Identifying the purpose of a circuit from the VHDL definition file

[Weaver]

Homework Statement

Complete timing signal from VHDL and identify what the circuit is used for (see picture below)

Relevant Equations

N/A

I have attempted to sketch the timing and got the following graph

From reading the VHDL code my understanding is io each rising edge clock tick the system will carry out one of the following (choosing based on priority):

1. reset if Clear_L is high
2. load in a value if Clear_D is high
3. UP count if Up is high
4. Down count if nothing else

From this, I got this graph:

Points of interest are:

• IQ rolls over to 128 when 0-1 happens (I believe that's how unsigned works in VHDL)
• Q lags one behind IQ as with VHDL will simultaneous carry out all lexical blocks of code, meaning the check for UP will occur at the same time Q is assigned to IQ so it won't capture the changed value

But what the point of the circuit is, I am not sure. I guess it could be a for a reaction timer? But I'm really unsure. Especially as will rollover if left for too long and you can load a value in

EDIT: It would roll over to 256 not 128 in the graph as IQ is 8 bits, (I mistakenly read it as 7 bits)

 

[berkeman]

Is the vector "D" defined somewhere? Sorry if I'm missing it.