1/* s_nexttowardf.c -- float version of s_nextafter.c.
2 */
3
4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 */
14
15#if defined(LIBM_SCCS) && !defined(lint)
16static char rcsid[] = "$NetBSD: $";
17#endif
18
19#include <errno.h>
20#include <math.h>
21#include <math-barriers.h>
22#include <math_private.h>
23#include <float.h>
24
25float __nexttowardf(float x, long double y)
26{
27 int32_t hx,ix,iy;
28 uint32_t hy,ly,esy;
29
30 GET_FLOAT_WORD(hx,x);
31 GET_LDOUBLE_WORDS(esy,hy,ly,y);
32 ix = hx&0x7fffffff; /* |x| */
33 iy = esy&0x7fff; /* |y| */
34
35 if((ix>0x7f800000) || /* x is nan */
36 (iy>=0x7fff&&((hy|ly)!=0))) /* y is nan */
37 return x+y;
38 if((long double) x==y) return y; /* x=y, return y */
39 if(ix==0) { /* x == 0 */
40 float u;
41 SET_FLOAT_WORD(x,((esy&0x8000)<<16)|1);/* return +-minsub*/
42 u = math_opt_barrier (x);
43 u = u * u;
44 math_force_eval (u); /* raise underflow flag */
45 return x;
46 }
47 if(hx>=0) { /* x > 0 */
48 if(x > y) { /* x -= ulp */
49 hx -= 1;
50 } else { /* x < y, x += ulp */
51 hx += 1;
52 }
53 } else { /* x < 0 */
54 if(x < y) { /* x -= ulp */
55 hx -= 1;
56 } else { /* x > y, x += ulp */
57 hx += 1;
58 }
59 }
60 hy = hx&0x7f800000;
61 if(hy>=0x7f800000) {
62 float u = x+x; /* overflow */
63 math_force_eval (u);
64 __set_errno (ERANGE);
65 }
66 if(hy<0x00800000) {
67 float u = x*x; /* underflow */
68 math_force_eval (u); /* raise underflow flag */
69 __set_errno (ERANGE);
70 }
71 SET_FLOAT_WORD(x,hx);
72 return x;
73}
74weak_alias (__nexttowardf, nexttowardf)
75

source code of glibc/sysdeps/ieee754/ldbl-96/s_nexttowardf.c