sysdeps/ieee754/ldbl-128/s_logbl.c

   1 /* s_logbl.c -- long double version of s_logb.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  * long double logbl(x)
  22  * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
  23  * Use ilogb instead.
  24  */
  25
  26 #include "math.h"
  27 #include "math_private.h"
  28
  29 #ifdef __STDC__
  30         long double __logbl(long double x)
  31 #else
  32         long double __logbl(x)
  33         long double x;
  34 #endif
  35 {
  36         int64_t lx,hx;
  37         GET_LDOUBLE_WORDS64(hx,lx,x);
  38         hx &= 0x7fffffffffffffffLL;             /* high |x| */
  39         if((hx|lx)==0) return -1.0/fabs(x);
  40         if(hx>=0x7fff000000000000LL) return x*x;
  41         if((hx>>=48)==0)                        /* IEEE 754 logb */
  42                 return -16382.0;
  43         else
  44                 return (long double) (hx-0x3fff);
  45 }
  46 weak_alias (__logbl, logbl)