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 int32_t i1,jj0;
32 u_int32_t i,j,se,i0,sx;
33 GET_LDOUBLE_WORDS(se,i0,i1,x);
34 sx = (se>>15)&1;
35 jj0 = (se&0x7fff)-0x3fff;
36 if(jj0<31) {
37 if(jj0<0) { /* raise inexact if x != 0 */
38 if(huge+x>0.0) {
39 if(sx==0)
40 return 0.0L;
41 else if(((se&0x7fff)|i0|i1)!=0)
42 return -1.0L;
43 }
44 } else {
45 i = (0x7fffffff)>>jj0;
46 if(((i0&i)|i1)==0) return x; /* x is integral */
47 if(huge+x>0.0) { /* raise inexact flag */
48 if(sx) {
49 if (jj0>0 && (i0+(0x80000000>>jj0))>i0)
50 i0 += (0x80000000)>>jj0;
51 else
52 {
53 i = 0x7fffffff;
54 ++se;
55 }
56 }
57 i0 &= (~i); i1=0;
58 }
59 }
60 } else if (jj0>62) {
61 if(jj0==0x4000) return x+x; /* inf or NaN */
62 else return x; /* x is integral */
63 } else {
64 i = ((u_int32_t)(0xffffffff))>>(jj0-31);
65 if((i1&i)==0) return x; /* x is integral */
66 if(huge+x>0.0) { /* raise inexact flag */
67 if(sx) {
68 if(jj0==31) i0+=1;
69 else {
70 j = i1+(1<<(63-jj0));
71 if(j<(u_int32_t)i1) i0 +=1 ; /* got a carry */
72 i1=j;
73 }
74 }
75 i1 &= (~i);
76 }
77 }
78 SET_LDOUBLE_WORDS(x,se,i0,i1);
79 return x;
80 }
81