1/*
2 * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26/*
27 * floor(x)
28 * Return x rounded toward -inf to integral value
29 * Method:
30 * Bit twiddling.
31 * Exception:
32 * Inexact flag raised if x not equal to floor(x).
33 */
34
35#include "fdlibm.h"
36
37#ifdef __STDC__
38static const double huge = 1.0e300;
39#else
40static double huge = 1.0e300;
41#endif
42
43#ifdef __STDC__
44 double floor(double x)
45#else
46 double floor(x)
47 double x;
48#endif
49{
50 int i0,i1,j0;
51 unsigned i,j;
52 i0 = __HI(x);
53 i1 = __LO(x);
54 j0 = ((i0>>20)&0x7ff)-0x3ff;
55 if(j0<20) {
56 if(j0<0) { /* raise inexact if x != 0 */
57 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
58 if(i0>=0) {i0=i1=0;}
59 else if(((i0&0x7fffffff)|i1)!=0)
60 { i0=0xbff00000;i1=0;}
61 }
62 } else {
63 i = (0x000fffff)>>j0;
64 if(((i0&i)|i1)==0) return x; /* x is integral */
65 if(huge+x>0.0) { /* raise inexact flag */
66 if(i0<0) i0 += (0x00100000)>>j0;
67 i0 &= (~i); i1=0;
68 }
69 }
70 } else if (j0>51) {
71 if(j0==0x400) return x+x; /* inf or NaN */
72 else return x; /* x is integral */
73 } else {
74 i = ((unsigned)(0xffffffff))>>(j0-20);
75 if((i1&i)==0) return x; /* x is integral */
76 if(huge+x>0.0) { /* raise inexact flag */
77 if(i0<0) {
78 if(j0==20) i0+=1;
79 else {
80 j = i1+(1<<(52-j0));
81 if(j<i1) i0 +=1 ; /* got a carry */
82 i1=j;
83 }
84 }
85 i1 &= (~i);
86 }
87 }
88 __HI(x) = i0;
89 __LO(x) = i1;
90 return x;
91}
92