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 #ifdef __STDC__
  36 static const long double
  37 #else
  38 static long double
  39 #endif
  40 #if LDBL_MANT_DIG == 64
  41 two65 =  3.68934881474191032320e+19L; /* 0x4040, 0x80000000, 0x00000000 */
  42 #else
  43 # error "Cannot handle this MANT_DIG"
  44 #endif
  45
  46
  47 #ifdef __STDC__
  48         long double __frexpl(long double x, int *eptr)
  49 #else
  50         long double __frexpl(x, eptr)
  51         long double x; int *eptr;
  52 #endif
  53 {
  54         u_int32_t se, hx, ix, lx;
  55         GET_LDOUBLE_WORDS(se,hx,lx,x);
  56         ix = 0x7fff&se;
  57         *eptr = 0;
  58         if(ix==0x7fff||((ix|hx|lx)==0)) return x;       /* 0,inf,nan */
  59         if (ix==0x0000) {               /* subnormal */
  60             x *= two65;
  61             GET_LDOUBLE_EXP(se,x);
  62             ix = se&0x7fff;
  63             *eptr = -65;
  64         }
  65         *eptr += ix-16382;
  66         se = (se & 0x8000) | 0x3ffe;
  67         SET_LDOUBLE_EXP(x,se);
  68         return x;
  69 }
  70 weak_alias (__frexpl, frexpl)