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
4 Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
5 Contributed by the AriC and Caramel projects, INRIA.
6
7 This file is part of the GNU MPFR Library.
8
9 The GNU MPFR Library is free software; you can redistribute it and/or modify
10 it under the terms of the GNU Lesser General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
13
14 The GNU MPFR Library is distributed in the hope that it will be useful, but
15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17 License for more details.
18
19 You should have received a copy of the GNU Lesser General Public License
20 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
21 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
22 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23
24 #define MPFR_NEED_LONGLONG_H
25 #include "mpfr-impl.h"
26
27 int
mpfr_mul_ui(mpfr_ptr y,mpfr_srcptr x,unsigned long int u,mpfr_rnd_t rnd_mode)28 mpfr_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
mpfr_mul_si(mpfr_ptr y,mpfr_srcptr x,long int u,mpfr_rnd_t rnd_mode)121 int 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