1  /* Copyright (C) 1996-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library.  If not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <math.h>
      19  #include "mathimpl.h"
      20  
      21  #ifndef SUFF
      22  #define SUFF
      23  #endif
      24  #ifndef float_type
      25  #define float_type double
      26  #endif
      27  
      28  #define CONCATX(a,b) __CONCAT(a,b)
      29  #define s(name) CONCATX(name,SUFF)
      30  #define m81(func) __m81_u(s(func))
      31  
      32  int
      33  s(__ieee754_ilogb) (float_type x)
      34  {
      35    float_type result;
      36    unsigned long x_cond;
      37  
      38    x_cond = __m81_test (x);
      39    /* We must return consistent values for zero and NaN.  */
      40    if (x_cond & __M81_COND_ZERO)
      41      return FP_ILOGB0;
      42    if (x_cond & (__M81_COND_NAN | __M81_COND_INF))
      43      return FP_ILOGBNAN;
      44  
      45    __asm ("fgetexp%.x %1, %0" : "=f" (result) : "f" (x));
      46    return (int) result;
      47  }