sysdeps/m68k/m680x0/fpu/s_logbl.c

   1 /* s_logbl.c -- long double version of s_logb.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 /*
  18  * long double logbl(x)
  19  * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
  20  * Use ilogb instead.
  21  */
  22
  23 #include <math.h>
  24 #include <math_private.h>
  25
  26 long double
  27 __logbl (long double x)
  28 {
  29   int32_t es, lx, ix;
  30
  31   GET_LDOUBLE_WORDS (es, ix, lx, x);
  32   es &= 0x7fff;                 /* exponent */
  33   if ((es | ix | lx) == 0)
  34     return -1.0 / fabsl (x);
  35   if (es == 0x7fff)
  36     return x * x;
  37   if (es == 0)                  /* IEEE 754 logb */
  38     {
  39       /* POSIX specifies that denormal number is treated as
  40          though it were normalized.  */
  41       if (ix == 0)
  42         es = -(__builtin_clz (lx) + 32);
  43       else
  44         es = -__builtin_clz (ix);
  45     }
  46   return (long double) (es - 16383);
  47 }
  48
  49 weak_alias (__logbl, logbl)