long_double_symbol (libm, __modfl, modfl); |
93 | #else |
94 | long_double_symbol (libc, __modfl, modfl); |
95 | #endif |
96 | |