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      1 /* e_hypotf.c -- float version of e_hypot.c.
      2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) 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 #if defined(LIBM_SCCS) && !defined(lint)
     18 __RCSID("$NetBSD: e_hypotf.c,v 1.10 2016/01/24 20:34:30 gson Exp $");
     19 #endif
     20 
     21 #include "math.h"
     22 #include "math_private.h"
     23 
     24 float
     25 __ieee754_hypotf(float x, float y)
     26 {
     27 	float a=x,b=y,t1,t2,yy1,y2,w;
     28 	int32_t j,k,ha,hb;
     29 
     30 	GET_FLOAT_WORD(ha,x);
     31 	ha &= 0x7fffffff;
     32 	GET_FLOAT_WORD(hb,y);
     33 	hb &= 0x7fffffff;
     34 	if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
     35 	SET_FLOAT_WORD(a,ha);	/* a <- |a| */
     36 	SET_FLOAT_WORD(b,hb);	/* b <- |b| */
     37 	if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */
     38 	k=0;
     39 	if(ha > 0x58800000) {	/* a>2**50 */
     40 	   if(ha >= 0x7f800000) {	/* Inf or NaN */
     41 	       w = a+b;			/* for sNaN */
     42 	       if(ha == 0x7f800000) w = a;
     43 	       if(hb == 0x7f800000) w = b;
     44 	       return w;
     45 	   }
     46 	   /* scale a and b by 2**-68 */
     47 	   ha -= 0x22000000; hb -= 0x22000000;	k += 68;
     48 	   SET_FLOAT_WORD(a,ha);
     49 	   SET_FLOAT_WORD(b,hb);
     50 	}
     51 	if(hb < 0x26800000) {	/* b < 2**-50 */
     52 	    if(hb <= 0x007fffff) {	/* subnormal b or 0 */
     53 	        if(hb==0) return a;
     54 		SET_FLOAT_WORD(t1,0x7e800000);	/* t1=2^126 */
     55 		b *= t1;
     56 		a *= t1;
     57 		k -= 126;
     58 	    } else {		/* scale a and b by 2^68 */
     59 	        ha += 0x22000000; 	/* a *= 2^68 */
     60 		hb += 0x22000000;	/* b *= 2^68 */
     61 		k -= 68;
     62 		SET_FLOAT_WORD(a,ha);
     63 		SET_FLOAT_WORD(b,hb);
     64 	    }
     65 	}
     66     /* medium size a and b */
     67 	w = a-b;
     68 	if (w>b) {
     69 	    SET_FLOAT_WORD(t1,ha&0xfffff000);
     70 	    t2 = a-t1;
     71 	    w  = __ieee754_sqrtf(t1*t1-(b*(-b)-t2*(a+t1)));
     72 	} else {
     73 	    a  = a+a;
     74 	    SET_FLOAT_WORD(yy1,hb&0xfffff000);
     75 	    y2 = b - yy1;
     76 	    SET_FLOAT_WORD(t1,ha+0x00800000);
     77 	    t2 = a - t1;
     78 	    w  = __ieee754_sqrtf(t1*yy1-(w*(-w)-(t1*y2+t2*b)));
     79 	}
     80 	if(k!=0) {
     81 	    SET_FLOAT_WORD(t1,0x3f800000+(k<<23));
     82 	    return t1*w;
     83 	} else return w;
     84 }
     85