data_valid&quot; signal (this is because when the &quot;transmitter_parallel_data_valid&quot; is high (because of the transmission of the lower ALU result), the output of the NOT gate of the pulse generator is low and it won't change its value until the &quot;transmitter_parallel_data_valid&quot; becomes low. After that, the output of the NOT gate is high and a new &quot;data_valid&quot; signal can be sent). To exit &quot;WAIT_FOR_UPPER_ALU_RESULT&quot; state, the output of the pulse generator register &quo