s_nextafterf.c revision 143216 
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#ifndef lint
17static char rcsid[] = "$FreeBSD: head/lib/msun/src/s_nextafterf.c 143216 2005-03-07 04:55:58Z das $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23float
24nextafterf(float x, float y)
25{
26	volatile float t;
27	int32_t hx,hy,ix,iy;
28
29	GET_FLOAT_WORD(hx,x);
30	GET_FLOAT_WORD(hy,y);
31	ix = hx&0x7fffffff;		/* |x| */
32	iy = hy&0x7fffffff;		/* |y| */
33
34	if((ix>0x7f800000) ||   /* x is nan */
35	   (iy>0x7f800000))     /* y is nan */
36	   return x+y;
37	if(x==y) return y;		/* x=y, return y */
38	if(ix==0) {				/* x == 0 */
39	    SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
40	    t = x*x;
41	    if(t==x) return t; else return x;	/* raise underflow flag */
42	}
43	if(hx>=0) {				/* x > 0 */
44	    if(hx>hy) {				/* x > y, x -= ulp */
45		hx -= 1;
46	    } else {				/* x < y, x += ulp */
47		hx += 1;
48	    }
49	} else {				/* x < 0 */
50	    if(hy>=0||hx>hy){			/* x < y, x -= ulp */
51		hx -= 1;
52	    } else {				/* x > y, x += ulp */
53		hx += 1;
54	    }
55	}
56	hy = hx&0x7f800000;
57	if(hy>=0x7f800000) return x+x;	/* overflow  */
58	if(hy<0x00800000) {		/* underflow */
59	    t = x*x;
60	    if(t!=x) {		/* raise underflow flag */
61	        SET_FLOAT_WORD(y,hx);
62		return y;
63	    }
64	}
65	SET_FLOAT_WORD(x,hx);
66	return x;
67}
68