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 int32_t i1,jj0;
30 u_int32_t i,j,se,i0,sx;
31 GET_LDOUBLE_WORDS(se,i0,i1,x);
32 sx = (se>>15)&1;
33 jj0 = (se&0x7fff)-0x3fff;
34 if(jj0<31) {
35 if(jj0<0) { /* raise inexact if x != 0 */
36 if(huge+x>0.0L) {/* return 0*sign(x) if |x|<1 */
37 if(sx) {se=0x8000;i0=0;i1=0;}
38 else if((i0|i1)!=0) { se=0x3fff;i0=0x80000000L;i1=0;}
39 }
40 } else {
41 i = (0x7fffffff)>>jj0;
42 if(((i0&i)|i1)==0) return x; /* x is integral */
43 if(huge+x>0.0L) { /* raise inexact flag */
44 if(sx==0) {
45 if (jj0>0 && (i0+(0x80000000>>jj0))>i0)
46 i0+=0x80000000>>jj0;
47 else
48 {
49 i = 0x7fffffff;
50 ++se;
51 }
52 }
53 i0 &= (~i); i1=0;
54 }
55 }
56 } else if (jj0>62) {
57 if(jj0==0x4000) return x+x; /* inf or NaN */
58 else return x; /* x is integral */
59 } else {
60 i = ((u_int32_t)(0xffffffff))>>(jj0-31);
61 if((i1&i)==0) return x; /* x is integral */
62 if(huge+x>0.0L) { /* raise inexact flag */
63 if(sx==0) {
64 if(jj0==31) i0+=1;
65 else {
66 j = i1 + (1<<(63-jj0));
67 if(j<(u_int32_t)i1) i0+=1; /* got a carry */
68 i1 = j;
69 }
70 }
71 i1 &= (~i);
72 }
73 }
74 SET_LDOUBLE_WORDS(x,se,i0,i1);
75 return x;
76 }
77
