pb_grow.c

   1 /* LibTomPoly, Polynomial Basis Math -- Tom St Denis
   2  *
   3  * LibTomPoly is a public domain library that provides
   4  * polynomial basis arithmetic support.  It relies on
   5  * LibTomMath for large integer support.
   6  *
   7  * This library is free for all purposes without any
   8  * express guarantee that it works.
   9  *
  10  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  11  */
  12 #include <tompoly.h>
  13
  14 int pb_grow(pb_poly *a, int size)
  15 {
  16    mp_int *tmp;
  17    int x, err;
  18
  19    if (a->alloc < size) {
  20       /* pad size upwards */
  21       size += (PB_TERMS - (size % PB_TERMS));
  22
  23       /* regrow terms */
  24       tmp = realloc(a->terms, sizeof(mp_int) * size);
  25       if (tmp == NULL) {
  26          return MP_MEM;
  27       }
  28       a->terms = tmp;
  29
  30       /* zero the new stuff (prevents mp_clear from double freeing) */
  31       memset(a->terms + a->alloc, 0, (size - a->alloc) * sizeof(mp_int));
  32
  33       /* now init the terms */
  34       for (x = a->alloc; x < size; x++) {
  35           if ((err = mp_init(&(a->terms[x]))) != MP_OKAY) {
  36              return err;
  37           }
  38       }
  39
  40       /* update info */
  41       a->alloc = size;
  42    }
  43    return MP_OKAY;
  44 }
  45
  46