sysdeps/m68k/m680x0/fpu/s_logbl.c

   1 /* s_logbl.c -- long double version of s_logb.c.
   2  */
   3
   4 /*
   5  * ====================================================
   6  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   7  *
   8  * Developed at SunPro, a Sun Microsystems, Inc. business.
   9  * Permission to use, copy, modify, and distribute this
  10  * software is freely granted, provided that this notice
  11  * is preserved.
  12  * ====================================================
  13  */
  14
  15 /*
  16  * long double logbl(x)
  17  * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
  18  * Use ilogb instead.
  19  */
  20
  21 #include <math.h>
  22 #include <math_private.h>
  23
  24 long double
  25 __logbl (long double x)
  26 {
  27   int32_t es, lx, ix;
  28
  29   GET_LDOUBLE_WORDS (es, ix, lx, x);
  30   es &= 0x7fff;                 /* exponent */
  31   if ((es | ix | lx) == 0)
  32     return -1.0 / fabsl (x);
  33   if (es == 0x7fff)
  34     return x * x;
  35   if (es == 0)                  /* IEEE 754 logb */
  36     {
  37       /* POSIX specifies that denormal number is treated as
  38          though it were normalized.  */
  39       if (ix == 0)
  40         es = -(__builtin_clz (lx) + 32);
  41       else
  42         es = -__builtin_clz (ix);
  43     }
  44   return (long double) (es - 16383);
  45 }
  46
  47 weak_alias (__logbl, logbl)