| /* mpfr_set_q -- set a floating-point number from a multiple-precision rational |
| |
| Copyright 2000, 2001, 2002, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| Contributed by the Arenaire and Cacao projects, INRIA. |
| |
| This file is part of the GNU MPFR Library. |
| |
| The GNU MPFR Library is free software; you can redistribute it and/or modify |
| it under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or (at your |
| option) any later version. |
| |
| The GNU MPFR Library is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with the GNU MPFR Library; see the file COPYING.LIB. If not, write to |
| the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, |
| MA 02110-1301, USA. */ |
| |
| #define MPFR_NEED_LONGLONG_H |
| #include "mpfr-impl.h" |
| |
| /* |
| * Set f to z, choosing the smallest precision for f |
| * so that z = f*(2^BPML)*zs*2^(RetVal) |
| */ |
| static int |
| set_z (mpfr_ptr f, mpz_srcptr z, mp_size_t *zs) |
| { |
| mp_limb_t *p; |
| mp_size_t s; |
| int c; |
| mp_prec_t pf; |
| |
| MPFR_ASSERTD (mpz_sgn (z) != 0); |
| |
| /* Remove useless ending 0 */ |
| for (p = PTR (z), s = *zs = ABS (SIZ (z)) ; *p == 0; p++, s--) |
| MPFR_ASSERTD (s >= 0); |
| |
| /* Get working precision */ |
| count_leading_zeros (c, p[s-1]); |
| pf = s * BITS_PER_MP_LIMB - c; |
| if (pf < MPFR_PREC_MIN) |
| pf = MPFR_PREC_MIN; |
| mpfr_init2 (f, pf); |
| |
| /* Copy Mantissa */ |
| if (MPFR_LIKELY (c)) |
| mpn_lshift (MPFR_MANT (f), p, s, c); |
| else |
| MPN_COPY (MPFR_MANT (f), p, s); |
| |
| MPFR_SET_SIGN (f, mpz_sgn (z)); |
| MPFR_SET_EXP (f, 0); |
| |
| return -c; |
| } |
| |
| /* set f to the rational q */ |
| int |
| mpfr_set_q (mpfr_ptr f, mpq_srcptr q, mp_rnd_t rnd) |
| { |
| mpz_srcptr num, den; |
| mpfr_t n, d; |
| int inexact; |
| int cn, cd; |
| long shift; |
| mp_size_t sn, sd; |
| MPFR_SAVE_EXPO_DECL (expo); |
| |
| num = mpq_numref (q); |
| den = mpq_denref (q); |
| /* NAN and INF for mpq are not really documented, but could be found */ |
| if (MPFR_UNLIKELY (mpz_sgn (num) == 0)) |
| { |
| if (MPFR_UNLIKELY (mpz_sgn (den) == 0)) |
| { |
| MPFR_SET_NAN (f); |
| MPFR_RET_NAN; |
| } |
| else |
| { |
| MPFR_SET_ZERO (f); |
| MPFR_SET_POS (f); |
| MPFR_RET (0); |
| } |
| } |
| if (MPFR_UNLIKELY (mpz_sgn (den) == 0)) |
| { |
| MPFR_SET_INF (f); |
| MPFR_SET_SIGN (f, mpz_sgn (num)); |
| MPFR_RET (0); |
| } |
| |
| MPFR_SAVE_EXPO_MARK (expo); |
| |
| cn = set_z (n, num, &sn); |
| cd = set_z (d, den, &sd); |
| |
| sn -= sd; |
| if (MPFR_UNLIKELY (sn > MPFR_EMAX_MAX / BITS_PER_MP_LIMB)) |
| { |
| inexact = mpfr_overflow (f, rnd, MPFR_SIGN (f)); |
| goto end; |
| } |
| if (MPFR_UNLIKELY (sn < MPFR_EMIN_MIN / BITS_PER_MP_LIMB -1)) |
| { |
| if (rnd == GMP_RNDN) |
| rnd = GMP_RNDZ; |
| inexact = mpfr_underflow (f, rnd, MPFR_SIGN (f)); |
| goto end; |
| } |
| |
| inexact = mpfr_div (f, n, d, rnd); |
| shift = BITS_PER_MP_LIMB*sn+cn-cd; |
| MPFR_ASSERTD (shift == BITS_PER_MP_LIMB*sn+cn-cd); |
| cd = mpfr_mul_2si (f, f, shift, rnd); |
| MPFR_SAVE_EXPO_FREE (expo); |
| if (MPFR_UNLIKELY (cd != 0)) |
| inexact = cd; |
| else |
| inexact = mpfr_check_range (f, inexact, rnd); |
| end: |
| mpfr_clear (d); |
| mpfr_clear (n); |
| return inexact; |
| } |
| |
| |