1 /*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
10 *
11 * From: @(#)s_ceil.c 5.1 93/09/24
12 */
13
14 #include <sys/cdefs.h>
15 __RCSID("$NetBSD: s_ceill.c,v 1.1 2013/11/11 23:57:34 joerg Exp $");
16 #if 0
17 __FBSDID("$FreeBSD: head/lib/msun/src/s_ceill.c 176280 2008-02-14 15:10:34Z bde $");
18 #endif
19
20 /*
21 * ceill(x)
22 * Return x rounded toward -inf to integral value
23 * Method:
24 * Bit twiddling.
25 * Exception:
26 * Inexact flag raised if x not equal to ceill(x).
27 */
28 #include "namespace.h"
29
30 #include <float.h>
31 #include <math.h>
32 #include <stdint.h>
33 #include <machine/ieee.h>
34
35 #ifdef __HAVE_LONG_DOUBLE
36
37 #ifdef __weak_alias
38 __weak_alias(ceill, _ceill)
39 #endif
40
41 #ifdef LDBL_IMPLICIT_NBIT
42 #define MANH_SIZE (EXT_FRACHBITS + 1)
43 #define INC_MANH(ux, c) do { \
44 uint64_t oi = ux.extu_frach; \
45 ux.extu_frach += (c); \
46 if (ux.extu_frach < oi) \
47 ux.extu_exp++; \
48 } while (0)
49 #else
50 #define MANH_SIZE EXT_FRACHBITS
51 #define INC_MANH(ux, c) do { \
52 uint64_t oi = ux.extu_frach; \
53 ux.extu_frach += (c); \
54 if (ux.extu_frach < oi) { \
55 ux.extu_exp++; \
56 ux.extu_frach |= 1llu << (EXT_FRACHBITS - 1); \
57 } \
58 } while (0)
59 #endif
60
61 static const long double huge = 1.0e300;
62
63 long double
ceill(long double x)64 ceill(long double x)
65 {
66 union ieee_ext_u ux = { .extu_ld = x, };
67 int e = ux.extu_exp - LDBL_MAX_EXP + 1;
68
69 if (e < MANH_SIZE - 1) {
70 if (e < 0) { /* raise inexact if x != 0 */
71 if (huge + x > 0.0)
72 if (ux.extu_exp > 0 ||
73 (ux.extu_frach | ux.extu_fracl) != 0)
74 ux.extu_ld = ux.extu_sign ? -0.0 : 1.0;
75 } else {
76 uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
77 if (((ux.extu_frach & m) | ux.extu_fracl) == 0)
78 return (x); /* x is integral */
79 if (!ux.extu_sign) {
80 #ifdef LDBL_IMPLICIT_NBIT
81 if (e == 0)
82 ux.extu_exp++;
83 else
84 #endif
85 INC_MANH(ux, 1llu << (MANH_SIZE - e - 1));
86 }
87 if (huge + x > 0.0) { /* raise inexact flag */
88 ux.extu_frach &= ~m;
89 ux.extu_fracl = 0;
90 }
91 }
92 } else if (e < LDBL_MANT_DIG - 1) {
93 uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
94 if ((ux.extu_fracl & m) == 0)
95 return (x); /* x is integral */
96 if (!ux.extu_sign) {
97 if (e == MANH_SIZE - 1)
98 INC_MANH(ux, 1);
99 else {
100 uint64_t o = ux.extu_fracl;
101 ux.extu_fracl += 1llu << (LDBL_MANT_DIG - e - 1);
102 if (ux.extu_fracl < o) /* got a carry */
103 INC_MANH(ux, 1);
104 }
105 }
106 if (huge + x > 0.0) /* raise inexact flag */
107 ux.extu_fracl &= ~m;
108 }
109 return (ux.extu_ld);
110 }
111
112 #endif /* __HAVE_LONG_DOUBLE */
113