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Annotation of OpenXM_contrib/gmp/mpq/inv.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC
                      2:    with the numerator and denominator swapped.
                      3:
1.1.1.3 ! ohara       4: Copyright 1991, 1994, 1995, 2000, 2001 Free Software Foundation, Inc.
1.1       maekawa     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
1.1.1.2   maekawa     9: it under the terms of the GNU Lesser General Public License as published by
                     10: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    11: option) any later version.
                     12:
                     13: The GNU MP Library is distributed in the hope that it will be useful, but
                     14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.1.1.2   maekawa    15: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    16: License for more details.
                     17:
1.1.1.2   maekawa    18: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    19: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     21: MA 02111-1307, USA. */
                     22:
                     23: #include "gmp.h"
                     24: #include "gmp-impl.h"
                     25:
                     26: void
                     27: mpq_inv (MP_RAT *dest, const MP_RAT *src)
                     28: {
                     29:   mp_size_t num_size = src->_mp_num._mp_size;
                     30:   mp_size_t den_size = src->_mp_den._mp_size;
                     31:
                     32:   if (num_size == 0)
1.1.1.2   maekawa    33:     DIVIDE_BY_ZERO;
1.1       maekawa    34:
                     35:   if (num_size < 0)
                     36:     {
                     37:       num_size = -num_size;
                     38:       den_size = -den_size;
                     39:     }
                     40:   dest->_mp_den._mp_size = num_size;
                     41:   dest->_mp_num._mp_size = den_size;
                     42:
                     43:   /* If dest == src we may just swap the numerator and denominator, but
                     44:      we have to ensure the new denominator is positive.  */
                     45:
                     46:   if (dest == src)
                     47:     {
                     48:       mp_size_t alloc = dest->_mp_num._mp_alloc;
                     49:       mp_ptr limb_ptr = dest->_mp_num._mp_d;
                     50:
                     51:       dest->_mp_num._mp_alloc = dest->_mp_den._mp_alloc;
                     52:       dest->_mp_num._mp_d = dest->_mp_den._mp_d;
                     53:
                     54:       dest->_mp_den._mp_alloc = alloc;
                     55:       dest->_mp_den._mp_d = limb_ptr;
                     56:     }
                     57:   else
                     58:     {
                     59:       den_size = ABS (den_size);
                     60:       if (dest->_mp_num._mp_alloc < den_size)
                     61:        _mpz_realloc (&(dest->_mp_num), den_size);
                     62:
                     63:       if (dest->_mp_den._mp_alloc < num_size)
                     64:        _mpz_realloc (&(dest->_mp_den), num_size);
                     65:
                     66:       MPN_COPY (dest->_mp_num._mp_d, src->_mp_den._mp_d, den_size);
                     67:       MPN_COPY (dest->_mp_den._mp_d, src->_mp_num._mp_d, num_size);
                     68:     }
                     69: }