Re: gEDA-user: one hot state machines

[Mike Jarabek <mjarabek@istop.com>]

Charles Lepple wrote:

On Fri, 8 Oct 2004 13:59:14 +0000, Karel Kulhavý <clock@twibright.com> wrote:
> > either way - a one-hot state machine might end up with 2 flops (or no
> > flops) set.
>
> So that an internal schizophreny occurs?
>
> Why are there 2 flip flops in hot state machines for remembering the same
> thing? How are hot state machines special from state machines in general?

2 or more, really.

the proper term is "one-hot state machines" (not just "hot state
machines") because if you have N states, you would have N flip-flops.

It's a different way to encode the current state. The list of
advantages escapes me at the moment.
 

Typically cited reasons for encoding with one hot:

    1) Lower Fan-in on the next state logic
    2) Higher speed, when you have states that just drop skip from one to the next
    3) `pre' decoded outputs, eg. you can generate pulse and glitchless state outputs by or-ing together the outputs.

Mike

>  
> --
> - Charles Lepple

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