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Diffstat (limited to 'tex/statemachines.tex')
| -rw-r--r-- | tex/statemachines.tex | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/tex/statemachines.tex b/tex/statemachines.tex index 9fb47e2..967737b 100644 --- a/tex/statemachines.tex +++ b/tex/statemachines.tex @@ -1,5 +1,4 @@ \section{State Machines} -There are 3 types of state machines. \begin{figure}[h] \centering \ttfamily @@ -65,21 +64,20 @@ There are 3 types of state machines. \end{figure} \subsection{Encoding the state} -This is typical for Mealey and Moore machines. +For Mealey and Moore machines it is typical to write: \begin{lstlisting}[language=vhdl] type state_type is (st_rst, st_a, st_b, st_c, ...); signal present_state, next_state : state_type; \end{lstlisting} -The encoding of the state is left automatically to the synthesizer or -configured in the graphical interface of the tool. If a custom encoding is -required (Medwedjew), adding the following generates a custom encoding. +The encoding of the state is left to the synthesizer or can be configured in +the graphical interface of the tool. If a custom encoding is required +(Medwedjew), adding the following generates a custom encoding. \begin{lstlisting}[language=vhdl] attribute enum_encoding : string; attribute enum_encoding of state_type: type is "0001 0010 0100 ..."; \end{lstlisting} - -Or alternatively a completely different approach is using a vector type. +Or an equivalent approach is to use a vector subtype and constants. \begin{lstlisting}[language=vhdl] subtype state_type is bit_vector(3 downto 0); |