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 #include <stdlib.h>
  14 #include <string.h>
  15
  16 int pb_grow(pb_poly *a, int size)
  17 {
  18    mp_int *tmp;
  19    int x, err;
  20
  21    if (a->alloc < size) {
  22       /* pad size upwards */
  23       size += (PB_TERMS - (size % PB_TERMS));
  24
  25       /* regrow terms */
  26       tmp = realloc(a->terms, sizeof(mp_int) * size);
  27       if (tmp == NULL) {
  28          return MP_MEM;
  29       }
  30       a->terms = tmp;
  31
  32       /* zero the new stuff (prevents mp_clear from double freeing) */
  33       memset(a->terms + a->alloc, 0, (size - a->alloc) * sizeof(mp_int));
  34
  35       /* now init the terms */
  36       for (x = a->alloc; x < size; x++) {
  37           if ((err = mp_init(&(a->terms[x]))) != MP_OKAY) {
  38              return err;
  39           }
  40       }
  41
  42       /* update info */
  43       a->alloc = size;
  44    }
  45    return MP_OKAY;
  46 }
  47
  48