sysdeps/ieee754/ldbl-96/s_frexpl.c

   1 /* s_frexpl.c -- long double version of s_frexp.c.
   2  * Conversion to long double by Ulrich Drepper,
   3  * Cygnus Support, drepper@cygnus.com.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 static char rcsid[] = "$NetBSD: $";
  19 #endif
  20
  21 /*
  22  * for non-zero x
  23  *      x = frexpl(arg,&exp);
  24  * return a long double fp quantity x such that 0.5 <= |x| <1.0
  25  * and the corresponding binary exponent "exp". That is
  26  *      arg = x*2^exp.
  27  * If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
  28  * with *exp=0.
  29  */
  30
  31 #include <float.h>
  32 #include <math.h>
  33 #include <math_private.h>
  34
  35 static const long double
  36 #if LDBL_MANT_DIG == 64
  37 two65 =  3.68934881474191032320e+19L; /* 0x4040, 0x80000000, 0x00000000 */
  38 #else
  39 # error "Cannot handle this MANT_DIG"
  40 #endif
  41
  42
  43 long double __frexpl(long double x, int *eptr)
  44 {
  45         u_int32_t se, hx, ix, lx;
  46         GET_LDOUBLE_WORDS(se,hx,lx,x);
  47         ix = 0x7fff&se;
  48         *eptr = 0;
  49         if(ix==0x7fff||((ix|hx|lx)==0)) return x;       /* 0,inf,nan */
  50         if (ix==0x0000) {               /* subnormal */
  51             x *= two65;
  52             GET_LDOUBLE_EXP(se,x);
  53             ix = se&0x7fff;
  54             *eptr = -65;
  55         }
  56         *eptr += ix-16382;
  57         se = (se & 0x8000) | 0x3ffe;
  58         SET_LDOUBLE_EXP(x,se);
  59         return x;
  60 }
  61 weak_alias (__frexpl, frexpl)