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Annotation of OpenXM_contrib/gmp/mpz/cdiv_q_ui.c, Revision 1.1.1.3

1.1       maekawa     1: /* mpz_cdiv_q_ui -- Division rounding the quotient towards +infinity.  The
                      2:    remainder gets the opposite sign as the denominator.  In order to make it
                      3:    always fit into the return type, the negative of the true remainder is
                      4:    returned.
                      5:
1.1.1.3 ! ohara       6: Copyright 1994, 1996, 1999, 2001, 2002 Free Software Foundation, Inc.
1.1       maekawa     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
1.1.1.2   maekawa    11: it under the terms of the GNU Lesser General Public License as published by
                     12: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    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
1.1.1.2   maekawa    17: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    18: License for more details.
                     19:
1.1.1.2   maekawa    20: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    21: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     22: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     23: MA 02111-1307, USA. */
                     24:
                     25: #include "gmp.h"
                     26: #include "gmp-impl.h"
                     27:
                     28: unsigned long int
                     29: mpz_cdiv_q_ui (mpz_ptr quot, mpz_srcptr dividend, unsigned long int divisor)
                     30: {
1.1.1.3 ! ohara      31:   mp_size_t ns, nn, qn;
        !            32:   mp_ptr np, qp;
        !            33:   mp_limb_t rl;
1.1       maekawa    34:
1.1.1.2   maekawa    35:   if (divisor == 0)
                     36:     DIVIDE_BY_ZERO;
                     37:
1.1.1.3 ! ohara      38:   ns = SIZ(dividend);
        !            39:   if (ns == 0)
        !            40:     {
        !            41:       SIZ(quot) = 0;
        !            42:       return 0;
        !            43:     }
1.1       maekawa    44:
1.1.1.3 ! ohara      45:   nn = ABS(ns);
        !            46:   MPZ_REALLOC (quot, nn);
        !            47:   qp = PTR(quot);
        !            48:   np = PTR(dividend);
1.1       maekawa    49:
1.1.1.3 ! ohara      50: #if GMP_NAIL_BITS != 0
        !            51:   if (divisor > GMP_NUMB_MAX)
        !            52:     {
        !            53:       mp_limb_t dp[2], rp[2];
1.1       maekawa    54:
1.1.1.3 ! ohara      55:       if (nn == 1)             /* tdiv_qr requirements; tested above for 0 */
        !            56:        {
        !            57:          qp[0] = 0;
        !            58:          rl = np[0];
        !            59:          qn = 1;               /* a white lie, fixed below */
        !            60:        }
        !            61:       else
        !            62:        {
        !            63:          dp[0] = divisor & GMP_NUMB_MASK;
        !            64:          dp[1] = divisor >> GMP_NUMB_BITS;
        !            65:          mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
        !            66:          rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
        !            67:          qn = nn - 2 + 1;
        !            68:        }
        !            69:
        !            70:       if (rl != 0 && ns >= 0)
        !            71:        {
        !            72:          mpn_incr_u (qp, (mp_limb_t) 1);
        !            73:          rl = divisor - rl;
        !            74:        }
1.1       maekawa    75:
1.1.1.3 ! ohara      76:       qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0;
1.1       maekawa    77:     }
1.1.1.3 ! ohara      78:   else
        !            79: #endif
        !            80:     {
        !            81:       rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor);
1.1       maekawa    82:
1.1.1.3 ! ohara      83:       if (rl != 0 && ns >= 0)
        !            84:        {
        !            85:          mpn_incr_u (qp, (mp_limb_t) 1);
        !            86:          rl = divisor - rl;
        !            87:        }
        !            88:
        !            89:       qn = nn - (qp[nn - 1] == 0);
        !            90:     }
1.1       maekawa    91:
1.1.1.3 ! ohara      92:   SIZ(quot) = ns >= 0 ? qn : -qn;
        !            93:   return rl;
1.1       maekawa    94: }