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