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| -rw-r--r-- | DigME.tex | 192 | ||||
| -rw-r--r-- | build/DigME.pdf | bin | 0 -> 85428 bytes | |||
| -rw-r--r-- | tex/docmacros.sty | 7 |
3 files changed, 196 insertions, 3 deletions
@@ -2,14 +2,13 @@ % !TeX encoding = utf8 % !TeX root = DigME.tex -%% TODO: publish to CTAN -\documentclass[]{tex/hsrzf} +\documentclass[margin=small]{tex/hsrzf} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Packages -%% TODO: publish to CTAN \usepackage{tex/hsrstud} +\usepackage{tex/docmacros} %% Language configuration \usepackage{polyglossia} @@ -22,6 +21,16 @@ version={4.0}, ]{doclicense} +%% Pretty pictures +\usepackage{tikz-timing} +\usetikztiminglibrary[rising arrows]{clockarrows} + +\tikzset{ + timing/font = {\ttfamily}, + timing/xunit = 8mm, + timing/yunit = 4mm, +} + %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Metadata @@ -52,5 +61,182 @@ \pagenumbering{arabic} +\section{Design Flow} + +\section{Design constraints static timing analysis (STA)} + +\subsection{Physical constraints} + +\subsection{Timing constraints} +\begin{figure}[h] + \centering + \begin{tikztimingtable}[] + Clock & ccccccccccc\\ + \end{tikztimingtable} +\end{figure} +\[ + t_\text{input} +\] + +\section{System level VHDL} + +\subsection{Aliases} +The goal is now to build re-usable IP blocks with VHDL. For that we need to refresh some important features of the lanugage. The first of which are aliases. +\begin{lstlisting}[language=vhdl] +signal data_bus: + std_logic_vector(31 downto 0); +alias first_nibble: + std_logic_vector(0 downto 3) + is dataBus (31 downto 28); +\end{lstlisting} + +\subsection{Generics} +%% TODO: generics + +\subsection{Generators} +Another useful feature are \vhdl{generate} statement, with the syntax that allows the instantiation of multiple components. +\begin{lstlisting}[language=vhdl] +`\optionalph{label}`: for `\reqph{identifier}` in `\reqph{range}` generate + -- optional declaration part + -- begin only required if there is a declaration +`\textrm{[}`begin`\textrm{]}` + -- concurrent statements +end generate `\optionalph{label}`; +\end{lstlisting} +For example: +\begin{lstlisting}[language=vhdl] +for i in 0 to 7 generate + x(i) <= a(i) xor b(7 - i); +end generate; +\end{lstlisting} +Or in a more realistic case, with components imported from elsewhere. +\begin{lstlisting}[ + language = vhdl, + caption = { + Example of generate with a component. + \label{lst:generate-component} + }, +] +-- in architecture +bcd_to_sseg_inst_loop: +for i in 0 to nr_digits - 1 generate + bcd_to_sseg_inst: component bcd_to_sseg + port map( + clk => clk, + rst => rst, + bcd => bcd_array(i), + sseg => sseg_array(i) + ); +end generate; +\end{lstlisting} +where \vhdl{bcd_array} and \vhdl{sseg_array} are of course array types, and \vhdl{nr_digits} is a constant. + +\subsection{Functions and procedures} +Furthermore VHDL has functions that can be useful to avoid rewriting the same code. Function have multiple inputs and a signel output, are allowed to be called recursively, but cannot declare or assign signals, nor use \vhdl{wait} statements. +\begin{lstlisting}[language=vhdl] +function `\reqph{name}` (`\optionalph{list of arguments with type}`) + return `\reqph{return type}` +is + `\optionalph{declaration of variables}` +begin + -- sequential statement (but not wait) +\end{lstlisting} +An example is a parity generator: +\begin{lstlisting}[ + language = vhdl, + caption = { + An odd parity generator function. + \label{lst:pargen} + } +] +function pargen(avect: std_ulogic_vector) + return std_ulogic +is + variable po_var : std_logic; +begin + po_var := '1'; + for i in avect'range loop + if avect(i) = '1' then + po_var := not po_var; + end if; + end loop; + return