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 #include <math.h>
23
24 #include "math_private.h"
25
26 static const long double huge = 1.0e4930L;
27
28 long double
floorl(long double x)29 floorl(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) {
38 if(i0>=0)
39 return 0.0L;
40 else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
41 return -1.0L;
42 }
43 } else {
44 i = (0x0000ffffffffffffULL)>>jj0;
45 if(((i0&i)|i1)==0) return x; /* x is integral */
46 if(huge+x>0.0) { /* raise inexact flag */
47 if(i0<0) i0 += (0x0001000000000000LL)>>jj0;
48 i0 &= (~i); i1=0;
49 }
50 }
51 } else if (jj0>111) {
52 if(jj0==0x4000) return x+x; /* inf or NaN */
53 else return x; /* x is integral */
54 } else {
55 i = -1ULL>>(jj0-48);
56 if((i1&i)==0) return x; /* x is integral */
57 if(huge+x>0.0) { /* raise inexact flag */
58 if(i0<0) {
59 if(jj0==48) i0+=1;
60 else {
61 j = i1+(1LL<<(112-jj0));
62 if(j<i1) i0 +=1 ; /* got a carry */
63 i1=j;
64 }
65 }
66 i1 &= (~i);
67 }
68 }
69 SET_LDOUBLE_WORDS64(x,i0,i1);
70 return x;
71 }
72 DEF_STD(floorl);
73