1 /* mpfr_set_q -- set a floating-point number from a multiple-precision rational
3 Copyright 2000, 2001, 2002, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
4 Contributed by the Arenaire and Cacao projects, INRIA.
6 This file is part of the GNU MPFR Library.
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or (at your
11 option) any later version.
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LIB. If not, write to
20 the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
21 MA 02110-1301, USA. */
23 #define MPFR_NEED_LONGLONG_H
24 #include "mpfr-impl.h"
27 * Set f to z, choosing the smallest precision for f
28 * so that z = f*(2^BPML)*zs*2^(RetVal)
31 set_z (mpfr_ptr f
, mpz_srcptr z
, mp_size_t
*zs
)
38 MPFR_ASSERTD (mpz_sgn (z
) != 0);
40 /* Remove useless ending 0 */
41 for (p
= PTR (z
), s
= *zs
= ABS (SIZ (z
)) ; *p
== 0; p
++, s
--)
42 MPFR_ASSERTD (s
>= 0);
44 /* Get working precision */
45 count_leading_zeros (c
, p
[s
-1]);
46 pf
= s
* BITS_PER_MP_LIMB
- c
;
47 if (pf
< MPFR_PREC_MIN
)
53 mpn_lshift (MPFR_MANT (f
), p
, s
, c
);
55 MPN_COPY (MPFR_MANT (f
), p
, s
);
57 MPFR_SET_SIGN (f
, mpz_sgn (z
));
63 /* set f to the rational q */
65 mpfr_set_q (mpfr_ptr f
, mpq_srcptr q
, mp_rnd_t rnd
)
73 MPFR_SAVE_EXPO_DECL (expo
);
77 /* NAN and INF for mpq are not really documented, but could be found */
78 if (MPFR_UNLIKELY (mpz_sgn (num
) == 0))
80 if (MPFR_UNLIKELY (mpz_sgn (den
) == 0))
92 if (MPFR_UNLIKELY (mpz_sgn (den
) == 0))
95 MPFR_SET_SIGN (f
, mpz_sgn (num
));
99 MPFR_SAVE_EXPO_MARK (expo
);
101 cn
= set_z (n
, num
, &sn
);
102 cd
= set_z (d
, den
, &sd
);
105 if (MPFR_UNLIKELY (sn
> MPFR_EMAX_MAX
/ BITS_PER_MP_LIMB
))
107 inexact
= mpfr_overflow (f
, rnd
, MPFR_SIGN (f
));
110 if (MPFR_UNLIKELY (sn
< MPFR_EMIN_MIN
/ BITS_PER_MP_LIMB
-1))
114 inexact
= mpfr_underflow (f
, rnd
, MPFR_SIGN (f
));
118 inexact
= mpfr_div (f
, n
, d
, rnd
);
119 shift
= BITS_PER_MP_LIMB
*sn
+cn
-cd
;
120 MPFR_ASSERTD (shift
== BITS_PER_MP_LIMB
*sn
+cn
-cd
);
121 cd
= mpfr_mul_2si (f
, f
, shift
, rnd
);
122 MPFR_SAVE_EXPO_FREE (expo
);
123 if (MPFR_UNLIKELY (cd
!= 0))
126 inexact
= mpfr_check_range (f
, inexact
, rnd
);