xref: /dflybsd-src/contrib/mpfr/src/init2.c (revision 2786097444a0124b5d33763854de247e230c6629)

/* mpfr_init2 -- initialize a floating-point number with given precision

Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
Contributed by the AriC and Caramel 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 3 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.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include "mpfr-impl.h"

void
mpfr_init2 (mpfr_ptr x, mpfr_prec_t p)
{
  mp_size_t xsize;
  mpfr_limb_ptr tmp;

  /* Check if we can represent the number of limbs
   * associated to the maximum of mpfr_prec_t*/
  MPFR_ASSERTN( MP_SIZE_T_MAX >= (MPFR_PREC_MAX/BYTES_PER_MP_LIMB) );

  /* Check for correct GMP_NUMB_BITS and BYTES_PER_MP_LIMB */
  MPFR_ASSERTN( GMP_NUMB_BITS == BYTES_PER_MP_LIMB * CHAR_BIT
                && sizeof(mp_limb_t) == BYTES_PER_MP_LIMB );

  MPFR_ASSERTN (mp_bits_per_limb == GMP_NUMB_BITS);

  /* Check for correct EXP NAN, ZERO & INF in both mpfr.h and mpfr-impl.h */
  MPFR_ASSERTN( __MPFR_EXP_NAN  == MPFR_EXP_NAN  );
  MPFR_ASSERTN( __MPFR_EXP_ZERO == MPFR_EXP_ZERO );
  MPFR_ASSERTN( __MPFR_EXP_INF  == MPFR_EXP_INF  );

  MPFR_ASSERTN( MPFR_EMAX_MAX <= (MPFR_EXP_MAX >> 1)  );
  MPFR_ASSERTN( MPFR_EMIN_MIN >= -(MPFR_EXP_MAX >> 1) );

  /* p=1 is not allowed since the rounding to nearest even rule requires at
     least two bits of mantissa: the neighbours of 3/2 are 1*2^0 and 1*2^1,
     which both have an odd mantissa */
  MPFR_ASSERTN(p >= MPFR_PREC_MIN && p <= MPFR_PREC_MAX);

  xsize = MPFR_PREC2LIMBS (p);
  tmp   = (mpfr_limb_ptr) (*__gmp_allocate_func)(MPFR_MALLOC_SIZE(xsize));

  MPFR_PREC(x) = p;                /* Set prec */
  MPFR_EXP (x) = MPFR_EXP_INVALID; /* make sure that the exp field has a
                                      valid value in the C point of view */
  MPFR_SET_POS(x);                 /* Set a sign */
  MPFR_SET_MANT_PTR(x, tmp);       /* Set Mantissa ptr */
  MPFR_SET_ALLOC_SIZE(x, xsize);   /* Fix alloc size of Mantissa */
  MPFR_SET_NAN(x);                 /* initializes to NaN */
}

#ifdef MPFR_USE_OWN_MPFR_TMP_ALLOC
static unsigned char mpfr_stack_tab[8000000];
unsigned char *mpfr_stack = mpfr_stack_tab;
#endif