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/* IEEE functions
27 * nextafter(x,y)
28 * return the next machine floating-point number of x in the
29 * direction toward y.
30 * Special cases:
31 */
32
33#include "fdlibm.h"
34
35#ifdef __STDC__
36 double nextafter(double x, double y)
37#else
38 double nextafter(x,y)
39 double x,y;
40#endif
41{
42 int hx,hy,ix,iy;
43 unsigned lx,ly;
44
45 hx = __HI(x); /* high word of x */
46 lx = __LO(x); /* low word of x */
47 hy = __HI(y); /* high word of y */
48 ly = __LO(y); /* low word of y */
49 ix = hx&0x7fffffff; /* |x| */
50 iy = hy&0x7fffffff; /* |y| */
51
52 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
53 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
54 return x+y;
55 if(x==y) return x; /* x=y, return x */
56 if((ix|lx)==0) { /* x == 0 */
57 __HI(x) = hy&0x80000000; /* return +-minsubnormal */
58 __LO(x) = 1;
59 y = x*x;
60 if(y==x) return y; else return x; /* raise underflow flag */
61 }
62 if(hx>=0) { /* x > 0 */
63 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
64 if(lx==0) hx -= 1;
65 lx -= 1;
66 } else { /* x < y, x += ulp */
67 lx += 1;
68 if(lx==0) hx += 1;
69 }
70 } else { /* x < 0 */
71 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
72 if(lx==0) hx -= 1;
73 lx -= 1;
74 } else { /* x > y, x += ulp */
75 lx += 1;
76 if(lx==0) hx += 1;
77 }
78 }
79 hy = hx&0x7ff00000;
80 if(hy>=0x7ff00000) return x+x; /* overflow */
81 if(hy<0x00100000) { /* underflow */
82 y = x*x;
83 if(y!=x) { /* raise underflow flag */
84 __HI(y) = hx; __LO(y) = lx;
85 return y;
86 }
87 }
88 __HI(x) = hx; __LO(x) = lx;
89 return x;
90}
91