1 /* mpz_divexact -- finds quotient when known that quot * den == num && den != 0. 2 3 Contributed to the GNU project by Niels M�ller. 4 5 Copyright 1991, 1993, 1994, 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2005, 6 2006, 2007, 2009 Free Software Foundation, Inc. 7 8 This file is part of the GNU MP Library. 9 10 The GNU MP Library is free software; you can redistribute it and/or modify 11 it under the terms of the GNU Lesser General Public License as published by 12 the Free Software Foundation; either version 3 of the License, or (at your 13 option) any later version. 14 15 The GNU MP Library is distributed in the hope that it will be useful, but 16 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 17 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 18 License for more details. 19 20 You should have received a copy of the GNU Lesser General Public License 21 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 22 23 24 #include "gmp.h" 25 #include "gmp-impl.h" 26 #include "longlong.h" 27 28 void 29 mpz_divexact (mpz_ptr quot, mpz_srcptr num, mpz_srcptr den) 30 { 31 mp_ptr qp; 32 mp_size_t qn; 33 mp_srcptr np, dp; 34 mp_size_t nn, dn; 35 TMP_DECL; 36 37 #if WANT_ASSERT 38 { 39 mpz_t rem; 40 mpz_init (rem); 41 mpz_tdiv_r (rem, num, den); 42 ASSERT (SIZ(rem) == 0); 43 mpz_clear (rem); 44 } 45 #endif 46 47 nn = ABSIZ (num); 48 dn = ABSIZ (den); 49 50 qn = nn - dn + 1; 51 MPZ_REALLOC (quot, qn); 52 53 if (nn < dn) 54 { 55 /* This special case avoids segfaults below when the function is 56 incorrectly called with |N| < |D|, N != 0. It also handles the 57 well-defined case N = 0. */ 58 SIZ(quot) = 0; 59 return; 60 } 61 62 TMP_MARK; 63 64 qp = PTR(quot); 65 66 if (quot == num || quot == den) 67 qp = TMP_ALLOC_LIMBS (qn); 68 69 np = PTR(num); 70 dp = PTR(den); 71 72 mpn_divexact (qp, np, nn, dp, dn); 73 MPN_NORMALIZE (qp, qn); 74 75 SIZ(quot) = (SIZ(num) ^ SIZ(den)) >= 0 ? qn : -qn; 76 77 if (qp != PTR(quot)) 78 MPN_COPY (PTR(quot), qp, qn); 79 80 TMP_FREE; 81 } 82