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 #ifndef lint
13 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nexttowardf.c,v 1.1 2005/03/07 04:57:38 das Exp $";
14 #endif
15
16 #include <float.h>
17
18 #include "fpmath.h"
19 #include "math.h"
20 #include "math_private.h"
21
22 #define LDBL_INFNAN_EXP (LDBL_MAX_EXP * 2 - 1)
23
24 float
nexttowardf(float x,long double y)25 nexttowardf(float x, long double y)
26 {
27 union IEEEl2bits uy;
28 volatile float t;
29 int32_t hx,ix;
30
31 GET_FLOAT_WORD(hx,x);
32 ix = hx&0x7fffffff; /* |x| */
33 uy.e = y;
34
35 if((ix>0x7f800000) ||
36 (uy.bits.exp == LDBL_INFNAN_EXP &&
37 ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
38 return x+y; /* x or y is nan */
39 if(x==y) return (float)y; /* x=y, return y */
40 if(ix==0) { /* x == 0 */
41 SET_FLOAT_WORD(x,(uy.bits.sign<<31)|1);/* return +-minsubnormal */
42 t = x*x;
43 if(t==x) return t; else return x; /* raise underflow flag */
44 }
45 if(hx>=0 ^ x < y) /* x -= ulp */
46 hx -= 1;
47 else /* x += ulp */
48 hx += 1;
49 ix = hx&0x7f800000;
50 if(ix>=0x7f800000) return x+x; /* overflow */
51 if(ix<0x00800000) { /* underflow */
52 t = x*x;
53 if(t!=x) { /* raise underflow flag */
54 SET_FLOAT_WORD(y,hx);
55 return y;
56 }
57 }
58 SET_FLOAT_WORD(x,hx);
59 return x;
60 }
61