133 lines
3.8 KiB
TeX
133 lines
3.8 KiB
TeX
\documentclass{article}
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\usepackage{avremu}
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\usepackage{listings}
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\usepackage{hyperref}
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\usepackage{filecontents}
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\usepackage{tcolorbox}
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\usepackage{ydoc}
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\def\fileversion{v0.1}
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\def\filedate{2014/10/09}
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\makeatletter
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\def\cmd#1{\cs{\expandafter\cmd@to@cs\string#1}}
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\def\cmd@to@cs#1#2{\char\number`#2\relax}
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\DeclareRobustCommand\cs[1]{\texttt{\char`\\#1}}
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\makeatother
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\begin{filecontents*}{hello-world.c}
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#include <avr/io.h>
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int
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main(void)
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{
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char *str = "Hello World!";
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char *p = str;
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while (*p) {
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UDR = *p++;
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}
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asm volatile ("break;");
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}
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\end{filecontents*}
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\title{The \texttt{avremu} Package}
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\author{Christian Dietrich\\
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\url{stettberger@dokucode.de}\\
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\url{https://gitlab.brokenpipe.de/stettberger/avremu}}
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\begin{document}
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\maketitle
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\begin{tcolorbox}
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\lstinputlisting[language=C]{hello-world.c}
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\tcblower
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\begin{lstlisting}[language=TeX]
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\avrloadc{hello-world.c}
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\avrrun
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UDR='\avrUDR' in \avrinstrcount\ instructions
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\end{lstlisting}
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\end{tcolorbox}
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\begin{tcolorbox}
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\avrloadc{hello-world.c}\avrrun
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UDR='\avrUDR' in \avrinstrcount\ instructions
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\end{tcolorbox}
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\LaTeX\ is known as a typesetting system. But the underlying \TeX\ system is a powerful macro
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processor. In fact, TeX is a Turing-complete programming language. \TeX\ can compute anything that
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is computable. Computeability is a concept from theoretical computer science. After visiting a
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theoretical computer-science course, you will know that there are things that cannot be solved by a
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machine. Never. Look out for the halting problem.
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This package does contain an \emph{CPU emulator} for the 8-bit microcontroller platform Atmel AVR, more
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precisely it implements the instruction-set architecture of the \texttt{ATmega8}.
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\begin{tcolorbox}
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\begin{lstlisting}[language=TeX]
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\avrloadc{mandelbrot.c}
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\avrrun
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\avrdrawppm{mandelbrot.ppm}
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\immediate\write18{convert mandelbrot.ppm mandelbrot.png}
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\includegraphics[width=\linewidth]{mandelbrot.png}
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\end{lstlisting}
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\tcblower
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This picture (250x250) took 44 hours to render. The source code can be found in the test-suite
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directory under mandelbrot.c.\\
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\includegraphics[width=\linewidth]{imgs/mandelbrot-250x250}
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\end{tcolorbox}
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\section{Provided Commands}
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\DescribeMacro{\avrloadihex}{\meta{filename}}
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Load an Intel HEX formatted image of the flash into the code memory of the AVR
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emulator. Additionally the state of the AVR emulator is set back to zero.
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\DescribeMacro{\avrloadc}[\meta{compiler options}]{\meta{filename}}
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Requires \verb|--shell-escape|. Compiles C source code file with \verb|avr-gcc| and the given
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compiler options. The default compiler option set is \verb|-mmcu=atmega8 -Os|. The resulting
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\texttt{.elf} file is transformed to an Intel HEX file and loaded into the code memory of the
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emulator.
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\DescribeMacro{\avrrun}
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Run the emulator until a \textbf{break} instruction occurs.
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\DescribeMacro{\avrstep}[\meta{steps}=1]
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Run the emulator for N instructions. The default is a single step. The stepping does automatically
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end, if a \textbf{break} instruction is executed.
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\DescribeMacro{\avrinstrcount}
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Expands to the number of executed instructions.
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\DescribeMacro{\avrsinglestep}
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Starts an interactive single-stepping mode, which was mainly used for implementing the emulator.
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\DescribeMacro{\usravremulibrary}{\meta{list of libraryies}}
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\subsection{Access to the Serial Console}
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If the program write to the \verb|UDR| IO register, the emulator catched those characters in an
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internal buffer.
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\DescribeMacro{\avrUDR}
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Expands to the internal UDR buffer.
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\DescribeMacro{\avrUDRclear}
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Clears the internal UDR buffer.
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\subsection{Draw Library}
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\DescribeMacro{\useavremulibrary}{avr.draw}
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See source/test-suite/mandelbrot.c for more details.
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\section{Implementation Details}
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Read the source.
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\end{document}
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%%% Local Variables:
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%%% mode: latex
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%%% TeX-master: t
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%%% End:
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