po_var; +end function pargen; +\end{lstlisting} + +In testbenches it is common to see procedures. They differ for function as they can have multiple inputs and \emph{multiple output}. Because of this they in practice are usually not synthetizable. The syntax is similar to functions: +\begin{lstlisting}[language=vhdl] +procedure `\reqph{name}` (`\optionalph{list of arguments with direction}`) is + `\optionalph{declaration of variables}` +begin + -- sequential statement +end procedure `\reqph{name}`; +\end{lstlisting} +With \emph{list of arguments with direction} it is meant an expression like \vhdl{a, b : in real, w : out real}, similar to the arguments of \vhdl{port}. + +\subsection{Arrays and records} + +To efficiently use \vhdl{generate} statement, such as in listing \ref{lst:generate-component}, we ned array types. Arrays types (fields) of other types are defined with the following syntax. +\begin{lstlisting}[language=vhdl] +type `\reqph{name}` is array (`\reqph{upper limit}` downto `\reqph{lower limit}`) of `\reqph{base type}`; +\end{lstlisting} +For example to complete listing \ref{lst:generate-component}, we create 1 by 1 matrices. +\begin{lstlisting}[language = vhdl] +constant nr_digits : integer := 3; +type bcd_array_type is + array (0 to nr_digits -1) + of std_ulogic_vector(3 downto 0); +type bcd_array_type is + array (0 to nr_digits -1) + of std_ulogic_vector(6 downto 0); +\end{lstlisting} + +While all arrays elements must have the same underlying type, \emph{records} allow for different types to be combined together. +%% TODO: syntax block +For example: +\begin{lstlisting}[language = vhdl] +type memory_access is record + address : integer range 0 to address_max -1; + mem_block : integer range 0 to 3; + data : std_ulogic_vector(word_width -1 downto 0); +end record; +\end{lstlisting} + +\subsection{Packages} + +To declare your own packges, the syntax is rather easy: +\begin{lstlisting}[language = vhdl] +`\reqph{{\tt library} and / or {\tt use} statements}` +package `\reqph{name}` is + `\optionalph{declarations}` +end `\reqph{package name}`; +\end{lstlisting} +And possibly in another file the implementation is give with: +\begin{lstlisting}[language = vhdl] +package body `\reqph{name}` is + `\reqph{list of definitions}` +end `\reqph{name}`; +\end{lstlisting} + +In practice it is common to see for example a configuration package, that contains all constants for the project. For example if we were to put the function \vhdl{pargen} from listing \ref{lst:pargen} we could do: +\begin{lstlisting}[language = vhdl] +package parity_helpers is + constant nibble : integer; + constant word : integer; + function pargen(avect : std_ulogic_vector) return std_ulogic; +end package parity_helpers; + +package body parity_helpers is + -- functions + function pargen(avect: std_ulogic_vector) + return std_ulogic + is `\textrm{From listing \ref{lst:pargen}}` + end function pargen; + -- instantiation of variables + constant nibble : integer := 4; + constant word : integer := 8; +end package body parity_helpers; +\end{lstlisting} +And later use it with \vhdl{use work.parity_helpers.all}. \end{document} diff --git a/build/DigME.pdf b/build/DigME.pdf Binary files differnew file mode 100644 index 0000000..91ab0cc --- /dev/null +++ b/build/DigME.pdf diff --git a/tex/docmacros.sty b/tex/docmacros.sty new file mode 100644 index 0000000..9fc0325 --- /dev/null +++ b/tex/docmacros.sty @@ -0,0 +1,7 @@ +\NeedsTeXFormat{LaTeX2e} +\ProvidesPackage{docmacros}[2021/05/22 v0.1 Document Macros] + +\newcommand{\ph}[1]{\textrm{\textit{#1}}} +\newcommand{\reqph}[1]{\textrm{\textlangle\,\ph{#1}\,\textrangle}} +\newcommand{\optionalph}[1]{\textrm{[\,\ph{#1}\,]}} +\newcommand{\vhdl}[1]{\lstinline[language=vhdl]{#1}} |