if (symbol % 2 == 0)  /* if even, prev cum is ok, update cum */
		{
		current_pair = *freq_ptr;
		high_half = (unsigned char)((current_pair & HIGH_MASK) >> HIGH_SHIFT);
		high_half_weight = translate[high_half];
		cum = prev_cum + high_half_weight;
		}
	else /* if odd, update both */
		{
		current_pair = *freq_ptr;
		total_pair_weight = both_weights[current_pair];
		cum = prev_cum + total_pair_weight;
		high_half = (unsigned char)((current_pair & HIGH_MASK) >> HIGH_SHIFT);
		high_half_weight = translate[high_half];
		prev_cum += high_half_weight;
		} /* end updating */