libquadmath/math/frexpq.c

   1 /* frexpq.c -- __float128 version of s_frexp.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   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 /*
  17  * for non-zero x
  18  *      x = frexpq(arg,&exp);
  19  * return a __float128 fp quantity x such that 0.5 <= |x| <1.0
  20  * and the corresponding binary exponent "exp". That is
  21  *      arg = x*2^exp.
  22  * If arg is inf, 0.0, or NaN, then frexpq(arg,&exp) returns arg
  23  * with *exp=0.
  24  */
  25
  26 #include "quadmath-imp.h"
  27
  28 static const __float128
  29 two114 = 2.0769187434139310514121985316880384E+34Q; /* 0x4071000000000000, 0 */
  30
  31 __float128
  32 frexpq (__float128 x, int *eptr)
  33 {
  34   uint64_t hx, lx, ix;
  35   GET_FLT128_WORDS64(hx,lx,x);
  36   ix = 0x7fffffffffffffffULL&hx;
  37   *eptr = 0;
  38   if(ix>=0x7fff000000000000ULL||((ix|lx)==0)) return x; /* 0,inf,nan */
  39   if (ix<0x0001000000000000ULL) {               /* subnormal */
  40     x *= two114;
  41     GET_FLT128_MSW64(hx,x);
  42     ix = hx&0x7fffffffffffffffULL;
  43     *eptr = -114;
  44   }
  45   *eptr += (ix>>48)-16382;
  46   hx = (hx&0x8000ffffffffffffULL) | 0x3ffe000000000000ULL;
  47   SET_FLT128_MSW64(x,hx);
  48   return x;
  49 }