source/libs/gmp/gmp-src/mpz/init2.c

   1 /* mpz_init2 -- initialize mpz, with requested size in bits.
   2
   3 Copyright 2001, 2002, 2008 Free Software Foundation, Inc.
   4
   5 This file is part of the GNU MP Library.
   6
   7 The GNU MP Library is free software; you can redistribute it and/or modify
   8 it under the terms of either:
   9
  10   * the GNU Lesser General Public License as published by the Free
  11     Software Foundation; either version 3 of the License, or (at your
  12     option) any later version.
  13
  14 or
  15
  16   * the GNU General Public License as published by the Free Software
  17     Foundation; either version 2 of the License, or (at your option) any
  18     later version.
  19
  20 or both in parallel, as here.
  21
  22 The GNU MP Library is distributed in the hope that it will be useful, but
  23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 for more details.
  26
  27 You should have received copies of the GNU General Public License and the
  28 GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 see https://www.gnu.org/licenses/.  */
  30
  31 #include <stdlib.h>
  32 #include <stdio.h>
  33 #include "gmp.h"
  34 #include "gmp-impl.h"
  35
  36 void
  37 mpz_init2 (mpz_ptr x, mp_bitcnt_t bits)
  38 {
  39   mp_size_t  new_alloc;
  40
  41   bits -= (bits != 0);          /* Round down, except if 0 */
  42   new_alloc = 1 + bits / GMP_NUMB_BITS;
  43
  44   if (sizeof (unsigned long) > sizeof (int)) /* param vs _mp_size field */
  45     {
  46       if (UNLIKELY (new_alloc > INT_MAX))
  47         {
  48           fprintf (stderr, "gmp: overflow in mpz type\n");
  49           abort ();
  50         }
  51     }
  52
  53   PTR(x) = __GMP_ALLOCATE_FUNC_LIMBS (new_alloc);
  54   ALLOC(x) = new_alloc;
  55   SIZ(x) = 0;
  56
  57 #ifdef __CHECKER__
  58   /* let the low limb look initialized, for the benefit of mpz_get_ui etc */
  59   PTR(x)[0] = 0;
  60 #endif
  61 }