diff options
Diffstat (limited to '')
-rw-r--r-- | tex/testbench.tex | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/tex/testbench.tex b/tex/testbench.tex index b555feb..60e654b 100644 --- a/tex/testbench.tex +++ b/tex/testbench.tex @@ -22,6 +22,7 @@ be ignored. This is much more typical and realistic, thus when unspecified, \begin{lstlisting}[language=vhdl] y <= `\reqph{expression}` after `\reqph{time}`; \end{lstlisting} +%% TODO: tikz timing diagram \subsection{Generate stimuli} Simple stimuli (signals) are generated using processes. For example a clock @@ -75,7 +76,7 @@ For loops are also available, and can be synthesised if they run over a finite range. \begin{lstlisting}[language=vhdl] `\optionalph{label}:` for `\reqph{parameter}` in `\reqph{range}` loop - -- sequentail statements + -- sequential statements end loop `\optionalph{label}`; \end{lstlisting} A concrete example: @@ -89,7 +90,7 @@ signal a, b : std_ulogic_vector(n-1 downto 0); for i in 0 to 2**n -1 loop a <= std_ulogic_vector( to_unsigned(i, n)); - for k in 0 to 2**n - 1 loop + for k in 0 to 2**n -1 loop b <= std_ulogic_vector( to_unsigned(k, n)); end loop; @@ -97,3 +98,14 @@ end loop; \end{lstlisting} \subsection{Assertions} +Assertions are used write tests to check that a signal is in the correct state. +\begin{lstlisting}[language=vhdl] +`\optionalph{label}`: assert `\reqph{condition}` report `\reqph{string}` severity `\reqph{severity}`; +\end{lstlisting} +The \vhdl{report} and \vhdl{severity} are optional but strongly advised. The +severity can take one of 4 values: \vhdl{note}, \vhdl{warning}, \vhdl{error}, +\vhdl{failure}. Simulations can be configured to stop in when an error of the +desired severity occurrs. An example: +\begin{lstlisting}[language=vhdl] +assert (tb_y = '0') report "error at vector 11" severity error; +\end{lstlisting} |