libquadmath/math/frexpq.c

   1 /* s_frexpl.c -- long double 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 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: $";
  18 #endif
  19
  20 /*
  21  * for non-zero x
  22  *      x = frexpq(arg,&exp);
  23  * return a long double fp quantity x such that 0.5 <= |x| <1.0
  24  * and the corresponding binary exponent "exp". That is
  25  *      arg = x*2^exp.
  26  * If arg is inf, 0.0, or NaN, then frexpq(arg,&exp) returns arg
  27  * with *exp=0.
  28  */
  29
  30 #include "quadmath-imp.h"
  31
  32 static const __float128
  33 two114 = 2.0769187434139310514121985316880384E+34Q; /* 0x4071000000000000, 0 */
  34
  35 __float128 frexpq(__float128 x, int *eptr)
  36 {
  37         uint64_t hx, lx, ix;
  38         GET_FLT128_WORDS64(hx,lx,x);
  39         ix = 0x7fffffffffffffffULL&hx;
  40         *eptr = 0;
  41         if(ix>=0x7fff000000000000ULL||((ix|lx)==0)) return x + x;/* 0,inf,nan */
  42         if (ix<0x0001000000000000ULL) {         /* subnormal */
  43             x *= two114;
  44             GET_FLT128_MSW64(hx,x);
  45             ix = hx&0x7fffffffffffffffULL;
  46             *eptr = -114;
  47         }
  48         *eptr += (ix>>48)-16382;
  49         hx = (hx&0x8000ffffffffffffULL) | 0x3ffe000000000000ULL;
  50         SET_FLT128_MSW64(x,hx);
  51         return x;
  52 }