release/src/router/dropbear/libtommath/bn_mp_toradix.c

   1 #include <tommath.h>
   2 #ifdef BN_MP_TORADIX_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://math.libtomcrypt.com
  16  */
  17
  18 /* stores a bignum as a ASCII string in a given radix (2..64) */
  19 int mp_toradix (mp_int * a, char *str, int radix)
  20 {
  21   int     res, digs;
  22   mp_int  t;
  23   mp_digit d;
  24   char   *_s = str;
  25
  26   /* check range of the radix */
  27   if (radix < 2 || radix > 64) {
  28     return MP_VAL;
  29   }
  30
  31   /* quick out if its zero */
  32   if (mp_iszero(a) == 1) {
  33      *str++ = '0';
  34      *str = '\0';
  35      return MP_OKAY;
  36   }
  37
  38   if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
  39     return res;
  40   }
  41
  42   /* if it is negative output a - */
  43   if (t.sign == MP_NEG) {
  44     ++_s;
  45     *str++ = '-';
  46     t.sign = MP_ZPOS;
  47   }
  48
  49   digs = 0;
  50   while (mp_iszero (&t) == 0) {
  51     if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
  52       mp_clear (&t);
  53       return res;
  54     }
  55     *str++ = mp_s_rmap[d];
  56     ++digs;
  57   }
  58
  59   /* reverse the digits of the string.  In this case _s points
  60    * to the first digit [exluding the sign] of the number]
  61    */
  62   bn_reverse ((unsigned char *)_s, digs);
  63
  64   /* append a NULL so the string is properly terminated */
  65   *str = '\0';
  66
  67   mp_clear (&t);
  68   return MP_OKAY;
  69 }
  70
  71 #endif
  72
  73 /* $Source: /cvs/libtom/libtommath/bn_mp_toradix.c,v $ */
  74 /* $Revision: 1.3 $ */
  75 /* $Date: 2006/03/31 14:18:44 $ */