contrib/gmp/mpn/generic/dc_div_q.c

   1 /* mpn_dc_div_q -- divide-and-conquer division, returning exact quotient only.
   2
   3    Contributed to the GNU project by Torbjörn Granlund.
   4
   5    THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH A MUTABLE INTERFACE.  IT IS
   6    ONLY SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS
   7    ALMOST GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP
   8    RELEASE.
   9
  10 Copyright 2006, 2007 Free Software Foundation, Inc.
  11
  12 This file is part of the GNU MP Library.
  13
  14 The GNU MP Library is free software; you can redistribute it and/or modify
  15 it under the terms of the GNU Lesser General Public License as published by
  16 the Free Software Foundation; either version 3 of the License, or (at your
  17 option) any later version.
  18
  19 The GNU MP Library is distributed in the hope that it will be useful, but
  20 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  21 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  22 License for more details.
  23
  24 You should have received a copy of the GNU Lesser General Public License
  25 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  26
  27 #include "gmp.h"
  28 #include "gmp-impl.h"
  29
  30
  31 mp_limb_t
  32 mpn_dc_div_q (mp_ptr qp, mp_ptr np, mp_size_t nn, mp_srcptr dp, mp_size_t dn)
  33 {
  34   mp_ptr tp, wp;
  35   mp_limb_t qh;
  36   mp_size_t qn;
  37   TMP_DECL;
  38
  39   TMP_MARK;
  40
  41   tp = TMP_SALLOC_LIMBS (nn + 1);
  42   MPN_COPY (tp + 1, np, nn);
  43   tp[0] = 0;
  44
  45   qn = nn - dn;
  46   wp = TMP_SALLOC_LIMBS (qn + 1);
  47
  48   qh = mpn_dc_divappr_q (wp, tp, nn + 1, dp, dn);
  49
  50   if (wp[0] == 0)
  51     /* FIXME: Should multiply and subtract here, not recompute from scratch.  */
  52     qh = mpn_dc_div_qr (qp, np, nn, dp, dn);
  53   else
  54     MPN_COPY (qp, wp + 1, qn);
  55
  56   return qh;
  57 }