gmp-4.3.1/mpz/dive_ui.c

/* mpz_divexact_ui -- exact division mpz by ulong.

Copyright 2001, 2002 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"

void
mpz_divexact_ui (mpz_ptr dst, mpz_srcptr src, unsigned long divisor)
{
  mp_size_t  size, abs_size;
  mp_ptr     dst_ptr;

  if (divisor == 0)
    DIVIDE_BY_ZERO;

  /* For nails don't try to be clever if d is bigger than a limb, just fake
     up an mpz_t and go to the main mpz_divexact.  */
  if (divisor > GMP_NUMB_MAX)
    {
      mp_limb_t  dlimbs[2];
      mpz_t      dz;
      ALLOC(dz) = 2;
      PTR(dz) = dlimbs;
      mpz_set_ui (dz, divisor);
      mpz_divexact (dst, src, dz);
      return;
    }

  size = SIZ(src);
  if (size == 0)
    {
      SIZ(dst) = 0;
      return;
    }
  abs_size = ABS (size);

  MPZ_REALLOC (dst, abs_size);
  dst_ptr = PTR(dst);

  MPN_DIVREM_OR_DIVEXACT_1 (dst_ptr, PTR(src), abs_size, (mp_limb_t) divisor);
  abs_size -= (dst_ptr[abs_size-1] == 0);
  SIZ(dst) = (size >= 0 ? abs_size : -abs_size);
}