1/* mpz_fdiv_qr_ui -- Division rounding the quotient towards -infinity.
2   The remainder gets the same sign as the denominator.
3
4Copyright 1994, 1995, 1996, 1999, 2001, 2002, 2004 Free Software Foundation,
5Inc.
6
7This file is part of the GNU MP Library.
8
9The GNU MP Library is free software; you can redistribute it and/or modify
10it under the terms of the GNU Lesser General Public License as published by
11the Free Software Foundation; either version 3 of the License, or (at your
12option) any later version.
13
14The GNU MP Library is distributed in the hope that it will be useful, but
15WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
17License for more details.
18
19You should have received a copy of the GNU Lesser General Public License
20along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
21
22#include "gmp.h"
23#include "gmp-impl.h"
24
25unsigned long int
26mpz_fdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
27{
28  mp_size_t ns, nn, qn;
29  mp_ptr np, qp;
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      SIZ(quot) = 0;
39      SIZ(rem) = 0;
40      return 0;
41    }
42
43  nn = ABS(ns);
44  MPZ_REALLOC (quot, nn);
45  qp = PTR(quot);
46  np = PTR(dividend);
47
48#if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
49  if (divisor > GMP_NUMB_MAX)
50    {
51      mp_limb_t dp[2];
52      mp_ptr rp;
53      mp_size_t rn;
54
55      MPZ_REALLOC (rem, 2);
56      rp = PTR(rem);
57
58      if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
59	{
60	  qp[0] = 0;
61	  qn = 1;		/* a white lie, fixed below */
62	  rl = np[0];
63	  rp[0] = rl;
64	}
65      else
66	{
67	  dp[0] = divisor & GMP_NUMB_MASK;
68	  dp[1] = divisor >> GMP_NUMB_BITS;
69	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
70	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
71	  qn = nn - 2 + 1;
72	}
73
74      if (rl != 0 && ns < 0)
75	{
76	  mpn_incr_u (qp, (mp_limb_t) 1);
77	  rl = divisor - rl;
78	  rp[0] = rl & GMP_NUMB_MASK;
79	  rp[1] = rl >> GMP_NUMB_BITS;
80	}
81
82      qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0;
83      rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
84      SIZ(rem) = rn;
85    }
86  else
87#endif
88    {
89      rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor);
90      if (rl == 0)
91	SIZ(rem) = 0;
92      else
93	{
94	  if (ns < 0)
95	    {
96	      mpn_incr_u (qp, (mp_limb_t) 1);
97	      rl = divisor - rl;
98	    }
99
100	  PTR(rem)[0] = rl;
101	  SIZ(rem) = rl != 0;
102	}
103      qn = nn - (qp[nn - 1] == 0);
104    }
105
106  SIZ(quot) = ns >= 0 ? qn : -qn;
107  return rl;
108}
109