
diff -r bdf84605b6cd -r 6322922aa990 coursework/cw03.tex
--- a/coursework/cw03.tex	Fri Nov 07 13:54:50 2014 +0000
+++ b/coursework/cw03.tex	Fri Nov 07 14:02:38 2014 +0000
@@ -1,69 +1,19 @@
 \documentclass{article}
-\usepackage{hyperref}
-\usepackage{amssymb}
-\usepackage{amsmath}
+\usepackage{../style}
 \usepackage{../langs}
 
-\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}%
 \begin{document}
 
 \section*{Coursework 3}
 
 \noindent
-This coursework is worth 5\% and is due on 28 November at 16:00. You are asked to 
-implement a compiler for the WHILE language that targets the
-assembler language provided by Jasmin. This assembler 
-is available from
-
-\begin{center}
-\url{http://jasmin.sourceforge.net}
-\end{center}
-
-\noindent
-There is a user guide for Jasmin
-
-\begin{center}
-\url{http://jasmin.sourceforge.net/guide.html}
-\end{center}
-
-\noindent
-and also a description of some of the instructions that the JVM understands
-
-\begin{center}
-\url{http://jasmin.sourceforge.net/instructions.html}
-\end{center}
-
-\noindent
-If you generated a correct assembler file for Jasmin, for example
-\texttt{loops.j}, you can use
-
-\begin{center}
-\texttt{java -jar jasmin-2.4/jasmin.jar loops.j}
-\end{center}
-
-\noindent
-in order to translate it to Java byte code. The resulting class file can be
-run with
-
-\begin{center}
-\texttt{java loops}
-\end{center}
-
-\noindent
-where you might need to give the correct path to the class file. There
-are also other resources about Jasmin on the Internet, for example
-\mbox{\url{http://goo.gl/Qj8TeK}} and \mbox{\url{http://goo.gl/fpVNyT}}\;.\bigskip
-
-\noindent
-You need to submit a document containing the answers for the two questions 
-below. You can do the implementation in any programming language you like, but you need 
-to submit the source code with which you answered the questions. Otherwise
-the submission will not be counted.  However, the coursework 
-will \emph{only} be judged according to the answers. You can submit your answers
-in a txt-file or as pdf.\bigskip
+This coursework is worth 5\% and is due on 28 November at 16:00. You 
+are asked to implement a parser for the WHILE language and also 
+an iterpreter.
 
 
-\subsection*{Question 1 (marked with 2\%)}
+
+\subsection*{Question 1 (marked with 1\%)}
 
 You need to lex and parse WHILE programs and submit the assembler 
 instructions for the Fibonacci program and for the program you submitted
@@ -73,246 +23,11 @@
 
 \subsection*{Question 2 (marked with 2\%)}
 
-Extend the syntax of you language so that it contains also \texttt{for}-loops, like
 
-\begin{center}
-\texttt{for} \;\textit{Id} \texttt{:=} \textit{AExp}\; \texttt{upto} \;\textit{AExp}\; \texttt{do} \textit{Block} 
-\end{center}
-
-\noindent
-The intended meaning is to first assign the variable \textit{Id} the value of the first arithmetic 
-expression, then go through the loop, at the end increase the value of the variable by 1, 
-and finally test wether the value is not less or equal to the value of the second
-arithmetic expression. For example the following instance of a \texttt{for}-loop 
-is supposed to print out the numbers \texttt{2}, \texttt{3}, \texttt{4}.
-
-
-\begin{center}
-\begin{minipage}{6cm}
-\begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]
-for i := 2 upto 4 do {
-    write i	
-}
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-There are two ways how this can be implemented: one is to adapt the code generation 
-part of the compiler and generate specific code for \texttt{for}-loops; the other is to
-translate the abstract syntax tree of \texttt{for}-loops into an abstract syntax tree using
-existing language constructs. For example the loop above could be translated
-to the following \texttt{while}-loop:
-
-\begin{center}
-\begin{minipage}{6cm}
-\begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]
-i := 2;
-while (i <= 4) do {
-    write i;
-    i := i + 1;
-}
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-In this question you are supposed to give the assembler instructions for the
-program
-
-\begin{center}
-\begin{minipage}{6cm}
-\begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]
-for i := 1 upto 10000 do {
-  for i := 1 upto 10000 do {
-  skip
-  }
-} 
-\end{lstlisting}
-\end{minipage}
-\end{center}
+\subsection*{Question 3 (marked with 2\%)}
 
 
 
