text: #include <tommath.h>
  #ifdef BN_MP_READ_RADIX_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
   */
  
  /* read a string [ASCII] in a given radix */
  int mp_read_radix (mp_int * a, const char *str, int radix)
  {
    int     y, res, neg;
    char    ch;
  
    /* zero the digit bignum */
    mp_zero(a);
  
    /* make sure the radix is ok */
    if (radix < 2 || radix > 64) {
      return MP_VAL;
    }
  
    /* if the leading digit is a
     * minus set the sign to negative.
     */
    if (*str == '-') {
      ++str;
      neg = MP_NEG;
    } else {
      neg = MP_ZPOS;
    }
  
    /* set the integer to the default of zero */
    mp_zero (a);
  
    /* process each digit of the string */
    while (*str) {
      /* if the radix < 36 the conversion is case insensitive
       * this allows numbers like 1AB and 1ab to represent the same  value
       * [e.g. in hex]
       */
      ch = (char) ((radix < 36) ? toupper (*str) : *str);
      for (y = 0; y < 64; y++) {
        if (ch == mp_s_rmap[y]) {
           break;
        }
      }
  
      /* if the char was found in the map
       * and is less than the given radix add it
       * to the number, otherwise exit the loop.
       */
      if (y < radix) {
        if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
           return res;
        }
        if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
           return res;
        }
      } else {
        break;
      }
      ++str;
    }
  
    /* set the sign only if a != 0 */
    if (mp_iszero(a) != 1) {
       a->sign = neg;
    }
    return MP_OKAY;
  }
  #endif
  
  /* $Source: /cvs/libtom/libtommath/bn_mp_read_radix.c,v $ */
  /* $Revision: 1.5 $ */
  /* $Date: 2006/12/28 01:25:13 $ */
  