Line data    Source code

       1             : #include <tommath.h>
       2             : #ifdef BN_MP_RADIX_SIZE_C
       3             : /* LibTomMath, multiple-precision integer library -- Tom St Denis
       4             :  *
       5             :  * LibTomMath is a library that provides multiple-precision
       6             :  * integer arithmetic as well as number theoretic functionality.
       7             :  *
       8             :  * The library was designed directly after the MPI library by
       9             :  * Michael Fromberger but has been written from scratch with
      10             :  * additional optimizations in place.
      11             :  *
      12             :  * The library is free for all purposes without any express
      13             :  * guarantee it works.
      14             :  *
      15             :  * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
      16             :  */
      17             : 
      18             : /* returns size of ASCII reprensentation */
      19           0 : int mp_radix_size (mp_int * a, int radix, int *size)
      20             : {
      21             :   int     res, digs;
      22             :   mp_int  t;
      23             :   mp_digit d;
      24             : 
      25           0 :   *size = 0;
      26             : 
      27             :   /* special case for binary */
      28           0 :   if (radix == 2) {
      29           0 :     *size = mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1;
      30           0 :     return MP_OKAY;
      31             :   }
      32             : 
      33             :   /* make sure the radix is in range */
      34           0 :   if (radix < 2 || radix > 64) {
      35           0 :     return MP_VAL;
      36             :   }
      37             : 
      38           0 :   if (mp_iszero(a) == MP_YES) {
      39           0 :     *size = 2;
      40           0 :     return MP_OKAY;
      41             :   }
      42             : 
      43             :   /* digs is the digit count */
      44           0 :   digs = 0;
      45             : 
      46             :   /* if it's negative add one for the sign */
      47           0 :   if (a->sign == MP_NEG) {
      48           0 :     ++digs;
      49             :   }
      50             : 
      51             :   /* init a copy of the input */
      52           0 :   if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
      53           0 :     return res;
      54             :   }
      55             : 
      56             :   /* force temp to positive */
      57           0 :   t.sign = MP_ZPOS;
      58             : 
      59             :   /* fetch out all of the digits */
      60           0 :   while (mp_iszero (&t) == MP_NO) {
      61           0 :     if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
      62           0 :       mp_clear (&t);
      63           0 :       return res;
      64             :     }
      65           0 :     ++digs;
      66             :   }
      67           0 :   mp_clear (&t);
      68             : 
      69             :   /* return digs + 1, the 1 is for the NULL byte that would be required. */
      70           0 :   *size = digs + 1;
      71           0 :   return MP_OKAY;
      72             : }
      73             : 
      74             : #endif
      75             : 
      76             : /* $Source: /cvs/libtom/libtommath/bn_mp_radix_size.c,v $ */
      77             : /* $Revision: 1.5 $ */
      78             : /* $Date: 2006/12/28 01:25:13 $ */