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

   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@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 $ */