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  * $FreeBSD: head/lib/msun/src/e_hypotf.c 226380 2011-10-15 07:00:28Z das $
  16  */
  17
  18 #include "math.h"
  19 #include "math_private.h"
  20
  21 float
  22 __ieee754_hypotf(float x, float y)
  23 {
  24         float a,b,t1,t2,y1,y2,w;
  25         int32_t j,k,ha,hb;
  26
  27         GET_FLOAT_WORD(ha,x);
  28         ha &= 0x7fffffff;
  29         GET_FLOAT_WORD(hb,y);
  30         hb &= 0x7fffffff;
  31         if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
  32         a = fabsf(a);
  33         b = fabsf(b);
  34         if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */
  35         k=0;
  36         if(ha > 0x58800000) {   /* a>2**50 */
  37            if(ha >= 0x7f800000) {       /* Inf or NaN */
  38                /* Use original arg order iff result is NaN; quieten sNaNs. */
  39                w = fabsf(x+0.0F)-fabsf(y+0.0F);
  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)&0xfffff000);
  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 }