e_hypotf.c revision 97409 
1/* e_hypotf.c -- float version of e_hypot.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/e_hypotf.c 97409 2002-05-28 17:51:46Z alfred $";
18#endif
19
20#include "math.h"
21#include "math_private.h"
22
23	float __ieee754_hypotf(float x, float y)
24{
25	float a=x,b=y,t1,t2,y1,y2,w;
26	int32_t j,k,ha,hb;
27
28	GET_FLOAT_WORD(ha,x);
29	ha &= 0x7fffffff;
30	GET_FLOAT_WORD(hb,y);
31	hb &= 0x7fffffff;
32	if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
33	SET_FLOAT_WORD(a,ha);	/* a <- |a| */
34	SET_FLOAT_WORD(b,hb);	/* b <- |b| */
35	if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */
36	k=0;
37	if(ha > 0x58800000) {	/* a>2**50 */
38	   if(ha >= 0x7f800000) {	/* Inf or NaN */
39	       w = a+b;			/* for sNaN */
40	       if(ha == 0x7f800000) w = a;
41	       if(hb == 0x7f800000) w = b;
42	       return w;
43	   }
44	   /* scale a and b by 2**-68 */
45	   ha -= 0x22000000; hb -= 0x22000000;	k += 68;
46	   SET_FLOAT_WORD(a,ha);
47	   SET_FLOAT_WORD(b,hb);
48	}
49	if(hb < 0x26800000) {	/* b < 2**-50 */
50	    if(hb <= 0x007fffff) {	/* subnormal b or 0 */
51	        if(hb==0) return a;
52		SET_FLOAT_WORD(t1,0x7e800000);	/* t1=2^126 */
53		b *= t1;
54		a *= t1;
55		k -= 126;
56	    } else {		/* scale a and b by 2^68 */
57	        ha += 0x22000000; 	/* a *= 2^68 */
58		hb += 0x22000000;	/* b *= 2^68 */
59		k -= 68;
60		SET_FLOAT_WORD(a,ha);
61		SET_FLOAT_WORD(b,hb);
62	    }
63	}
64    /* medium size a and b */
65	w = a-b;
66	if (w>b) {
67	    SET_FLOAT_WORD(t1,ha&0xfffff000);
68	    t2 = a-t1;
69	    w  = __ieee754_sqrtf(t1*t1-(b*(-b)-t2*(a+t1)));
70	} else {
71	    a  = a+a;
72	    SET_FLOAT_WORD(y1,hb&0xfffff000);
73	    y2 = b - y1;
74	    SET_FLOAT_WORD(t1,ha+0x00800000);
75	    t2 = a - t1;
76	    w  = __ieee754_sqrtf(t1*y1-(w*(-w)-(t1*y2+t2*b)));
77	}
78	if(k!=0) {
79	    SET_FLOAT_WORD(t1,0x3f800000+(k<<23));
80	    return t1*w;
81	} else return w;
82}
83