6  * Developed at SunPro, a Sun Microsystems, Inc. business.
16  *	If (assume round-to-nearest) z=x*x+y*y
24  *	(if possible, set rounding to round-to-nearest)
27  *	where x1 = x with lower 64 bits cleared, x2 = x-x1; else
29  *		t1*yy1+((x-y)*(x-y)+(t1*y2+t2*y))
30  *	where t1 = 2x with lower 64 bits cleared, t2 = 2x-t1,
31  *	yy1= y with lower 64 bits chopped, y2 = y-yy1.
37  *	hypotl(x,y) is INF if x or y is +INF or -INF; else
50 	long double a,b,t1,t2,yy1,y2,w;  in hypotl()  local
57 	if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}  in hypotl()
58 	SET_LDOUBLE_MSW64(a,ha);	/* a <- |a| */  in hypotl()
59 	SET_LDOUBLE_MSW64(b,hb);	/* b <- |b| */  in hypotl()
60 	if((ha-hb)>0x78000000000000LL) {return a+b;} /* x/y > 2**120 */  in hypotl()
62 	if(ha > 0x5f3f000000000000LL) {	/* a>2**8000 */  in hypotl()
65 	       w = a+b;			/* for sNaN */  in hypotl()
66 	       GET_LDOUBLE_LSW64(low,a);  in hypotl()
68                    w = a;  in hypotl()
70 	       if(((hb^0x7fff000000000000LL)|low)==0 && !issignalingl_inline(a))  in hypotl()
74 	   /* scale a and b by 2**-9600 */  in hypotl()
75 	   ha -= 0x2580000000000000LL;  in hypotl()
76 	   hb -= 0x2580000000000000LL;	k += 9600;  in hypotl()
77 	   SET_LDOUBLE_MSW64(a,ha);  in hypotl()
80 	if(hb < 0x20bf000000000000LL) {	/* b < 2**-8000 */  in hypotl()
84 		if((hb|low)==0) return a;  in hypotl()
88 		a *= t1;  in hypotl()
89 		k -= 16382;  in hypotl()
90 	    } else {		/* scale a and b by 2^9600 */  in hypotl()
91 		ha += 0x2580000000000000LL;	/* a *= 2^9600 */  in hypotl()
93 		k -= 9600;  in hypotl()
94 		SET_LDOUBLE_MSW64(a,ha);  in hypotl()
98     /* medium size a and b */  in hypotl()
99 	w = a-b;  in hypotl()
103 	    t2 = a-t1;  in hypotl()
104 	    w  = sqrtl(t1*t1-(b*(-b)-t2*(a+t1)));  in hypotl()
106 	    a  = a+a;  in hypotl()
109 	    y2 = b - yy1;  in hypotl()
112 	    t2 = a - t1;  in hypotl()
113 	    w  = sqrtl(t1*yy1-(w*(-w)-(t1*y2+t2*b)));  in hypotl()