1 /* @(#)s_floor.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 * floorl(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 floor(x).
20 */
21
22
23
24 static const long double huge = 1.0e4930L;
25
26 long double
floorl(long double x)27 floorl(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) {
36 if(i0>=0)
37 return 0.0L;
38 else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
39 return -1.0L;
40 }
41 } else {
42 i = (0x0000ffffffffffffULL)>>jj0;
43 if(((i0&i)|i1)==0) return x; /* x is integral */
44 if(huge+x>0.0L) { /* 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>0.0L) { /* raise inexact flag */
56 if(i0<0) {
57 if(jj0==48) i0+=1;
58 else {
59 j = i1+(1LL<<(112-jj0));
60 if(j<(u_int64_t)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
