contrib/gmp/mpz/tdiv_ui.c

   1 /* mpz_tdiv_ui(dividend, divisor_limb) -- Return DIVDEND mod DIVISOR_LIMB.
   2
   3 Copyright 1991, 1993, 1994, 1996, 1997, 1998, 2001, 2002, 2004, 2005 Free
   4 Software Foundation, Inc.
   5
   6 This file is part of the GNU MP Library.
   7
   8 The GNU MP Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MP Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  20
  21 #include "gmp.h"
  22 #include "gmp-impl.h"
  23 #include "longlong.h"
  24
  25 unsigned long int
  26 mpz_tdiv_ui (mpz_srcptr dividend, unsigned long int divisor)
  27 {
  28   mp_size_t ns, nn;
  29   mp_ptr np;
  30   mp_limb_t rl;
  31
  32   if (divisor == 0)
  33     DIVIDE_BY_ZERO;
  34
  35   ns = SIZ(dividend);
  36   if (ns == 0)
  37     {
  38       return 0;
  39     }
  40
  41   nn = ABS(ns);
  42   np = PTR(dividend);
  43
  44 #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
  45   if (divisor > GMP_NUMB_MAX)
  46     {
  47       mp_limb_t dp[2], rp[2];
  48       mp_ptr qp;
  49       mp_size_t rn;
  50       TMP_DECL;
  51
  52       if (nn == 1)              /* tdiv_qr requirements; tested above for 0 */
  53         {
  54           rl = np[0];
  55           return rl;
  56         }
  57
  58       TMP_MARK;
  59       dp[0] = divisor & GMP_NUMB_MASK;
  60       dp[1] = divisor >> GMP_NUMB_BITS;
  61       qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
  62       mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
  63       TMP_FREE;
  64       rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
  65       rn = 2 - (rp[1] == 0);  rn -= (rp[rn - 1] == 0);
  66     }
  67   else
  68 #endif
  69     {
  70       rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
  71     }
  72
  73   return rl;
  74 }