toolchain/gcc/newlib/libm/math/ef_hypot.c

   1 /* ef_hypot.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 "fdlibm.h"
  17
  18 #ifdef __STDC__
  19         float __ieee754_hypotf(float x, float y)
  20 #else
  21         float __ieee754_hypotf(x,y)
  22         float x, y;
  23 #endif
  24 {
  25         float a=x,b=y,t1,t2,y1,y2,w;
  26         __int32_t j,k,ha,hb;
  27
  28         GET_FLOAT_WORD(ha,x);
  29         ha &= 0x7fffffffL;
  30         GET_FLOAT_WORD(hb,y);
  31         hb &= 0x7fffffffL;
  32         if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
  33         SET_FLOAT_WORD(a,ha);   /* a <- |a| */
  34         SET_FLOAT_WORD(b,hb);   /* b <- |b| */
  35         if((ha-hb)>0xf000000L) {return a+b;} /* x/y > 2**30 */
  36         k=0;
  37         if(ha > 0x58800000L) {  /* a>2**50 */
  38            if(!FLT_UWORD_IS_FINITE(ha)) {       /* Inf or NaN */
  39                w = a+b;                 /* for sNaN */
  40                if(FLT_UWORD_IS_INFINITE(ha)) w = a;
  41                if(FLT_UWORD_IS_INFINITE(hb)) w = b;
  42                return w;
  43            }
  44            /* scale a and b by 2**-68 */
  45            ha -= 0x22000000L; hb -= 0x22000000L;        k += 68;
  46            SET_FLOAT_WORD(a,ha);
  47            SET_FLOAT_WORD(b,hb);
  48         }
  49         if(hb < 0x26800000L) {  /* b < 2**-50 */
  50             if(FLT_UWORD_IS_ZERO(hb)) {
  51                 return a;
  52             } else if(FLT_UWORD_IS_SUBNORMAL(hb)) {
  53                 SET_FLOAT_WORD(t1,0x3f000000L); /* 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&0xfffff000L);
  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&0xfffff000L);
  74             y2 = b - y1;
  75             SET_FLOAT_WORD(t1,ha+0x00800000L);
  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(t1,0x3f800000L+(k<<23));
  81             return t1*w;
  82         } else return w;
  83 }