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 * ceill(x)
15 * Return x rounded toward -inf to integral value
16 * Method:
17 * Bit twiddling.
18 * Exception:
19 * Inexact flag raised if x not equal to ceil(x).
20 */
21
22 #include <math.h>
23
24 #include "math_private.h"
25
26 static const long double huge = 1.0e4930L;
27
28 long double
ceill(long double x)29 ceill(long double x)
30 {
31 int64_t i0,i1,jj0;
32 u_int64_t i,j;
33 GET_LDOUBLE_WORDS64(i0,i1,x);
34 jj0 = ((i0>>48)&0x7fff)-0x3fff;
35 if(jj0<48) {
36 if(jj0<0) { /* raise inexact if x != 0 */
37 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
38 if(i0<0) {i0=0x8000000000000000ULL;i1=0;}
39 else if((i0|i1)!=0) { i0=0x3fff000000000000ULL;i1=0;}
40 }
41 } else {
42 i = (0x0000ffffffffffffULL)>>jj0;
43 if(((i0&i)|i1)==0) return x; /* x is integral */
44 if(huge+x>0.0) { /* raise inexact flag */
45 if(i0>0) i0 += (0x0001000000000000LL)>>jj0;
46 i0 &= (~i); i1=0;
47 }
48 }
49 } else if (jj0>111) {
50 if(jj0==0x4000) return x+x; /* inf or NaN */
51 else return x; /* x is integral */
52 } else {
53 i = -1ULL>>(jj0-48);
54 if((i1&i)==0) return x; /* x is integral */
55 if(huge+x>0.0) { /* raise inexact flag */
56 if(i0>0) {
57 if(jj0==48) i0+=1;
58 else {
59 j = i1+(1LL<<(112-jj0));
60 if(j<i1) i0 +=1 ; /* got a carry */
61 i1=j;
62 }
63 }
64 i1 &= (~i);
65 }
66 }
67 SET_LDOUBLE_WORDS64(x,i0,i1);
68 return x;
69 }
70