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

   1 #include <tommath.h>
   2 #ifdef BN_MP_GROW_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 /* grow as required */
  19 int mp_grow (mp_int * a, int size)
  20 {
  21   int     i;
  22   mp_digit *tmp;
  23
  24   /* if the alloc size is smaller alloc more ram */
  25   if (a->alloc < size) {
  26     /* ensure there are always at least MP_PREC digits extra on top */
  27     size += (MP_PREC * 2) - (size % MP_PREC);
  28
  29     /* reallocate the array a->dp
  30      *
  31      * We store the return in a temporary variable
  32      * in case the operation failed we don't want
  33      * to overwrite the dp member of a.
  34      */
  35     tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
  36     if (tmp == NULL) {
  37       /* reallocation failed but "a" is still valid [can be freed] */
  38       return MP_MEM;
  39     }
  40
  41     /* reallocation succeeded so set a->dp */
  42     a->dp = tmp;
  43
  44     /* zero excess digits */
  45     i        = a->alloc;
  46     a->alloc = size;
  47     for (; i < a->alloc; i++) {
  48       a->dp[i] = 0;
  49     }
  50   }
  51   return MP_OKAY;
  52 }
  53 #endif
  54
  55 /* $Source: /cvs/libtom/libtommath/bn_mp_grow.c,v $ */
  56 /* $Revision: 1.3 $ */
  57 /* $Date: 2006/03/31 14:18:44 $ */