WHILE

Conduct the conditional loop for the input.

warning

Rather than while(condition){compute} in other programming language, this unit is more similar to do{compute} while(condition)

Connection Sketch

The connection of WHILE should follow the following pattern.

The Compute Process stands for the circuit manipulating the data for each loop, such as using ALU to perform self-increasing.

note

The output signal type of Compute Process must be the same as the input signal type. Only the value can be modified.

The Condition Process stands for the circuit responsible for judging whether the loop should go on.

note

The output signal type of Condition Process must be bool.

Input Ports

There are two input ports for while loop i1 and i2.

i1 is responsibe for receiving the initial data for the loop. any type

i2 is responsible for receiving the computed data to feed back into the loop. any type

Control Port

There is one control ports c1, with type bool, responsible for controlling whether the loop should stop

Output Ports

There are three output ports for while loop o1, o2, o3.

o1 export the result data. any type.

o2 is responsibe for receiving the initial data for the loop. any type.

o3 is responsible for receiving the computed data to feed back into the loop. any type.

Function

When the signal at i1 changed, the same signal will be generated at o2 and o3 in order.

When the signal at i2 changed, the WHILE will read the bool signal at c1,

• if true, the signal from i2 will be transmitted to o2 and o3 in order.
• if false, the signal from i2 will be transmitted to o1 (export the result).

Why IN ORDER is so important

As mentioned in Timing docs, once the signal at o2 is first updated, the chain reaction will go all the way to c1. Then, o3 is updated, the chain reaction will go all the way to i2. When i2 is updated, WHILE can use the newest condition infomation at c1.

warning

It is very likely that the Trigger Unit in Initial Data circuit trigger WHILE when other Trigger Unit in Condition Process/Compute Process havn't initialized yet, so the very begining result of WHILE is very likely to be wrong. Use a Switch Sensor (Trigger Unit) with Mux at the end of Initial Data circuit and manuelly change the Switch after simulation will solve the problem.