s_nextafterf.c revision 2117 
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[] = "$Id: s_nextafterf.c,v 1.2 1994/08/18 23:07:15 jtc Exp $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23#ifdef __STDC__
24	float nextafterf(float x, float y)
25#else
26	float nextafterf(x,y)
27	float x,y;
28#endif
29{
30	int32_t hx,hy,ix,iy;
31
32	GET_FLOAT_WORD(hx,x);
33	GET_FLOAT_WORD(hy,y);
34	ix = hx&0x7fffffff;		/* |x| */
35	iy = hy&0x7fffffff;		/* |y| */
36
37	if((ix>0x7f800000) ||   /* x is nan */
38	   (iy>0x7f800000))     /* y is nan */
39	   return x+y;
40	if(x==y) return x;		/* x=y, return x */
41	if(ix==0) {				/* x == 0 */
42	    SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
43	    y = x*x;
44	    if(y==x) return y; else return x;	/* raise underflow flag */
45	}
46	if(hx>=0) {				/* x > 0 */
47	    if(hx>hy) {				/* x > y, x -= ulp */
48		hx -= 1;
49	    } else {				/* x < y, x += ulp */
50		hx += 1;
51	    }
52	} else {				/* x < 0 */
53	    if(hy>=0||hx>hy){			/* x < y, x -= ulp */
54		hx -= 1;
55	    } else {				/* x > y, x += ulp */
56		hx += 1;
57	    }
58	}
59	hy = hx&0x7f800000;
60	if(hy>=0x7f800000) return x+x;	/* overflow  */
61	if(hy<0x00800000) {		/* underflow */
62	    y = x*x;
63	    if(y!=x) {		/* raise underflow flag */
64	        SET_FLOAT_WORD(y,hx);
65		return y;
66	    }
67	}
68	SET_FLOAT_WORD(x,hx);
69	return x;
70}
71