crypto/external/bsd/heimdal/dist/lib/hcrypto/libtommath/bn_mp_fread.c

   1 /*      $NetBSD: bn_mp_fread.c,v 1.1.1.2 2014/04/24 12:45:31 pettai Exp $       */
   2
   3 #include <tommath.h>
   4 #ifdef BN_MP_FREAD_C
   5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
   6  *
   7  * LibTomMath is a library that provides multiple-precision
   8  * integer arithmetic as well as number theoretic functionality.
   9  *
  10  * The library was designed directly after the MPI library by
  11  * Michael Fromberger but has been written from scratch with
  12  * additional optimizations in place.
  13  *
  14  * The library is free for all purposes without any express
  15  * guarantee it works.
  16  *
  17  * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
  18  */
  19
  20 /* read a bigint from a file stream in ASCII */
  21 int mp_fread(mp_int *a, int radix, FILE *stream)
  22 {
  23    int err, ch, neg, y;
  24
  25    /* clear a */
  26    mp_zero(a);
  27
  28    /* if first digit is - then set negative */
  29    ch = fgetc(stream);
  30    if (ch == '-') {
  31       neg = MP_NEG;
  32       ch = fgetc(stream);
  33    } else {
  34       neg = MP_ZPOS;
  35    }
  36
  37    for (;;) {
  38       /* find y in the radix map */
  39       for (y = 0; y < radix; y++) {
  40           if (mp_s_rmap[y] == ch) {
  41              break;
  42           }
  43       }
  44       if (y == radix) {
  45          break;
  46       }
  47
  48       /* shift up and add */
  49       if ((err = mp_mul_d(a, radix, a)) != MP_OKAY) {
  50          return err;
  51       }
  52       if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
  53          return err;
  54       }
  55
  56       ch = fgetc(stream);
  57    }
  58    if (mp_cmp_d(a, 0) != MP_EQ) {
  59       a->sign = neg;
  60    }
  61
  62    return MP_OKAY;
  63 }
  64
  65 #endif
  66
  67 /* Source: /cvs/libtom/libtommath/bn_mp_fread.c,v  */
  68 /* Revision: 1.4  */
  69 /* Date: 2006/12/28 01:25:13  */