1 /* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC
2 with the numerator and denominator swapped.
4 Copyright (C) 1991, 1994, 1995 Free Software Foundation, Inc.
6 This file is part of the GNU MP Library.
8 The GNU MP Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Library General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or (at your
11 option) any later version.
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
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
16 License for more details.
18 You should have received a copy of the GNU Library General Public License
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. */
28 mpq_inv (MP_RAT *dest, const MP_RAT *src)
35 mp_size_t num_size = src->_mp_num._mp_size;
36 mp_size_t den_size = src->_mp_den._mp_size;
39 num_size = 1 / num_size; /* Divide by zero! */
46 dest->_mp_den._mp_size = num_size;
47 dest->_mp_num._mp_size = den_size;
49 /* If dest == src we may just swap the numerator and denominator, but
50 we have to ensure the new denominator is positive. */
54 mp_size_t alloc = dest->_mp_num._mp_alloc;
55 mp_ptr limb_ptr = dest->_mp_num._mp_d;
57 dest->_mp_num._mp_alloc = dest->_mp_den._mp_alloc;
58 dest->_mp_num._mp_d = dest->_mp_den._mp_d;
60 dest->_mp_den._mp_alloc = alloc;
61 dest->_mp_den._mp_d = limb_ptr;
65 den_size = ABS (den_size);
66 if (dest->_mp_num._mp_alloc < den_size)
67 _mpz_realloc (&(dest->_mp_num), den_size);
69 if (dest->_mp_den._mp_alloc < num_size)
70 _mpz_realloc (&(dest->_mp_den), num_size);
72 MPN_COPY (dest->_mp_num._mp_d, src->_mp_den._mp_d, den_size);
73 MPN_COPY (dest->_mp_den._mp_d, src->_mp_num._mp_d, num_size);