1/* mpz_divexact -- finds quotient when known that quot * den == num && den != 0. 2 3Contributed to the GNU project by Niels M��ller. 4 5Copyright 1991, 1993-1998, 2000-2002, 2005-2007, 2009, 2012 Free Software 6Foundation, Inc. 7 8This file is part of the GNU MP Library. 9 10The GNU MP Library is free software; you can redistribute it and/or modify 11it under the terms of either: 12 13 * the GNU Lesser General Public License as published by the Free 14 Software Foundation; either version 3 of the License, or (at your 15 option) any later version. 16 17or 18 19 * the GNU General Public License as published by the Free Software 20 Foundation; either version 2 of the License, or (at your option) any 21 later version. 22 23or both in parallel, as here. 24 25The GNU MP Library is distributed in the hope that it will be useful, but 26WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 27or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 28for more details. 29 30You should have received copies of the GNU General Public License and the 31GNU Lesser General Public License along with the GNU MP Library. If not, 32see https://www.gnu.org/licenses/. */ 33 34 35#include "gmp-impl.h" 36 37void 38mpz_divexact (mpz_ptr quot, mpz_srcptr num, mpz_srcptr den) 39{ 40 mp_ptr qp; 41 mp_size_t qn; 42 mp_srcptr np, dp; 43 mp_size_t nn, dn; 44 TMP_DECL; 45 46#if WANT_ASSERT 47 { 48 mpz_t rem; 49 mpz_init (rem); 50 mpz_tdiv_r (rem, num, den); 51 ASSERT (SIZ(rem) == 0); 52 mpz_clear (rem); 53 } 54#endif 55 56 nn = ABSIZ (num); 57 dn = ABSIZ (den); 58 59 if (nn < dn) 60 { 61 /* This special case avoids segfaults below when the function is 62 incorrectly called with |N| < |D|, N != 0. It also handles the 63 well-defined case N = 0. */ 64 SIZ(quot) = 0; 65 return; 66 } 67 68 qn = nn - dn + 1; 69 70 TMP_MARK; 71 72 if (quot == num || quot == den) 73 qp = TMP_ALLOC_LIMBS (qn); 74 else 75 qp = MPZ_NEWALLOC (quot, qn); 76 77 np = PTR(num); 78 dp = PTR(den); 79 80 mpn_divexact (qp, np, nn, dp, dn); 81 MPN_NORMALIZE (qp, qn); 82 83 if (qp != PTR(quot)) 84 MPN_COPY (MPZ_NEWALLOC (quot, qn), qp, qn); 85 86 SIZ(quot) = (SIZ(num) ^ SIZ(den)) >= 0 ? qn : -qn; 87 88 TMP_FREE; 89} 90