1 /* @(#)s_nextafter.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 /* IEEE functions
14 * nextafterl(x,y)
15 * return the next machine floating-point number of x in the
16 * direction toward y.
17 * Special cases:
18 */
19
20 #include <math.h>
21
22 #include "math_private.h"
23
24 long double
nextafterl(long double x,long double y)25 nextafterl(long double x, long double y)
26 {
27 int32_t hx,hy,ix,iy;
28 u_int32_t lx,ly;
29 int32_t esx,esy;
30
31 GET_LDOUBLE_WORDS(esx,hx,lx,x);
32 GET_LDOUBLE_WORDS(esy,hy,ly,y);
33 ix = esx&0x7fff; /* |x| */
34 iy = esy&0x7fff; /* |y| */
35
36 if (((ix==0x7fff)&&(((hx&0x7fffffff)|lx)!=0)) || /* x is nan */
37 ((iy==0x7fff)&&(((hy&0x7fffffff)|ly)!=0))) /* y is nan */
38 return x+y;
39 if(x==y) return y; /* x=y, return y */
40 if((ix|hx|lx)==0) { /* x == 0 */
41 volatile long double u;
42 SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
43 u = x;
44 u = u * u; /* raise underflow flag */
45 return x;
46 }
47 if(esx>=0) { /* x > 0 */
48 if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
49 /* x > y, x -= ulp */
50 if(lx==0) {
51 if ((hx&0x7fffffff)==0) esx -= 1;
52 hx = (hx - 1) | (hx & 0x80000000);
53 }
54 lx -= 1;
55 } else { /* x < y, x += ulp */
56 lx += 1;
57 if(lx==0) {
58 hx = (hx + 1) | (hx & 0x80000000);
59 if ((hx&0x7fffffff)==0) esx += 1;
60 }
61 }
62 } else { /* x < 0 */
63 if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
64 /* x < y, x -= ulp */
65 if(lx==0) {
66 if ((hx&0x7fffffff)==0) esx -= 1;
67 hx = (hx - 1) | (hx & 0x80000000);
68 }
69 lx -= 1;
70 } else { /* x > y, x += ulp */
71 lx += 1;
72 if(lx==0) {
73 hx = (hx + 1) | (hx & 0x80000000);
74 if ((hx&0x7fffffff)==0) esx += 1;
75 }
76 }
77 }
78 esy = esx&0x7fff;
79 if(esy==0x7fff) return x+x; /* overflow */
80 if(esy==0) {
81 volatile long double u = x*x; /* underflow */
82 if(u==x) {
83 SET_LDOUBLE_WORDS(x,esx,hx,lx);
84 return x;
85 }
86 }
87 SET_LDOUBLE_WORDS(x,esx,hx,lx);
88 return x;
89 }
90 DEF_STD(nextafterl);
91 MAKE_UNUSED_CLONE(nexttowardl, nextafterl);
92