1 | /* s_nexttowardf.c -- float version of s_nextafter.c. |
2 | * Special i387 version. |
3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
4 | */ |
5 | |
6 | /* |
7 | * ==================================================== |
8 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
9 | * |
10 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
11 | * Permission to use, copy, modify, and distribute this |
12 | * software is freely granted, provided that this notice |
13 | * is preserved. |
14 | * ==================================================== |
15 | */ |
16 | |
17 | #if defined(LIBM_SCCS) && !defined(lint) |
18 | static char rcsid[] = "$NetBSD: $" ; |
19 | #endif |
20 | |
21 | #include <errno.h> |
22 | #include <math.h> |
23 | #include <math-barriers.h> |
24 | #include <math_private.h> |
25 | #include <float.h> |
26 | |
27 | float __nexttowardf(float x, long double y) |
28 | { |
29 | int32_t hx,ix,iy; |
30 | uint32_t hy,ly,esy; |
31 | |
32 | GET_FLOAT_WORD(hx,x); |
33 | GET_LDOUBLE_WORDS(esy,hy,ly,y); |
34 | ix = hx&0x7fffffff; /* |x| */ |
35 | iy = esy&0x7fff; /* |y| */ |
36 | |
37 | /* Intel's extended format has the normally implicit 1 explicit |
38 | present. Sigh! */ |
39 | if((ix>0x7f800000) || /* x is nan */ |
40 | (iy>=0x7fff&&(((hy&0x7fffffff)|ly)!=0))) /* y is nan */ |
41 | return x+y; |
42 | if((long double) x==y) return y; /* x=y, return y */ |
43 | if(ix==0) { /* x == 0 */ |
44 | float u; |
45 | SET_FLOAT_WORD(x,((esy&0x8000)<<16)|1);/* return +-minsub*/ |
46 | u = math_opt_barrier (x); |
47 | u = u * u; |
48 | math_force_eval (u); /* raise underflow flag */ |
49 | return x; |
50 | } |
51 | if(hx>=0) { /* x > 0 */ |
52 | if(x > y) { /* x -= ulp */ |
53 | hx -= 1; |
54 | } else { /* x < y, x += ulp */ |
55 | hx += 1; |
56 | } |
57 | } else { /* x < 0 */ |
58 | if(x < y) { /* x -= ulp */ |
59 | hx -= 1; |
60 | } else { /* x > y, x += ulp */ |
61 | hx += 1; |
62 | } |
63 | } |
64 | hy = hx&0x7f800000; |
65 | if(hy>=0x7f800000) { |
66 | float u = x+x; /* overflow */ |
67 | math_force_eval (u); |
68 | __set_errno (ERANGE); |
69 | } |
70 | if(hy<0x00800000) { |
71 | float u = x*x; /* underflow */ |
72 | math_force_eval (u); /* raise underflow flag */ |
73 | __set_errno (ERANGE); |
74 | } |
75 | SET_FLOAT_WORD(x,hx); |
76 | return x; |
77 | } |
78 | weak_alias (__nexttowardf, nexttowardf) |
79 | |