void fp_zero(fp_int *a)
{
    int size;
    a->used = 0;
    a->sign = FP_ZPOS;
#if defined(ALT_ECC_SIZE) || defined(HAVE_WOLF_BIGINT)
    size = a->size;
#else
    size = FP_SIZE;
#endif
    XMEMSET(a->dp, 0, size * sizeof(fp_digit));
}
void fp_zero(fp_int *a)
{
    int size;
    a->used = 0;
    a->sign = FP_ZPOS;
#if defined(ALT_ECC_SIZE) || defined(HAVE_WOLF_BIGINT)
    size = a->size;
#else
    size = FP_SIZE;
#endif
    XMEMSET(a->dp, 0, size * sizeof(fp_digit));
}