lib/libm/src/e_hypotf.c

   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 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: e_hypotf.c,v 1.9 2008/04/25 22:21:53 christos 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**-60 */
  47            ha -= 0x5d800000; hb -= 0x5d800000;  k += 60;
  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(t1,0x3f000000);  /* t1=2^126 */
  55                 b *= t1;
  56                 a *= t1;
  57                 k -= 126;
  58             } else {            /* scale a and b by 2^60 */
  59                 ha += 0x5d800000;       /* a *= 2^60 */
  60                 hb += 0x5d800000;       /* b *= 2^60 */
  61                 k -= 60;
  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 }