-\subsection*{Further Information}
-
-The Java infrastructure unfortunately does not contain an assembler out-of-the-box
-(therefore
-you need to download the additional package Jasmin---see above). But it does contain a 
-disassembler, called \texttt{javap}. A dissembler does the ``opposite'' of an assembler: it
-generates readable assembler code from Java byte code. Have a look at the
-following example: Compile using the usual Java compiler the simple Hello World 
-program below:
-
-\begin{center}
-\begin{minipage}{10cm}
-\begin{lstlisting}[language=Java,basicstyle=\ttfamily]
-class HelloWorld {
-    public static void main(String[] args) {
-        System.out.println("Hello World!");
-    }
-}
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-You can use the command
-
-\begin{center}
-\texttt{javap -v HelloWorld}
-\end{center}
-
-\noindent
-to see the assembler instructions of the Java byte code that has been generated for this
-program. You can compare this with the code generated for the Scala
-version of Hello World.
-
-\begin{center}
-\begin{minipage}{10cm}
-\begin{lstlisting}[language=Scala,basicstyle=\ttfamily]
-object HelloWorld {
-   def main(args: Array[String]) {
-      println("Hello World!")
-  }
-}
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-
-\subsection*{Library Functions}
-
-You need to generate code for the commands \texttt{write} and \texttt{read}. This
-will require the addition of some ``library'' functions to your generated code. The first
-command even needs two versions, because you might want to write out an
-integer or a string. The Java byte code will need two separate functions for this.
-For writing out an integer, you can use the assembler code
-
-\begin{center}
-\begin{minipage}{12cm}
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-.method public static write(I)V 
-    .limit locals 5 
-    .limit stack 5 
-    iload 0 
-    getstatic java/lang/System/out Ljava/io/PrintStream; 
-    swap 
-    invokevirtual java/io/PrintStream/println(I)V 
-    return 
-.end method
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent 
-This function will invoke Java's \texttt{println} function for integers. Then if you need
-to generate code for \texttt{write x} where \texttt{x} is an integer variable, you can generate
-
-\begin{center}
-\begin{minipage}{8cm}
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-iload n 
-invokestatic XXX/XXX/write(I)V
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-where \texttt{n} is the index where the value of the variable \texttt{x} is
-stored. The \texttt{XXX/XXX} needs to be replaced with the class name 
-which you use to generate the code (for example \texttt{fib/fib} in case
-of the Fibonacci numbers).
-
-Writing out a string is similar. The corresponding library function uses strings 
-instead of integers:
-
-\begin{center}
-\begin{minipage}{12cm}
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-.method public static writes(Ljava/lang/String;)V
-   .limit stack 2
-   .limit locals 2
-   getstatic java/lang/System/out Ljava/io/PrintStream;
-   aload 0
-   invokevirtual java/io/PrintStream/println(Ljava/lang/String;)V
-   return
-.end method
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-The code that needs to be generated for \texttt{write "some\_string"} commands 
-is
-
-\begin{center}
-\begin{minipage}{8cm}
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-ldc "some_string"
-invokestatic XXX/XXX/writes(Ljava/lang/String;)V
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent
-Again you need to adjust the \texttt{XXX/XXX} part in each call.
-
-The code for \texttt{read} is more complicated. The reason is that inputting a string
-will need to be transformed into an integer. The code in Figure~\ref{read} does this.
-It can be called with
-
-\begin{center}
-\begin{minipage}{8cm}
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-invokestatic XXX/XXX/read()I 
-istore n
-\end{lstlisting}
-\end{minipage}
-\end{center}
-
-\noindent 
-where \texttt{n} is the index of the variable that requires an input.
-
-
-\begin{figure}[p]\small
-\begin{lstlisting}[basicstyle=\ttfamily, numbers=none]
-.method public static read()I 
-      .limit locals 10 
-      .limit stack 10
-
-      ldc 0 
-      istore 1  ; this will hold our final integer 
-Label1: 
-      getstatic java/lang/System/in Ljava/io/InputStream; 
-      invokevirtual java/io/InputStream/read()I 
-      istore 2 
-      iload 2 
-      ldc 10   ; the newline delimiter 
-      isub 
-      ifeq Label2 
-      iload 2 
-      ldc 32   ; the space delimiter 
-      isub 
-      ifeq Label2
-
-      iload 2 
-      ldc 48   ; we have our digit in ASCII, have to subtract it from 48 
-      isub 
-      ldc 10 
-      iload 1 
-      imul 
-      iadd 
-      istore 1 
-      goto Label1 
-Label2: 
-      ;when we come here we have our integer computed in Local Variable 1 
-      iload 1 
-      ireturn 
-.end method
-\end{lstlisting}\normalsize
-\caption{Assembler code for reading an integer from the console.\label{read}}
-\end{figure}
 
 \end{document}
 




