gcc/gmp/mpn/generic/bdiv_dbm1c.c

/* mpn_bdiv_dbm1c -- divide an mpn number by a divisor of B-1, where B is the
   limb base.  The dbm1c moniker means "Divisor of B Minus 1 with Carry".

   THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE.  IT IS ONLY
   SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS ALMOST
   GUARANTEED THAT IT'LL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.

Copyright 2008, 2009 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */

#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"


mp_limb_t
mpn_bdiv_dbm1c (mp_ptr qp, mp_srcptr ap, mp_size_t n, mp_limb_t bd, mp_limb_t h)
{
  mp_limb_t a, p0, p1, cy;
  mp_size_t i;

  for (i = 0; i < n; i++)
    {
      a = ap[i];
      umul_ppmm (p1, p0, a, bd << GMP_NAIL_BITS);
      p0 >>= GMP_NAIL_BITS;
      cy = h < p0;
      h = (h - p0) & GMP_NUMB_MASK;
      qp[i] = h;
      h = h - p1 - cy;
    }

  return h;
}