1  /* mpfr_cmpabs -- compare the absolute values of two FP numbers
       2  
       3  Copyright 1999, 2001-2004, 2006-2023 Free Software Foundation, Inc.
       4  Contributed by the AriC and Caramba projects, INRIA.
       5  
       6  This file is part of the GNU MPFR Library.
       7  
       8  The GNU MPFR Library is free software; you can redistribute it and/or modify
       9  it under the terms of the GNU Lesser General Public License as published by
      10  the Free Software Foundation; either version 3 of the License, or (at your
      11  option) any later version.
      12  
      13  The GNU MPFR Library is distributed in the hope that it will be useful, but
      14  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      15  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
      16  License for more details.
      17  
      18  You should have received a copy of the GNU Lesser General Public License
      19  along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
      20  https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
      21  51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
      22  
      23  #include "mpfr-impl.h"
      24  
      25  /* Return a positive value if abs(b) > abs(c), 0 if abs(b) = abs(c), and
      26     a negative value if abs(b) < abs(c). */
      27  
      28  int
      29  mpfr_cmpabs (mpfr_srcptr b, mpfr_srcptr c)
      30  {
      31    mpfr_exp_t be, ce;
      32    mp_size_t bn, cn;
      33    mp_limb_t *bp, *cp;
      34  
      35    if (MPFR_ARE_SINGULAR (b, c))
      36      {
      37        if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
      38          {
      39            MPFR_SET_ERANGEFLAG ();
      40            return 0;
      41          }
      42        else if (MPFR_IS_INF (b))
      43          return ! MPFR_IS_INF (c);
      44        else if (MPFR_IS_INF (c))
      45          return -1;
      46        else if (MPFR_IS_ZERO (c))
      47          return ! MPFR_IS_ZERO (b);
      48        else /* b == 0 */
      49          return -1;
      50      }
      51  
      52    MPFR_ASSERTD (MPFR_IS_PURE_FP (b));
      53    MPFR_ASSERTD (MPFR_IS_PURE_FP (c));
      54  
      55    /* Now that we know that b and c are pure FP numbers (i.e. they have
      56       a meaningful exponent), we use MPFR_EXP instead of MPFR_GET_EXP to
      57       allow exponents outside the current exponent range. For instance,
      58       this is useful for mpfr_pow, which compares values to __gmpfr_one.
      59       This is for internal use only! For compatibility with other MPFR
      60       versions, the user must still provide values that are representable
      61       in the current exponent range. */
      62    be = MPFR_EXP (b);
      63    ce = MPFR_EXP (c);
      64    if (be > ce)
      65      return 1;
      66    if (be < ce)
      67      return -1;
      68  
      69    /* exponents are equal */
      70  
      71    bn = MPFR_LIMB_SIZE(b)-1;
      72    cn = MPFR_LIMB_SIZE(c)-1;
      73  
      74    bp = MPFR_MANT(b);
      75    cp = MPFR_MANT(c);
      76  
      77    for ( ; bn >= 0 && cn >= 0; bn--, cn--)
      78      {
      79        if (bp[bn] > cp[cn])
      80          return 1;
      81        if (bp[bn] < cp[cn])
      82          return -1;
      83      }
      84  
      85    for ( ; bn >= 0; bn--)
      86      if (bp[bn])
      87        return 1;
      88  
      89    for ( ; cn >= 0; cn--)
      90      if (cp[cn])
      91        return -1;
      92  
      93     return 0;
      94  }