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 int64_t hx,hy,ix,iy;
28 u_int64_t lx,ly;
29
30 GET_LDOUBLE_WORDS64(hx,lx,x);
31 GET_LDOUBLE_WORDS64(hy,ly,y);
32 ix = hx&0x7fffffffffffffffLL; /* |x| */
33 iy = hy&0x7fffffffffffffffLL; /* |y| */
34
35 if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) || /* x is nan */
36 ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0)) /* y is nan */
37 return x+y;
38 if(x==y) return y; /* x=y, return y */
39 if((ix|lx)==0) { /* x == 0 */
40 volatile long double u;
41 SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
42 u = x;
43 u = u * u; /* raise underflow flag */
44 return x;
45 }
46 if(hx>=0) { /* x > 0 */
47 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
48 if(lx==0) hx--;
49 lx--;
50 } else { /* x < y, x += ulp */
51 lx++;
52 if(lx==0) hx++;
53 }
54 } else { /* x < 0 */
55 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
56 if(lx==0) hx--;
57 lx--;
58 } else { /* x > y, x += ulp */
59 lx++;
60 if(lx==0) hx++;
61 }
62 }
63 hy = hx&0x7fff000000000000LL;
64 if(hy==0x7fff000000000000LL) return x+x;/* overflow */
65 if(hy==0) {
66 volatile long double u = x*x; /* underflow */
67 }
68 SET_LDOUBLE_WORDS64(x,hx,lx);
69 return x;
70 }
71 DEF_STD(nextafterl);
72 MAKE_UNUSED_CLONE(nexttowardl, nextafterl);
73