| Austin Schuh | bb1338c | 2024-06-15 19:31:16 -0700 | [diff] [blame] | 1 | /* mpq_mul -- multiply two rational numbers. |
| 2 | |
| 3 | Copyright 1991, 1994-1996, 2000-2002 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of the GNU MP Library. |
| 6 | |
| 7 | The GNU MP Library is free software; you can redistribute it and/or modify |
| 8 | it under the terms of either: |
| 9 | |
| 10 | * the GNU Lesser General Public License as published by the Free |
| 11 | Software Foundation; either version 3 of the License, or (at your |
| 12 | option) any later version. |
| 13 | |
| 14 | or |
| 15 | |
| 16 | * the GNU General Public License as published by the Free Software |
| 17 | Foundation; either version 2 of the License, or (at your option) any |
| 18 | later version. |
| 19 | |
| 20 | or both in parallel, as here. |
| 21 | |
| 22 | The GNU MP Library is distributed in the hope that it will be useful, but |
| 23 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 24 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 25 | for more details. |
| 26 | |
| 27 | You should have received copies of the GNU General Public License and the |
| 28 | GNU Lesser General Public License along with the GNU MP Library. If not, |
| 29 | see https://www.gnu.org/licenses/. */ |
| 30 | |
| 31 | #include "gmp-impl.h" |
| 32 | |
| 33 | |
| 34 | void |
| 35 | mpq_mul (mpq_ptr prod, mpq_srcptr op1, mpq_srcptr op2) |
| 36 | { |
| 37 | mpz_t gcd1, gcd2; |
| 38 | mpz_t tmp1, tmp2; |
| 39 | mp_size_t op1_num_size; |
| 40 | mp_size_t op1_den_size; |
| 41 | mp_size_t op2_num_size; |
| 42 | mp_size_t op2_den_size; |
| 43 | mp_size_t alloc; |
| 44 | TMP_DECL; |
| 45 | |
| 46 | if (op1 == op2) |
| 47 | { |
| 48 | /* No need for any GCDs when squaring. */ |
| 49 | mpz_mul (mpq_numref (prod), mpq_numref (op1), mpq_numref (op1)); |
| 50 | mpz_mul (mpq_denref (prod), mpq_denref (op1), mpq_denref (op1)); |
| 51 | return; |
| 52 | } |
| 53 | |
| 54 | op1_num_size = ABSIZ(NUM(op1)); |
| 55 | op1_den_size = SIZ(DEN(op1)); |
| 56 | op2_num_size = ABSIZ(NUM(op2)); |
| 57 | op2_den_size = SIZ(DEN(op2)); |
| 58 | |
| 59 | if (op1_num_size == 0 || op2_num_size == 0) |
| 60 | { |
| 61 | /* We special case this to simplify allocation logic; gcd(0,x) = x |
| 62 | is a singular case for the allocations. */ |
| 63 | SIZ(NUM(prod)) = 0; |
| 64 | MPZ_NEWALLOC (DEN(prod), 1)[0] = 1; |
| 65 | SIZ(DEN(prod)) = 1; |
| 66 | return; |
| 67 | } |
| 68 | |
| 69 | TMP_MARK; |
| 70 | |
| 71 | alloc = MIN (op1_num_size, op2_den_size); |
| 72 | MPZ_TMP_INIT (gcd1, alloc); |
| 73 | |
| 74 | alloc = MIN (op2_num_size, op1_den_size); |
| 75 | MPZ_TMP_INIT (gcd2, alloc); |
| 76 | |
| 77 | alloc = MAX (op1_num_size, op2_den_size); |
| 78 | MPZ_TMP_INIT (tmp1, alloc); |
| 79 | |
| 80 | alloc = MAX (op2_num_size, op1_den_size); |
| 81 | MPZ_TMP_INIT (tmp2, alloc); |
| 82 | |
| 83 | /* PROD might be identical to either operand, so don't store the result there |
| 84 | until we are finished with the input operands. We can overwrite the |
| 85 | numerator of PROD when we are finished with the numerators of OP1 and |
| 86 | OP2. */ |
| 87 | |
| 88 | mpz_gcd (gcd1, NUM(op1), DEN(op2)); |
| 89 | mpz_gcd (gcd2, NUM(op2), DEN(op1)); |
| 90 | |
| 91 | mpz_divexact_gcd (tmp1, NUM(op1), gcd1); |
| 92 | mpz_divexact_gcd (tmp2, NUM(op2), gcd2); |
| 93 | |
| 94 | mpz_mul (NUM(prod), tmp1, tmp2); |
| 95 | |
| 96 | mpz_divexact_gcd (tmp1, DEN(op2), gcd1); |
| 97 | mpz_divexact_gcd (tmp2, DEN(op1), gcd2); |
| 98 | |
| 99 | mpz_mul (DEN(prod), tmp1, tmp2); |
| 100 | |
| 101 | TMP_FREE; |
| 102 | } |