kc3-lang/libtommath/bn_mp_count_bits.c

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• Hash : 079b0f65
  Author :
  Date : 2015-10-30T17:55:29
  

  Getting ready for v0.43.0 release Also updated my email address... Signed-off-by: Tom St Denis <tstdenis82@gmail.com>

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• bn_mp_count_bits.c

• #include <tommath.h>
  #ifdef BN_MP_COUNT_BITS_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis
   *
   * LibTomMath is a library that provides multiple-precision
   * integer arithmetic as well as number theoretic functionality.
   *
   * The library was designed directly after the MPI library by
   * Michael Fromberger but has been written from scratch with
   * additional optimizations in place.
   *
   * The library is free for all purposes without any express
   * guarantee it works.
   *
   * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
   */
  
  /* returns the number of bits in an int */
  int
  mp_count_bits (mp_int * a)
  {
    int     r;
    mp_digit q;
  
    /* shortcut */
    if (a->used == 0) {
      return 0;
    }
  
    /* get number of digits and add that */
    r = (a->used - 1) * DIGIT_BIT;
    
    /* take the last digit and count the bits in it */
    q = a->dp[a->used - 1];
    while (q > ((mp_digit) 0)) {
      ++r;
      q >>= ((mp_digit) 1);
    }
    return r;
  }
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  

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