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      1 #include <tommath.h>
      2 #ifdef BN_MP_FREAD_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 (at) gmail.com, http://math.libtomcrypt.com
     16  */
     17 
     18 /* read a bigint from a file stream in ASCII */
     19 int mp_fread(mp_int *a, int radix, FILE *stream)
     20 {
     21    int err, ch, neg, y;
     22 
     23    /* clear a */
     24    mp_zero(a);
     25 
     26    /* if first digit is - then set negative */
     27    ch = fgetc(stream);
     28    if (ch == '-') {
     29       neg = MP_NEG;
     30       ch = fgetc(stream);
     31    } else {
     32       neg = MP_ZPOS;
     33    }
     34 
     35    for (;;) {
     36       /* find y in the radix map */
     37       for (y = 0; y < radix; y++) {
     38           if (mp_s_rmap[y] == ch) {
     39              break;
     40           }
     41       }
     42       if (y == radix) {
     43          break;
     44       }
     45 
     46       /* shift up and add */
     47       if ((err = mp_mul_d(a, radix, a)) != MP_OKAY) {
     48          return err;
     49       }
     50       if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
     51          return err;
     52       }
     53 
     54       ch = fgetc(stream);
     55    }
     56    if (mp_cmp_d(a, 0) != MP_EQ) {
     57       a->sign = neg;
     58    }
     59 
     60    return MP_OKAY;
     61 }
     62 
     63 #endif
     64 
     65 /* $Source: /cvs/libtom/libtommath/bn_mp_fread.c,v $ */
     66 /* $Revision: 1.3 $ */
     67 /* $Date: 2006/03/31 14:18:44 $ */
     68