1 /* mpfr_set_f -- set a MPFR number from a GNU MPF number
3 Copyright 1999-2015 Free Software Foundation, Inc.
4 Contributed by the AriC and Caramel 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 3 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.LESSER. If not, see
20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23 #define MPFR_NEED_LONGLONG_H
24 #include "mpfr-impl.h"
27 mpfr_set_f (mpfr_ptr y
, mpf_srcptr x
, mpfr_rnd_t rnd_mode
)
29 mp_limb_t
*my
, *mx
, *tmp
;
30 unsigned long cnt
, sx
, sy
;
31 int inexact
, carry
= 0;
32 MPFR_TMP_DECL(marker
);
34 sx
= ABS(SIZ(x
)); /* number of limbs of the mantissa of x */
36 if (sx
== 0) /* x is zero */
40 return 0; /* 0 is exact */
43 if (SIZ(x
) * MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y
)) < 0)
46 sy
= MPFR_LIMB_SIZE (y
);
50 count_leading_zeros(cnt
, mx
[sx
- 1]);
52 if (sy
<= sx
) /* we may have to round even when sy = sx */
54 unsigned long xprec
= sx
* GMP_NUMB_BITS
;
56 MPFR_TMP_MARK(marker
);
57 tmp
= MPFR_TMP_LIMBS_ALLOC (sx
);
59 mpn_lshift (tmp
, mx
, sx
, cnt
);
61 /* FIXME: we may avoid the copy here, and directly call mpfr_round_raw
62 on mx instead of tmp */
63 MPN_COPY (tmp
, mx
, sx
);
64 carry
= mpfr_round_raw (my
, tmp
, xprec
, (SIZ(x
) < 0), MPFR_PREC(y
),
66 if (MPFR_UNLIKELY(carry
)) /* result is a power of two */
67 my
[sy
- 1] = MPFR_LIMB_HIGHBIT
;
68 MPFR_TMP_FREE(marker
);
73 mpn_lshift (my
+ sy
- sx
, mx
, sx
, cnt
);
75 MPN_COPY (my
+ sy
- sx
, mx
, sx
);
76 MPN_ZERO(my
, sy
- sx
);
77 /* no rounding necessary, since y has a larger mantissa */
81 /* warning: EXP(x) * GMP_NUMB_BITS may exceed the maximal exponent */
82 if (EXP(x
) > 1 + (__gmpfr_emax
- 1) / GMP_NUMB_BITS
)
84 /* EXP(x) >= 2 + floor((__gmpfr_emax-1)/GMP_NUMB_BITS)
85 EXP(x) >= 2 + (__gmpfr_emax - GMP_NUMB_BITS) / GMP_NUMB_BITS
86 >= 1 + __gmpfr_emax / GMP_NUMB_BITS
87 EXP(x) * GMP_NUMB_BITS >= __gmpfr_emax + GMP_NUMB_BITS
88 Since 0 <= cnt <= GMP_NUMB_BITS-1, and 0 <= carry <= 1,
89 we have then EXP(x) * GMP_NUMB_BITS - cnt + carry > __gmpfr_emax */
90 return mpfr_overflow (y
, rnd_mode
, MPFR_SIGN (y
));
94 /* Do not use MPFR_SET_EXP as the exponent may be out of range. */
95 MPFR_EXP (y
) = EXP (x
) * GMP_NUMB_BITS
- (mpfr_exp_t
) cnt
+ carry
;
98 return mpfr_check_range (y
, inexact
, rnd_mode
);