1  /* mpfr_cmp -- compare two floating-point numbers
       2  
       3  Copyright 1999, 2001, 2003-2023 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  /* returns 0 iff b = sign(s) * c
      26             a positive value iff b > sign(s) * c
      27             a negative value iff b < sign(s) * c
      28     returns 0 and sets erange flag if b and/or c is NaN.
      29  */
      30  
      31  MPFR_HOT_FUNCTION_ATTR int
      32  mpfr_cmp3 (mpfr_srcptr b, mpfr_srcptr c, int s)
      33  {
      34    mpfr_exp_t be, ce;
      35    mp_size_t bn, cn;
      36    mp_limb_t *bp, *cp;
      37  
      38    s = MPFR_MULT_SIGN(s, MPFR_SIGN(c));
      39  
      40    if (MPFR_ARE_SINGULAR(b, c))
      41      {
      42        if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
      43          {
      44            MPFR_SET_ERANGEFLAG ();
      45            return 0;
      46          }
      47        else if (MPFR_IS_INF(b))
      48          {
      49            if (MPFR_IS_INF(c) && s == MPFR_SIGN(b) )
      50              return 0;
      51            else
      52              return MPFR_SIGN(b);
      53          }
      54        else if (MPFR_IS_INF(c))
      55          return -s;
      56        else if (MPFR_IS_ZERO(b))
      57          return MPFR_IS_ZERO(c) ? 0 : -s;
      58        else /* necessarily c=0 */
      59          return MPFR_SIGN(b);
      60      }
      61    /* b and c are real numbers */
      62    if (s != MPFR_SIGN(b))
      63      return MPFR_SIGN(b);
      64  
      65    /* now signs are equal */
      66  
      67    be = MPFR_GET_EXP (b);
      68    ce = MPFR_GET_EXP (c);
      69    if (be > ce)
      70      return s;
      71    if (be < ce)
      72      return -s;
      73  
      74    /* both signs and exponents are equal */
      75  
      76    bn = MPFR_LAST_LIMB (b);
      77    cn = MPFR_LAST_LIMB (c);
      78  
      79    bp = MPFR_MANT(b);
      80    cp = MPFR_MANT(c);
      81  
      82    for ( ; bn >= 0 && cn >= 0; bn--, cn--)
      83      {
      84        if (bp[bn] > cp[cn])
      85          return s;
      86        if (bp[bn] < cp[cn])
      87          return -s;
      88      }
      89    for ( ; bn >= 0; bn--)
      90      if (bp[bn])
      91        return s;
      92    for ( ; cn >= 0; cn--)
      93      if (cp[cn])
      94        return -s;
      95  
      96     return 0;
      97  }
      98  
      99  #undef mpfr_cmp
     100  int
     101  mpfr_cmp (mpfr_srcptr b, mpfr_srcptr c)
     102  {
     103    return mpfr_cmp3 (b, c, 1);
     104  }