uns src_idx = ((uns)src < ARRAY_SIZE(lookup)) ? lookup[src] : 0;
uns dest_idx = ((uns)dest < ARRAY_SIZE(lookup)) ? lookup[dest] : 0;
c->convert = tab[src_idx][dest_idx];
uns src_idx = ((uns)src < ARRAY_SIZE(lookup)) ? lookup[src] : 0;
uns dest_idx = ((uns)dest < ARRAY_SIZE(lookup)) ? lookup[dest] : 0;
c->convert = tab[src_idx][dest_idx];