1/* mpfr_init2 -- initialize a floating-point number with given precision
2
3Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
4Contributed by the AriC and Caramel projects, INRIA.
5
6This file is part of the GNU MPFR Library.
7
8The GNU MPFR Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 3 of the License, or (at your
11option) any later version.
12
13The GNU MPFR Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
20http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23#include "mpfr-impl.h"
24
25void
26mpfr_init2 (mpfr_ptr x, mpfr_prec_t p)
27{
28  mp_size_t xsize;
29  mpfr_limb_ptr tmp;
30
31  /* Check if we can represent the number of limbs
32   * associated to the maximum of mpfr_prec_t*/
33  MPFR_ASSERTN( MP_SIZE_T_MAX >= (MPFR_PREC_MAX/BYTES_PER_MP_LIMB) );
34
35  /* Check for correct GMP_NUMB_BITS and BYTES_PER_MP_LIMB */
36  MPFR_ASSERTN( GMP_NUMB_BITS == BYTES_PER_MP_LIMB * CHAR_BIT
37                && sizeof(mp_limb_t) == BYTES_PER_MP_LIMB );
38
39  MPFR_ASSERTN (mp_bits_per_limb == GMP_NUMB_BITS);
40
41  /* Check for correct EXP NAN, ZERO & INF in both mpfr.h and mpfr-impl.h */
42  MPFR_ASSERTN( __MPFR_EXP_NAN  == MPFR_EXP_NAN  );
43  MPFR_ASSERTN( __MPFR_EXP_ZERO == MPFR_EXP_ZERO );
44  MPFR_ASSERTN( __MPFR_EXP_INF  == MPFR_EXP_INF  );
45
46  MPFR_ASSERTN( MPFR_EMAX_MAX <= (MPFR_EXP_MAX >> 1)  );
47  MPFR_ASSERTN( MPFR_EMIN_MIN >= -(MPFR_EXP_MAX >> 1) );
48
49  /* p=1 is not allowed since the rounding to nearest even rule requires at
50     least two bits of mantissa: the neighbours of 3/2 are 1*2^0 and 1*2^1,
51     which both have an odd mantissa */
52  MPFR_ASSERTN(p >= MPFR_PREC_MIN && p <= MPFR_PREC_MAX);
53
54  xsize = MPFR_PREC2LIMBS (p);
55  tmp   = (mpfr_limb_ptr) (*__gmp_allocate_func)(MPFR_MALLOC_SIZE(xsize));
56
57  MPFR_PREC(x) = p;                /* Set prec */
58  MPFR_EXP (x) = MPFR_EXP_INVALID; /* make sure that the exp field has a
59                                      valid value in the C point of view */
60  MPFR_SET_POS(x);                 /* Set a sign */
61  MPFR_SET_MANT_PTR(x, tmp);       /* Set Mantissa ptr */
62  MPFR_SET_ALLOC_SIZE(x, xsize);   /* Fix alloc size of Mantissa */
63  MPFR_SET_NAN(x);                 /* initializes to NaN */
64}
65
66#ifdef MPFR_USE_OWN_MPFR_TMP_ALLOC
67static unsigned char mpfr_stack_tab[8000000];
68unsigned char *mpfr_stack = mpfr_stack_tab;
69#endif
70