1 /* mpq_div -- divide two rational numbers. 2 3 Copyright 1991, 1994-1996, 2000, 2001, 2015 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.h" 32 #include "gmp-impl.h" 33 34 35 void 36 mpq_div (mpq_ptr quot, mpq_srcptr op1, mpq_srcptr op2) 37 { 38 mpz_t gcd1, gcd2; 39 mpz_t tmp1, tmp2; 40 mp_size_t op1_size; 41 mp_size_t op2_size; 42 mp_size_t alloc; 43 TMP_DECL; 44 45 op2_size = SIZ(NUM(op2)); 46 47 if (UNLIKELY (op2_size == 0)) 48 DIVIDE_BY_ZERO; 49 50 if (UNLIKELY (quot == op2)) 51 { 52 if (op1 == op2) 53 { 54 PTR(NUM(quot))[0] = 1; 55 SIZ(NUM(quot)) = 1; 56 PTR(DEN(quot))[0] = 1; 57 SIZ(DEN(quot)) = 1; 58 return; 59 } 60 61 /* We checked for op1 == op2: we are not in the x=x/x case. 62 We compute x=y/x by computing x=inv(x)*y */ 63 MPN_PTR_SWAP (PTR(NUM(quot)), ALLOC(NUM(quot)), 64 PTR(DEN(quot)), ALLOC(DEN(quot))); 65 if (op2_size > 0) 66 { 67 SIZ(NUM(quot)) = SIZ(DEN(quot)); 68 SIZ(DEN(quot)) = op2_size; 69 } 70 else 71 { 72 SIZ(NUM(quot)) = - SIZ(DEN(quot)); 73 SIZ(DEN(quot)) = - op2_size; 74 } 75 mpq_mul (quot, quot, op1); 76 return; 77 } 78 79 op1_size = ABSIZ(NUM(op1)); 80 81 if (op1_size == 0) 82 { 83 /* We special case this to simplify allocation logic; gcd(0,x) = x 84 is a singular case for the allocations. */ 85 SIZ(NUM(quot)) = 0; 86 PTR(DEN(quot))[0] = 1; 87 SIZ(DEN(quot)) = 1; 88 return; 89 } 90 91 op2_size = ABS(op2_size); 92 93 TMP_MARK; 94 95 alloc = MIN (op1_size, op2_size); 96 MPZ_TMP_INIT (gcd1, alloc); 97 98 alloc = MAX (op1_size, op2_size); 99 MPZ_TMP_INIT (tmp1, alloc); 100 101 op2_size = SIZ(DEN(op2)); 102 op1_size = SIZ(DEN(op1)); 103 104 alloc = MIN (op1_size, op2_size); 105 MPZ_TMP_INIT (gcd2, alloc); 106 107 alloc = MAX (op1_size, op2_size); 108 MPZ_TMP_INIT (tmp2, alloc); 109 110 /* QUOT might be identical to OP1, so don't store the result there 111 until we are finished with the input operand. We can overwrite 112 the numerator of QUOT when we are finished with the numerator of 113 OP1. */ 114 115 mpz_gcd (gcd1, NUM(op1), NUM(op2)); 116 mpz_gcd (gcd2, DEN(op2), DEN(op1)); 117 118 mpz_divexact_gcd (tmp1, NUM(op1), gcd1); 119 mpz_divexact_gcd (tmp2, DEN(op2), gcd2); 120 121 mpz_mul (NUM(quot), tmp1, tmp2); 122 123 mpz_divexact_gcd (tmp1, NUM(op2), gcd1); 124 mpz_divexact_gcd (tmp2, DEN(op1), gcd2); 125 126 mpz_mul (DEN(quot), tmp1, tmp2); 127 128 /* Keep the denominator positive. */ 129 if (SIZ(DEN(quot)) < 0) 130 { 131 SIZ(DEN(quot)) = -SIZ(DEN(quot)); 132 SIZ(NUM(quot)) = -SIZ(NUM(quot)); 133 } 134 135 TMP_FREE; 136 } 137