Austin Schuh | dace2a6 | 2020-08-18 10:56:48 -0700 | [diff] [blame] | 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-impl.h" |
| 33 | |
| 34 | void |
| 35 | mpq_inv (mpq_ptr dest, mpq_srcptr src) |
| 36 | { |
| 37 | mp_size_t num_size = SIZ(NUM(src)); |
| 38 | mp_size_t den_size = SIZ(DEN(src)); |
| 39 | |
| 40 | if (num_size < 0) |
| 41 | { |
| 42 | num_size = -num_size; |
| 43 | den_size = -den_size; |
| 44 | } |
| 45 | else if (UNLIKELY (num_size == 0)) |
| 46 | DIVIDE_BY_ZERO; |
| 47 | |
| 48 | SIZ(DEN(dest)) = num_size; |
| 49 | SIZ(NUM(dest)) = den_size; |
| 50 | |
| 51 | /* If dest == src we may just swap the numerator and denominator; |
| 52 | we ensured that the new denominator is positive. */ |
| 53 | |
| 54 | if (dest == src) |
| 55 | { |
| 56 | MP_PTR_SWAP (PTR(NUM(dest)), PTR(DEN(dest))); |
| 57 | MP_SIZE_T_SWAP (ALLOC(NUM(dest)), ALLOC(DEN(dest))); |
| 58 | } |
| 59 | else |
| 60 | { |
| 61 | mp_ptr dp; |
| 62 | |
| 63 | den_size = ABS (den_size); |
| 64 | dp = MPZ_NEWALLOC (NUM(dest), den_size); |
| 65 | MPN_COPY (dp, PTR(DEN(src)), den_size); |
| 66 | |
| 67 | dp = MPZ_NEWALLOC (DEN(dest), num_size); |
| 68 | MPN_COPY (dp, PTR(NUM(src)), num_size); |
| 69 | } |
| 70 | } |