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 | #include <math.h> |
21 | #include <math_private.h> |
22 | #include <libm-alias-double.h> |
23 | |
24 | double |
25 | __ceil(double x) |
26 | { |
27 | int64_t i0,i; |
28 | int32_t j0; |
29 | EXTRACT_WORDS64(i0,x); |
30 | j0 = ((i0>>52)&0x7ff)-0x3ff; |
31 | if(j0<=51) { |
32 | if(j0<0) { |
33 | /* return 0*sign(x) if |x|<1 */ |
34 | if(i0<0) {i0=INT64_C(0x8000000000000000);} |
35 | else if(i0!=0) { i0=INT64_C(0x3ff0000000000000);} |
36 | } else { |
37 | i = INT64_C(0x000fffffffffffff)>>j0; |
38 | if((i0&i)==0) return x; /* x is integral */ |
39 | if(i0>0) i0 += UINT64_C(0x0010000000000000)>>j0; |
40 | i0 &= (~i); |
41 | } |
42 | } else { |
43 | if(j0==0x400) return x+x; /* inf or NaN */ |
44 | else return x; /* x is integral */ |
45 | } |
46 | INSERT_WORDS64(x,i0); |
47 | return x; |
48 | } |
49 | #ifndef __ceil |
50 | libm_alias_double (__ceil, ceil) |
51 | #endif |
52 | |