pb_submod.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_submod(pb_poly *a, pb_poly *b, pb_poly *c, pb_poly *d)
  15 {
  16    int err;
  17    pb_poly tmp;
  18
  19    if ((err = pb_init(&tmp, &(d->characteristic))) != MP_OKAY) {
  20       return err;
  21    }
  22    if ((err = pb_sub(a, b, &tmp)) != MP_OKAY) {
  23       goto __TMP;
  24    }
  25    if ((err = pb_mod(&tmp, c, d)) != MP_OKAY) {
  26       goto __TMP;
  27    }
  28
  29    err = MP_OKAY;
  30 __TMP: pb_clear(&tmp);
  31    return err;
  32 }
  33
  34
  35