contrib/openbsd_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 "math.h"
  17 #include "math_private.h"
  18
  19 float
  20 hypotf(float x, float y)
  21 {
  22         float a=x,b=y,t1,t2,yy1,y2,w;
  23         int32_t j,k,ha,hb;
  24
  25         GET_FLOAT_WORD(ha,x);
  26         ha &= 0x7fffffff;
  27         GET_FLOAT_WORD(hb,y);
  28         hb &= 0x7fffffff;
  29         if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
  30         SET_FLOAT_WORD(a,ha);   /* a <- |a| */
  31         SET_FLOAT_WORD(b,hb);   /* b <- |b| */
  32         if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */
  33         k=0;
  34         if(ha > 0x58800000) {   /* a>2**50 */
  35            if(ha >= 0x7f800000) {       /* Inf or NaN */
  36                w = a+b;                 /* for sNaN */
  37                if(ha == 0x7f800000) w = a;
  38                if(hb == 0x7f800000) w = b;
  39                return w;
  40            }
  41            /* scale a and b by 2**-60 */
  42            ha -= 0x5d800000; hb -= 0x5d800000;  k += 60;
  43            SET_FLOAT_WORD(a,ha);
  44            SET_FLOAT_WORD(b,hb);
  45         }
  46         if(hb < 0x26800000) {   /* b < 2**-50 */
  47             if(hb <= 0x007fffff) {      /* subnormal b or 0 */
  48                 if(hb==0) return a;
  49                 SET_FLOAT_WORD(t1,0x3f000000);  /* t1=2^126 */
  50                 b *= t1;
  51                 a *= t1;
  52                 k -= 126;
  53             } else {            /* scale a and b by 2^60 */
  54                 ha += 0x5d800000;       /* a *= 2^60 */
  55                 hb += 0x5d800000;       /* b *= 2^60 */
  56                 k -= 60;
  57                 SET_FLOAT_WORD(a,ha);
  58                 SET_FLOAT_WORD(b,hb);
  59             }
  60         }
  61     /* medium size a and b */
  62         w = a-b;
  63         if (w>b) {
  64             SET_FLOAT_WORD(t1,ha&0xfffff000);
  65             t2 = a-t1;
  66             w  = sqrtf(t1*t1-(b*(-b)-t2*(a+t1)));
  67         } else {
  68             a  = a+a;
  69             SET_FLOAT_WORD(yy1,hb&0xfffff000);
  70             y2 = b - yy1;
  71             SET_FLOAT_WORD(t1,ha+0x00800000);
  72             t2 = a - t1;
  73             w  = sqrtf(t1*yy1-(w*(-w)-(t1*y2+t2*b)));
  74         }
  75         if(k!=0) {
  76             SET_FLOAT_WORD(t1,0x3f800000+(k<<23));
  77             return t1*w;
  78         } else return w;
  79 }