chromium / native_client / nacl-gcc / f80d6b9ee7f94755c697ffb7194fb01dd0c537dd / . / mpfr-2.4.1 / set_q.c

/* 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; | |

} | |