github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpq/inv.c (about)

     1  /* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC
     2     with the numerator and denominator swapped.
     3  
     4  Copyright 1991, 1994, 1995, 2000, 2001, 2012 Free Software Foundation, Inc.
     5  
     6  This file is part of the GNU MP Library.
     7  
     8  The GNU MP Library is free software; you can redistribute it and/or modify
     9  it under the terms of either:
    10  
    11    * the GNU Lesser General Public License as published by the Free
    12      Software Foundation; either version 3 of the License, or (at your
    13      option) any later version.
    14  
    15  or
    16  
    17    * the GNU General Public License as published by the Free Software
    18      Foundation; either version 2 of the License, or (at your option) any
    19      later version.
    20  
    21  or both in parallel, as here.
    22  
    23  The GNU MP Library is distributed in the hope that it will be useful, but
    24  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    25  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    26  for more details.
    27  
    28  You should have received copies of the GNU General Public License and the
    29  GNU Lesser General Public License along with the GNU MP Library.  If not,
    30  see https://www.gnu.org/licenses/.  */
    31  
    32  #include "gmp.h"
    33  #include "gmp-impl.h"
    34  
    35  void
    36  mpq_inv (mpq_ptr dest, mpq_srcptr src)
    37  {
    38    mp_size_t num_size = SIZ(NUM(src));
    39    mp_size_t den_size = SIZ(DEN(src));
    40  
    41    if (num_size < 0)
    42      {
    43        num_size = -num_size;
    44        den_size = -den_size;
    45      }
    46    else if (UNLIKELY (num_size == 0))
    47      DIVIDE_BY_ZERO;
    48  
    49    SIZ(DEN(dest)) = num_size;
    50    SIZ(NUM(dest)) = den_size;
    51  
    52    /* If dest == src we may just swap the numerator and denominator;
    53       we ensured that the new denominator is positive.  */
    54  
    55    if (dest == src)
    56      {
    57        MP_PTR_SWAP (PTR(NUM(dest)), PTR(DEN(dest)));
    58        MP_SIZE_T_SWAP (ALLOC(NUM(dest)), ALLOC(DEN(dest)));
    59      }
    60    else
    61      {
    62        mp_ptr dp;
    63  
    64        den_size = ABS (den_size);
    65        dp = MPZ_NEWALLOC (NUM(dest), den_size);
    66        MPN_COPY (dp, PTR(DEN(src)), den_size);
    67  
    68        dp = MPZ_NEWALLOC (DEN(dest), num_size);
    69        MPN_COPY (dp, PTR(NUM(src)), num_size);
    70      }
    71  }