82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
/* mpz_divexact -- finds quotient when known that quot * den == num && den != 0.
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Contributed to the GNU project by Niels Möller.
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Copyright 1991, 1993, 1994, 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2005,
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2006, 2007, 2009 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
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#include "mpir.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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void
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mpz_divexact (mpz_ptr quot, mpz_srcptr num, mpz_srcptr den)
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{
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mp_ptr qp;
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mp_size_t qn;
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mp_srcptr np, dp;
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mp_size_t nn, dn;
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TMP_DECL;
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#if WANT_ASSERT
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{
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mpz_t rem;
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mpz_init (rem);
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mpz_tdiv_r (rem, num, den);
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ASSERT (SIZ(rem) == 0);
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mpz_clear (rem);
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}
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#endif
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nn = ABSIZ (num);
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dn = ABSIZ (den);
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qn = nn - dn + 1;
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MPZ_REALLOC (quot, qn);
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if (nn < dn)
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{
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/* This special case avoids segfaults below when the function is
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incorrectly called with |N| < |D|, N != 0. It also handles the
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well-defined case N = 0. */
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SIZ(quot) = 0;
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return;
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}
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TMP_MARK;
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qp = PTR(quot);
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if (quot == num || quot == den)
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qp = TMP_ALLOC_LIMBS (qn);
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np = PTR(num);
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dp = PTR(den);
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mpn_divexact (qp, np, nn, dp, dn);
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MPN_NORMALIZE (qp, qn);
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SIZ(quot) = (SIZ(num) ^ SIZ(den)) >= 0 ? qn : -qn;
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if (qp != PTR(quot))
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MPN_COPY (PTR(quot), qp, qn);
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TMP_FREE;
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}
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