| /* mpq_inv(dest,src) -- invert a rational number, i.e. set DEST to SRC |
| with the numerator and denominator swapped. |
| |
| Copyright 1991, 1994, 1995, 2000, 2001 Free Software Foundation, Inc. |
| |
| This file is part of the GNU MP Library. |
| |
| The GNU MP Library is free software; you can redistribute it and/or modify |
| it under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or (at your |
| option) any later version. |
| |
| The GNU MP Library is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ |
| |
| #include "gmp.h" |
| #include "gmp-impl.h" |
| |
| void |
| mpq_inv (MP_RAT *dest, const MP_RAT *src) |
| { |
| mp_size_t num_size = src->_mp_num._mp_size; |
| mp_size_t den_size = src->_mp_den._mp_size; |
| |
| if (num_size == 0) |
| DIVIDE_BY_ZERO; |
| |
| if (num_size < 0) |
| { |
| num_size = -num_size; |
| den_size = -den_size; |
| } |
| dest->_mp_den._mp_size = num_size; |
| dest->_mp_num._mp_size = den_size; |
| |
| /* If dest == src we may just swap the numerator and denominator, but |
| we have to ensure the new denominator is positive. */ |
| |
| if (dest == src) |
| { |
| mp_size_t alloc = dest->_mp_num._mp_alloc; |
| mp_ptr limb_ptr = dest->_mp_num._mp_d; |
| |
| dest->_mp_num._mp_alloc = dest->_mp_den._mp_alloc; |
| dest->_mp_num._mp_d = dest->_mp_den._mp_d; |
| |
| dest->_mp_den._mp_alloc = alloc; |
| dest->_mp_den._mp_d = limb_ptr; |
| } |
| else |
| { |
| den_size = ABS (den_size); |
| if (dest->_mp_num._mp_alloc < den_size) |
| _mpz_realloc (&(dest->_mp_num), den_size); |
| |
| if (dest->_mp_den._mp_alloc < num_size) |
| _mpz_realloc (&(dest->_mp_den), num_size); |
| |
| MPN_COPY (dest->_mp_num._mp_d, src->_mp_den._mp_d, den_size); |
| MPN_COPY (dest->_mp_den._mp_d, src->_mp_num._mp_d, num_size); |
| } |
| } |