source/libs/gmp/gmp-src/mpz/tdiv_qr_ui.c

   1 /* mpz_tdiv_qr_ui(quot,rem,dividend,short_divisor) --
   2    Set QUOT to DIVIDEND / SHORT_DIVISOR
   3    and REM to DIVIDEND mod SHORT_DIVISOR.
   4
   5 Copyright 1991, 1993, 1994, 1996, 1998, 2001, 2002, 2004, 2012 Free Software
   6 Foundation, Inc.
   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
  11 it under the terms of either:
  12
  13   * the GNU Lesser General Public License as published by the Free
  14     Software Foundation; either version 3 of the License, or (at your
  15     option) any later version.
  16
  17 or
  18
  19   * the GNU General Public License as published by the Free Software
  20     Foundation; either version 2 of the License, or (at your option) any
  21     later version.
  22
  23 or both in parallel, as here.
  24
  25 The GNU MP Library is distributed in the hope that it will be useful, but
  26 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  27 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  28 for more details.
  29
  30 You should have received copies of the GNU General Public License and the
  31 GNU Lesser General Public License along with the GNU MP Library.  If not,
  32 see https://www.gnu.org/licenses/.  */
  33
  34 #include "gmp.h"
  35 #include "gmp-impl.h"
  36
  37 unsigned long int
  38 mpz_tdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
  39 {
  40   mp_size_t ns, nn, qn;
  41   mp_ptr np, qp;
  42   mp_limb_t rl;
  43
  44   if (UNLIKELY (divisor == 0))
  45     DIVIDE_BY_ZERO;
  46
  47   ns = SIZ(dividend);
  48   if (ns == 0)
  49     {
  50       SIZ(quot) = 0;
  51       SIZ(rem) = 0;
  52       return 0;
  53     }
  54
  55   nn = ABS(ns);
  56   qp = MPZ_REALLOC (quot, nn);
  57   np = PTR(dividend);
  58
  59 #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
  60   if (divisor > GMP_NUMB_MAX)
  61     {
  62       mp_limb_t dp[2];
  63       mp_ptr rp;
  64       mp_size_t rn;
  65
  66       if (nn == 1)              /* tdiv_qr requirements; tested above for 0 */
  67         {
  68           SIZ(quot) = 0;
  69           rl = np[0];
  70           SIZ(rem) = ns >= 0 ? 1 : -1;
  71           PTR(rem)[0] = rl;
  72           return rl;
  73         }
  74
  75       rp = MPZ_REALLOC (rem, 2);
  76
  77       dp[0] = divisor & GMP_NUMB_MASK;
  78       dp[1] = divisor >> GMP_NUMB_BITS;
  79       mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
  80       rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
  81       qn = nn - 2 + 1; qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0;
  82       rn = 2 - (rp[1] == 0);  rn -= (rp[rn - 1] == 0);
  83       SIZ(rem) = ns >= 0 ? rn : -rn;
  84     }
  85   else
  86 #endif
  87     {
  88       rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor);
  89       if (rl == 0)
  90         SIZ(rem) = 0;
  91       else
  92         {
  93           /* Store the single-limb remainder.  We don't check if there's space
  94              for just one limb, since no function ever makes zero space.  */
  95           SIZ(rem) = ns >= 0 ? 1 : -1;
  96           PTR(rem)[0] = rl;
  97         }
  98       qn = nn - (qp[nn - 1] == 0);
  99     }
 100
 101   SIZ(quot) = ns >= 0 ? qn : -qn;
 102   return rl;
 103 }