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
23
24 static const long double huge = 1.0e4930L;
25
26 long double
ceill(long double x)27 ceill(long double x)
28 {
29 int64_t i0,i1,jj0;
30 u_int64_t i,j;
31 GET_LDOUBLE_WORDS64(i0,i1,x);
32 jj0 = ((i0>>48)&0x7fff)-0x3fff;
33 if(jj0<48) {
34 if(jj0<0) { /* raise inexact if x != 0 */
35 if(huge+x>0.0L) {/* return 0*sign(x) if |x|<1 */
36 if(i0<0) {i0=0x8000000000000000ULL;i1=0;}
37 else if((i0|i1)!=0) { i0=0x3fff000000000000ULL;i1=0;}
38 }
39 } else {
40 i = (0x0000ffffffffffffULL)>>jj0;
41 if(((i0&i)|i1)==0) return x; /* x is integral */
42 if(huge+x>0.0L) { /* raise inexact flag */
43 if(i0>0) i0 += (0x0001000000000000LL)>>jj0;
44 i0 &= (~i); i1=0;
45 }
46 }
47 } else if (jj0>111) {
48 if(jj0==0x4000) return x+x; /* inf or NaN */
49 else return x; /* x is integral */
50 } else {
51 i = -1ULL>>(jj0-48);
52 if((i1&i)==0) return x; /* x is integral */
53 if(huge+x>0.0L) { /* raise inexact flag */
54 if(i0>0) {
55 if(jj0==48) i0+=1;
56 else {
57 j = i1+(1LL<<(112-jj0));
58 if(j<(u_int64_t)i1) i0 +=1 ; /* got a carry */
59 i1=j;
60 }
61 }
62 i1 &= (~i);
63 }
64 }
65 SET_LDOUBLE_WORDS64(x,i0,i1);
66 return x;
67 }
68
