1/* mpfr_mul_ui -- multiply a floating-point number by a machine integer
2   mpfr_mul_si -- multiply a floating-point number by a machine integer
3
4Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
5Contributed by the AriC and Caramel projects, INRIA.
6
7This file is part of the GNU MPFR Library.
8
9The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LESSER.  If not, see
21http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2251 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23
24#define MPFR_NEED_LONGLONG_H
25#include "mpfr-impl.h"
26
27int
28mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mpfr_rnd_t rnd_mode)
29{
30  mp_limb_t *yp;
31  mp_size_t xn;
32  int cnt, inexact;
33  MPFR_TMP_DECL (marker);
34
35  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
36    {
37      if (MPFR_IS_NAN (x))
38        {
39          MPFR_SET_NAN (y);
40          MPFR_RET_NAN;
41        }
42      else if (MPFR_IS_INF (x))
43        {
44          if (u != 0)
45            {
46              MPFR_SET_INF (y);
47              MPFR_SET_SAME_SIGN (y, x);
48              MPFR_RET (0); /* infinity is exact */
49            }
50          else /* 0 * infinity */
51            {
52              MPFR_SET_NAN (y);
53              MPFR_RET_NAN;
54            }
55        }
56      else /* x is zero */
57        {
58          MPFR_ASSERTD (MPFR_IS_ZERO (x));
59          MPFR_SET_ZERO (y);
60          MPFR_SET_SAME_SIGN (y, x);
61          MPFR_RET (0); /* zero is exact */
62        }
63    }
64  else if (MPFR_UNLIKELY (u <= 1))
65    {
66      if (u < 1)
67        {
68          MPFR_SET_ZERO (y);
69          MPFR_SET_SAME_SIGN (y, x);
70          MPFR_RET (0); /* zero is exact */
71        }
72      else
73        return mpfr_set (y, x, rnd_mode);
74    }
75  else if (MPFR_UNLIKELY (IS_POW2 (u)))
76    return mpfr_mul_2si (y, x, MPFR_INT_CEIL_LOG2 (u), rnd_mode);
77
78  yp = MPFR_MANT (y);
79  xn = MPFR_LIMB_SIZE (x);
80
81  MPFR_ASSERTD (xn < MP_SIZE_T_MAX);
82  MPFR_TMP_MARK(marker);
83  yp = MPFR_TMP_LIMBS_ALLOC (xn + 1);
84
85  MPFR_ASSERTN (u == (mp_limb_t) u);
86  yp[xn] = mpn_mul_1 (yp, MPFR_MANT (x), xn, u);
87
88  /* x * u is stored in yp[xn], ..., yp[0] */
89
90  /* since the case u=1 was treated above, we have u >= 2, thus
91     yp[xn] >= 1 since x was msb-normalized */
92  MPFR_ASSERTD (yp[xn] != 0);
93  if (MPFR_LIKELY (MPFR_LIMB_MSB (yp[xn]) == 0))
94    {
95      count_leading_zeros (cnt, yp[xn]);
96      mpn_lshift (yp, yp, xn + 1, cnt);
97    }
98  else
99    {
100      cnt = 0;
101    }
102
103  /* now yp[xn], ..., yp[0] is msb-normalized too, and has at most
104     PREC(x) + (GMP_NUMB_BITS - cnt) non-zero bits */
105  MPFR_RNDRAW (inexact, y, yp, (mpfr_prec_t) (xn + 1) * GMP_NUMB_BITS,
106               rnd_mode, MPFR_SIGN (x), cnt -- );
107
108  MPFR_TMP_FREE (marker);
109
110  cnt = GMP_NUMB_BITS - cnt;
111  if (MPFR_UNLIKELY (__gmpfr_emax < MPFR_EMAX_MIN + cnt
112                     || MPFR_GET_EXP (x) > __gmpfr_emax - cnt))
113    return mpfr_overflow (y, rnd_mode, MPFR_SIGN(x));
114
115  MPFR_SET_EXP (y, MPFR_GET_EXP (x) + cnt);
116  MPFR_SET_SAME_SIGN (y, x);
117
118  return inexact;
119}
120
121int mpfr_mul_si (mpfr_ptr y, mpfr_srcptr x, long int u, mpfr_rnd_t rnd_mode)
122{
123  int res;
124
125  if (u >= 0)
126    res = mpfr_mul_ui (y, x, u, rnd_mode);
127  else
128    {
129      res = -mpfr_mul_ui (y, x, -u, MPFR_INVERT_RND (rnd_mode));
130      MPFR_CHANGE_SIGN (y);
131    }
132  return res;
133}
134