1 | /* @(#)s_ceil.c 5.1 93/09/24 */ |
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 | * ceil(x) |
15 | * Return x rounded toward -inf to integral value |
16 | * Method: |
17 | * Bit twiddling. |
18 | */ |
19 | |
20 | #define NO_MATH_REDIRECT |
21 | #include <math.h> |
22 | #include <math_private.h> |
23 | #include <libm-alias-double.h> |
24 | #include <math-use-builtins.h> |
25 | |
26 | double |
27 | __ceil (double x) |
28 | { |
29 | #if USE_CEIL_BUILTIN |
30 | return __builtin_ceil (x); |
31 | #else |
32 | /* Use generic implementation. */ |
33 | int64_t i0, i; |
34 | int32_t j0; |
35 | EXTRACT_WORDS64 (i0, x); |
36 | j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; |
37 | if (j0 <= 51) |
38 | { |
39 | if (j0 < 0) |
40 | { |
41 | /* return 0 * sign(x) if |x| < 1 */ |
42 | if (i0 < 0) |
43 | i0 = INT64_C (0x8000000000000000); |
44 | else if (i0 != 0) |
45 | i0 = INT64_C (0x3ff0000000000000); |
46 | } |
47 | else |
48 | { |
49 | i = INT64_C (0x000fffffffffffff) >> j0; |
50 | if ((i0 & i) == 0) |
51 | return x; /* x is integral */ |
52 | if (i0 > 0) |
53 | i0 += UINT64_C (0x0010000000000000) >> j0; |
54 | i0 &= ~i; |
55 | } |
56 | } |
57 | else |
58 | { |
59 | if (j0 == 0x400) |
60 | return x + x; /* inf or NaN */ |
61 | else |
62 | return x; /* x is integral */ |
63 | } |
64 | INSERT_WORDS64 (x, i0); |
65 | return x; |
66 | #endif /* ! USE_CEIL_BUILTIN */ |
67 | } |
68 | #ifndef __ceil |
69 | libm_alias_double (__ceil, ceil) |
70 | #endif |
71 | |