1 /*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
10 */
11
12 #include <sys/cdefs.h>
13 __FBSDID("$FreeBSD$");
14
15 #include <float.h>
16
17 #include "fpmath.h"
18 #include "math.h"
19 #include "math_private.h"
20
21 #define LDBL_INFNAN_EXP (LDBL_MAX_EXP * 2 - 1)
22
23 float
nexttowardf(float x,long double y)24 nexttowardf(float x, long double y)
25 {
26 union IEEEl2bits uy;
27 volatile float t;
28 int32_t hx,ix;
29
30 GET_FLOAT_WORD(hx,x);
31 ix = hx&0x7fffffff; /* |x| */
32 uy.e = y;
33
34 if((ix>0x7f800000) ||
35 (uy.bits.exp == LDBL_INFNAN_EXP &&
36 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
37 return x+y; /* x or y is nan */
38 if(x==y) return (float)y; /* x=y, return y */
39 if(ix==0) { /* x == 0 */
40 SET_FLOAT_WORD(x,(uy.bits.sign<<31)|1);/* return +-minsubnormal */
41 t = x*x;
42 if(t==x) return t; else return x; /* raise underflow flag */
43 }
44 if(hx>=0 ^ x < y) /* x -= ulp */
45 hx -= 1;
46 else /* x += ulp */
47 hx += 1;
48 ix = hx&0x7f800000;
49 if(ix>=0x7f800000) return x+x; /* overflow */
50 if(ix<0x00800000) { /* underflow */
51 t = x*x;
52 if(t!=x) { /* raise underflow flag */
53 SET_FLOAT_WORD(x,hx);
54 return x;
55 }
56 }
57 SET_FLOAT_WORD(x,hx);
58 return x;
59 }
60