modules/fdlibm/src/e_hypotf.cpp

   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 //__FBSDID("$FreeBSD$");
  18
  19 #include "math.h"
  20 #include "math_private.h"
  21
  22 float
  23 __ieee754_hypotf(float x, float y)
  24 {
  25         float a,b,t1,t2,y1,y2,w;
  26         int32_t j,k,ha,hb;
  27
  28         GET_FLOAT_WORD(ha,x);
  29         ha &= 0x7fffffff;
  30         GET_FLOAT_WORD(hb,y);
  31         hb &= 0x7fffffff;
  32         if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
  33         a = fabsf(a);
  34         b = fabsf(b);
  35         if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */
  36         k=0;
  37         if(ha > 0x58800000) {   /* a>2**50 */
  38            if(ha >= 0x7f800000) {       /* Inf or NaN */
  39                /* Use original arg order iff result is NaN; quieten sNaNs. */
  40                w = fabsl(x+0.0L)-fabsf(y+0);
  41                if(ha == 0x7f800000) w = a;
  42                if(hb == 0x7f800000) w = b;
  43                return w;
  44            }
  45            /* scale a and b by 2**-68 */
  46            ha -= 0x22000000; hb -= 0x22000000;  k += 68;
  47            SET_FLOAT_WORD(a,ha);
  48            SET_FLOAT_WORD(b,hb);
  49         }
  50         if(hb < 0x26800000) {   /* b < 2**-50 */
  51             if(hb <= 0x007fffff) {      /* subnormal b or 0 */
  52                 if(hb==0) return a;
  53                 SET_FLOAT_WORD(t1,0x7e800000);  /* t1=2^126 */
  54                 b *= t1;
  55                 a *= t1;
  56                 k -= 126;
  57             } else {            /* scale a and b by 2^68 */
  58                 ha += 0x22000000;       /* a *= 2^68 */
  59                 hb += 0x22000000;       /* b *= 2^68 */
  60                 k -= 68;
  61                 SET_FLOAT_WORD(a,ha);
  62                 SET_FLOAT_WORD(b,hb);
  63             }
  64         }
  65     /* medium size a and b */
  66         w = a-b;
  67         if (w>b) {
  68             SET_FLOAT_WORD(t1,ha&0xfffff000);
  69             t2 = a-t1;
  70             w  = __ieee754_sqrtf(t1*t1-(b*(-b)-t2*(a+t1)));
  71         } else {
  72             a  = a+a;
  73             SET_FLOAT_WORD(y1,hb&0xfffff000);
  74             y2 = b - y1;
  75             SET_FLOAT_WORD(t1,(ha+0x00800000)&0xfffff000);
  76             t2 = a - t1;
  77             w  = __ieee754_sqrtf(t1*y1-(w*(-w)-(t1*y2+t2*b)));
  78         }
  79         if(k!=0) {
  80             SET_FLOAT_WORD(t1,(127+k)<<23);
  81             return t1*w;
  82         } else return w;
  83 }