1  /* Implement frexp for m68k.
       2     Copyright (C) 1996-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library.  If not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <math.h>
      20  
      21  FLOAT
      22  M_DECL_FUNC (__frexp) (FLOAT value, int *expptr)
      23  {
      24    FLOAT mantissa, exponent;
      25    int iexponent;
      26    unsigned long fpsr;
      27  
      28    __asm ("ftst%.x %1\n"
      29  	 "fmove%.l %/fpsr, %0"
      30  	 : "=dm" (fpsr) : "f" (value));
      31    if (fpsr & (7 << 24))
      32      {
      33        /* Not finite or zero.  */
      34        *expptr = 0;
      35        return value;
      36      }
      37    __asm ("fgetexp%.x %1, %0" : "=f" (exponent) : "f" (value));
      38    iexponent = (int) exponent + 1;
      39    *expptr = iexponent;
      40    __asm ("fscale%.l %2, %0"
      41  	 : "=f" (mantissa)
      42  	 : "0" (value), "dmi" (-iexponent));
      43    return mantissa;
      44  }
      45  declare_mgen_alias (__frexp, frexp)