Sum and Counter

[mkorbel1]

Description & Motivation

A Sum and Counter component. The Sum adds up all the things input combinationally, and the Counter adds a flop (essentially). The components are super flexible and generic.

Related Issue(s)

Fix #73

Testing

Added new tests

Backwards-compatibility

Is this a breaking change that will not be backwards-compatible? If yes, how so?

No

Documentation

Does the change require any updates to documentation? If so, where? Are they included?

Yes

[desmonddak]

Looks good. I did not walk through all logic as it is hairy. I learned some things like using inject and negEdge which I hadn't used before.

One thing I didn't check is if the Counter has good defaults for the common case (single increment, wraparound?)

[mkorbel1]

if the Counter has good defaults for the common case (single increment, wraparound?)

Yes, the default is wrap-around and requires a list of interfaces. The Counter.simple constructor can just be given a clock, reset, and width (or max value) and it would be a simple increment-by-one counter. You need to provide something so width can be inferred, but beyond that I think the defaults are convenient for what most people expect.

[desmonddak]

This PR is in great shape. My biggest question is: do we need both max and min in the same Counter. If not, the interface gets way simpler and easier to understand.

[mkorbel1]

do we need both max and min in the same Counter

Yes, because we could have both incrementing and decrementing inputs, with variable amounts and enables.