1
2 /* @(#)s_ceil.c 5.1 93/09/24 */
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 * ceil(x)
16 * Return x rounded toward -inf to integral value
17 * Method:
18 * Bit twiddling.
19 * Exception:
20 * Inexact flag raised if x not equal to ceil(x).
21 */
22
23 #include "fdlibm.h"
24
25 #ifdef _NEED_FLOAT64
26
27 __float64
ceil64(__float64 x)28 ceil64(__float64 x)
29 {
30 __int32_t i0, i1, j0, j;
31 __uint32_t i;
32 EXTRACT_WORDS(i0, i1, x);
33 j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
34 if (j0 < 20) {
35 if (j0 < 0) {
36 if (i0 < 0) {
37 i0 = 0x80000000;
38 i1 = 0;
39 } else if ((i0 | i1) != 0) {
40 i0 = 0x3ff00000;
41 i1 = 0;
42 }
43 } else {
44 i = (0x000fffff) >> j0;
45 if (((i0 & i) | i1) == 0)
46 return x; /* x is integral */
47 if (i0 > 0)
48 i0 += (0x00100000) >> j0;
49 i0 &= (~i);
50 i1 = 0;
51 }
52 } else if (j0 > 51) {
53 if (j0 == 0x400)
54 return x + x; /* inf or NaN */
55 else
56 return x; /* x is integral */
57 } else {
58 i = ((__uint32_t)(0xffffffffUL)) >> (j0 - 20);
59 if ((i1 & i) == 0)
60 return x; /* x is integral */
61 if (i0 > 0) {
62 if (j0 == 20)
63 i0 += 1;
64 else {
65 j = i1 + ((__uint32_t) 1 << (52 - j0));
66 if ((__uint32_t) j < (__uint32_t) i1)
67 i0 += 1; /* got a carry */
68 i1 = j;
69 }
70 }
71 i1 &= (~i);
72 }
73 INSERT_WORDS(x, i0, i1);
74 return x;
75 }
76
77 _MATH_ALIAS_d_d(ceil)
78
79 #endif /* _NEED_FLOAT64 */
80
