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kc3-lang/libtommath/bn_mp_set_int.c

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  • Author : Tom St Denis
    Date : 2007-04-18 09:58:18
    Hash : 333aebc8
    Message : added libtommath-0.41

  • bn_mp_set_int.c
  • #include <tommath.h>
    #ifdef BN_MP_SET_INT_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, tomstdenis@gmail.com, http://libtom.org
     */
    
    /* set a 32-bit const */
    int mp_set_int (mp_int * a, unsigned long b)
    {
      int     x, res;
    
      mp_zero (a);
      
      /* set four bits at a time */
      for (x = 0; x < 8; x++) {
        /* shift the number up four bits */
        if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
          return res;
        }
    
        /* OR in the top four bits of the source */
        a->dp[0] |= (b >> 28) & 15;
    
        /* shift the source up to the next four bits */
        b <<= 4;
    
        /* ensure that digits are not clamped off */
        a->used += 1;
      }
      mp_clamp (a);
      return MP_OKAY;
    }
    #endif
    
    /* $Source$ */
    /* $Revision$ */
    /* $Date$ */