1  /* s_ilogbl.c -- long double version of s_ilogb.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  /* ilogbl(long double x)
      21   * return the binary exponent of non-zero x
      22   * ilogbl(0) = FP_ILOGB0
      23   * ilogbl(NaN) = FP_ILOGBNAN (no signal is raised)
      24   * ilogbl(+-Inf) = INT_MAX (no signal is raised)
      25   */
      26  
      27  #include <math.h>
      28  #include "quadmath-imp.h"
      29  #ifndef FP_ILOGB0
      30  # define FP_ILOGB0 INT_MIN
      31  #endif
      32  #ifndef FP_ILOGBNAN
      33  # define FP_ILOGBNAN INT_MAX
      34  #endif
      35  
      36  int ilogbq (__float128 x)
      37  {
      38  	int64_t hx,lx;
      39  	int ix;
      40  
      41  	GET_FLT128_WORDS64(hx,lx,x);
      42  	hx &= 0x7fffffffffffffffLL;
      43  	if(hx <= 0x0001000000000000LL) {
      44  	    if((hx|lx)==0)
      45  		{ errno = EDOM; feraiseexcept (FE_INVALID); return FP_ILOGB0; }	/* ilogbl(0) = FP_ILOGB0 */
      46  	    else			/* subnormal x */
      47  		if(hx==0) {
      48  		    for (ix = -16431; lx>0; lx<<=1) ix -=1;
      49  		} else {
      50  		    for (ix = -16382, hx<<=15; hx>0; hx<<=1) ix -=1;
      51  		}
      52  	    return ix;
      53  	}
      54  	else if (hx<0x7fff000000000000LL) return (hx>>48)-0x3fff;
      55  	else if (FP_ILOGBNAN != INT_MAX) {
      56  	    /* ISO C99 requires ilogbl(+-Inf) == INT_MAX.  */
      57  	    if (((hx^0x7fff000000000000LL)|lx) == 0)
      58  		{ errno = EDOM; feraiseexcept (FE_INVALID); return INT_MAX; }
      59  	}
      60  	{ errno = EDOM; feraiseexcept (FE_INVALID); return FP_ILOGBNAN; }
      61  }