github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/rand/randbui.c (about)

     1  /* gmp_urandomb_ui -- random bits returned in a ulong.
     2  
     3  Copyright 2003, 2004 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 "gmp.h"
    32  #include "gmp-impl.h"
    33  
    34  
    35  /* Currently bits>=BITS_PER_ULONG is quietly truncated to BITS_PER_ULONG,
    36     maybe this should raise an exception or something.  */
    37  
    38  unsigned long
    39  gmp_urandomb_ui (gmp_randstate_ptr rstate, unsigned long bits)
    40  {
    41    mp_limb_t  a[LIMBS_PER_ULONG];
    42  
    43    /* start with zeros, since if bits==0 then _gmp_rand will store nothing at
    44       all, or if bits <= GMP_NUMB_BITS then it will store only a[0] */
    45    a[0] = 0;
    46  #if LIMBS_PER_ULONG > 1
    47    a[1] = 0;
    48  #endif
    49  
    50    _gmp_rand (a, rstate, MIN (bits, BITS_PER_ULONG));
    51  
    52  #if LIMBS_PER_ULONG == 1
    53    return a[0];
    54  #else
    55    return a[0] | (a[1] << GMP_NUMB_BITS);
    56  #endif
    57  }