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

   1 #include <tommath.h>
   2 #ifdef BN_MP_READ_UNSIGNED_BIN_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 /* reads a unsigned char array, assumes the msb is stored first [big endian] */
  19 int mp_read_unsigned_bin (mp_int * a, const unsigned char *b, int c)
  20 {
  21   int     res;
  22
  23   /* make sure there are at least two digits */
  24   if (a->alloc < 2) {
  25      if ((res = mp_grow(a, 2)) != MP_OKAY) {
  26         return res;
  27      }
  28   }
  29
  30   /* zero the int */
  31   mp_zero (a);
  32
  33   /* read the bytes in */
  34   while (c-- > 0) {
  35     if ((res = mp_mul_2d (a, 8, a)) != MP_OKAY) {
  36       return res;
  37     }
  38
  39 #ifndef MP_8BIT
  40       a->dp[0] |= *b++;
  41       a->used += 1;
  42 #else
  43       a->dp[0] = (*b & MP_MASK);
  44       a->dp[1] |= ((*b++ >> 7U) & 1);
  45       a->used += 2;
  46 #endif
  47   }
  48   mp_clamp (a);
  49   return MP_OKAY;
  50 }
  51 #endif
  52
  53 /* $Source: /cvs/libtom/libtommath/bn_mp_read_unsigned_bin.c,v $ */
  54 /* $Revision: 1.4 $ */
  55 /* $Date: 2006/03/31 14:18:44 $ */