113 lines
2.8 KiB
C
113 lines
2.8 KiB
C
/* mpz_cdiv_qr_ui -- Division rounding the quotient towards +infinity. The
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remainder gets the opposite sign as the denominator. In order to make it
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always fit into the return type, the negative of the true remainder is
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returned.
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Copyright 1994, 1995, 1996, 1999, 2001, 2002, 2004 Free Software Foundation,
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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 2.1 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; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "mpir.h"
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#include "gmp-impl.h"
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unsigned long int
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mpz_cdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
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{
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mp_size_t ns, nn, qn;
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mp_ptr np, qp;
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mp_limb_t rl;
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if (divisor == 0)
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DIVIDE_BY_ZERO;
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ns = SIZ(dividend);
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if (ns == 0)
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{
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SIZ(quot) = 0;
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SIZ(rem) = 0;
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return 0;
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}
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nn = ABS(ns);
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MPZ_REALLOC (quot, nn);
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qp = PTR(quot);
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np = PTR(dividend);
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#if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */
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if (divisor > GMP_NUMB_MAX)
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{
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mp_limb_t dp[2];
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mp_ptr rp;
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mp_size_t rn;
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MPZ_REALLOC (rem, 2);
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rp = PTR(rem);
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if (nn == 1) /* tdiv_qr requirements; tested above for 0 */
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{
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qp[0] = 0;
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qn = 1; /* a white lie, fixed below */
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rl = np[0];
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rp[0] = rl;
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}
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else
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{
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dp[0] = divisor & GMP_NUMB_MASK;
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dp[1] = divisor >> GMP_NUMB_BITS;
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mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
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rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
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qn = nn - 2 + 1;
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}
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if (rl != 0 && ns >= 0)
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{
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mpn_incr_u (qp, (mp_limb_t) 1);
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rl = divisor - rl;
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rp[0] = rl & GMP_NUMB_MASK;
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rp[1] = rl >> GMP_NUMB_BITS;
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}
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qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0;
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rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0);
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SIZ(rem) = -rn;
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}
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else
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#endif
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{
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rl = mpn_divrem_euclidean_qr_1 (qp, np, nn, (mp_limb_t) divisor);
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if (rl == 0)
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SIZ(rem) = 0;
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else
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{
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if (ns >= 0)
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{
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mpn_incr_u (qp, (mp_limb_t) 1);
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rl = divisor - rl;
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}
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PTR(rem)[0] = rl;
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SIZ(rem) = -(rl != 0);
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}
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qn = nn - (qp[nn - 1] == 0);
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}
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SIZ(quot) = ns >= 0 ? qn : -qn;
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return rl;
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}
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