s_nextafterf.c revision 176451 
1/* s_nextafterf.c -- float version of s_nextafter.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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#include <sys/cdefs.h>
17__FBSDID("$FreeBSD: head/lib/msun/src/s_nextafterf.c 176451 2008-02-22 02:30:36Z das $");
18
19#include "math.h"
20#include "math_private.h"
21
22float
23nextafterf(float x, float y)
24{
25	volatile float t;
26	int32_t hx,hy,ix,iy;
27
28	GET_FLOAT_WORD(hx,x);
29	GET_FLOAT_WORD(hy,y);
30	ix = hx&0x7fffffff;		/* |x| */
31	iy = hy&0x7fffffff;		/* |y| */
32
33	if((ix>0x7f800000) ||   /* x is nan */
34	   (iy>0x7f800000))     /* y is nan */
35	   return x+y;
36	if(x==y) return y;		/* x=y, return y */
37	if(ix==0) {				/* x == 0 */
38	    SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
39	    t = x*x;
40	    if(t==x) return t; else return x;	/* raise underflow flag */
41	}
42	if(hx>=0) {				/* x > 0 */
43	    if(hx>hy) {				/* x > y, x -= ulp */
44		hx -= 1;
45	    } else {				/* x < y, x += ulp */
46		hx += 1;
47	    }
48	} else {				/* x < 0 */
49	    if(hy>=0||hx>hy){			/* x < y, x -= ulp */
50		hx -= 1;
51	    } else {				/* x > y, x += ulp */
52		hx += 1;
53	    }
54	}
55	hy = hx&0x7f800000;
56	if(hy>=0x7f800000) return x+x;	/* overflow  */
57	if(hy<0x00800000) {		/* underflow */
58	    t = x*x;
59	    if(t!=x) {		/* raise underflow flag */
60	        SET_FLOAT_WORD(y,hx);
61		return y;
62	    }
63	}
64	SET_FLOAT_WORD(x,hx);
65	return x;
66}
67