pb_copy.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 /* dest = src */
  15 int pb_copy(pb_poly *src, pb_poly *dest)
  16 {
  17    int err, x;
  18
  19    /* avoid trivial copies */
  20    if (src == dest) {
  21       return MP_OKAY;
  22    }
  23
  24    /* grow dest as required */
  25    if (dest->alloc < src->used) {
  26       if ((err = pb_grow(dest, src->used)) != MP_OKAY) {
  27          return err;
  28       }
  29    }
  30
  31    /* set the characteristic */
  32    if ((err = mp_copy(&(src->characteristic), &(dest->characteristic))) != MP_OKAY) {
  33       return err;
  34    }
  35
  36    /* copy digits */
  37    for (x = 0; x < src->used; x++) {
  38        if ((err = mp_copy(&(src->terms[x]), &(dest->terms[x]))) != MP_OKAY) {
  39           return err;
  40        }
  41    }
  42
  43    /* zero excess digits */
  44    for (x = src->used; x < dest->used; x++) {
  45        mp_zero(&(dest->terms[x]));
  46    }
  47    dest->used = src->used;
  48    return MP_OKAY;
  49 }
  50
  51