1/* mpz_cdiv_r_ui -- Division rounding the quotient towards +infinity.  The
2   remainder gets the opposite sign as the denominator.  In order to make it
3   always fit into the return type, the negative of the true remainder is
4   returned.
5
6Copyright 1994-1996, 2001, 2002, 2004, 2005, 2012, 2015 Free Software
7Foundation, Inc.
8
9This file is part of the GNU MP Library.
10
11The GNU MP Library is free software; you can redistribute it and/or modify
12it under the terms of either:
13
14  * the GNU Lesser General Public License as published by the Free
15    Software Foundation; either version 3 of the License, or (at your
16    option) any later version.
17
18or
19
20  * the GNU General Public License as published by the Free Software
21    Foundation; either version 2 of the License, or (at your option) any
22    later version.
23
24or both in parallel, as here.
25
26The GNU MP Library is distributed in the hope that it will be useful, but
27WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
28or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
29for more details.
30
31You should have received copies of the GNU General Public License and the
32GNU Lesser General Public License along with the GNU MP Library.  If not,
33see https://www.gnu.org/licenses/.  */
34
35#include "gmp-impl.h"
36
37unsigned long int
38mpz_cdiv_r_ui (mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
39{
40  mp_size_t ns, nn;
41  mp_ptr np;
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(rem) = 0;
51      return 0;
52    }
53
54  nn = ABS(ns);
55  np = PTR(dividend);
56#if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
57  if (divisor > GMP_NUMB_MAX)
58    {
59      mp_limb_t dp[2];
60      mp_ptr rp, qp;
61      mp_size_t rn;
62      TMP_DECL;
63
64      rp = MPZ_REALLOC (rem, 2);
65
66      if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
67	{
68	  rl = np[0];
69	  rp[0] = rl;
70	}
71      else
72	{
73	  TMP_MARK;
74	  dp[0] = divisor & GMP_NUMB_MASK;
75	  dp[1] = divisor >> GMP_NUMB_BITS;
76	  qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
77	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
78	  TMP_FREE;
79	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
80	}
81
82      if (rl != 0 && ns >= 0)
83	{
84	  rl = divisor - rl;
85	  rp[0] = rl & GMP_NUMB_MASK;
86	  rp[1] = rl >> GMP_NUMB_BITS;
87	}
88
89      rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
90      SIZ(rem) = -rn;
91    }
92  else
93#endif
94    {
95      rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
96      if (rl == 0)
97	SIZ(rem) = 0;
98      else
99	{
100	  if (ns >= 0)
101	    rl = divisor - rl;
102
103	  MPZ_NEWALLOC (rem, 1)[0] = rl;
104	  SIZ(rem) = -1;
105	}
106    }
107
108  return rl;
109}
110