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 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) {
37 if(sx==0)
38 return 0.0L;
39 else if(((se&0x7fff)|i0|i1)!=0)
40 return -1.0L;
41 }
42 } else {
43 i = (0x7fffffff)>>jj0;
44 if(((i0&i)|i1)==0) return x; /* x is integral */
45 if(huge+x>0.0L) { /* raise inexact flag */
46 if(sx) {
47 if (jj0>0 && (i0+(0x80000000>>jj0))>i0)
48 i0 += (0x80000000)>>jj0;
49 else
50 {
51 i = 0x7fffffff;
52 ++se;
53 }
54 }
55 i0 &= (~i); i1=0;
56 }
57 }
58 } else if (jj0>62) {
59 if(jj0==0x4000) return x+x; /* inf or NaN */
60 else return x; /* x is integral */
61 } else {
62 i = ((u_int32_t)(0xffffffff))>>(jj0-31);
63 if((i1&i)==0) return x; /* x is integral */
64 if(huge+x>0.0L) { /* raise inexact flag */
65 if(sx) {
66 if(jj0==31) i0+=1;
67 else {
68 j = i1+(1<<(63-jj0));
69 if(j<(u_int32_t)i1) i0 +=1 ; /* got a carry */
70 i1=j;
71 }
72 }
73 i1 &= (~i);
74 }
75 }
76 SET_LDOUBLE_WORDS(x,se,i0,i1);
77 return x;
78 }
79
