15 provided by Jasmin or Krakatau. You can do the implementation

    15 provided by Jasmin or Krakatau (both have very similar

    16 in any programming language you like, but you need to submit

    16 syntax). You can do the implementation in any programming

    17 the source code with which you answered the questions,

    17 language you like, but you need to submit the source code with

    18 otherwise a mark of 0\% will be awarded. You should use the

    18 which you answered the questions, otherwise a mark of 0\% will

    19 lexer and parser from the previous courseworks. 

    19 be awarded. You should use the lexer and parser from the

    20 previous courseworks. 

    30 \subsection*{Assemblers}

    31 \subsection*{Jasmin Assembler}

    45 \noindent

    46 \noindent and also a description of some of the instructions

    46 and also a description of some of the instructions that the JVM understands

    47 that the JVM understands

    52 \noindent

    53 \noindent If you generated a correct assembler file for

    53 If you generated a correct assembler file for Jasmin, for example

    54 Jasmin, for example \texttt{loops.j}, you can use

    54 \texttt{loops.j}, you can use

    60 \noindent

    60 \noindent in order to translate it into Java Byte Code. The

    61 in order to translate it to Java byte code. The resulting class file can be

    61 resulting class file can be run with

    62 run with

    68 \noindent

    67 \noindent where you might need to give the correct path to the

    69 where you might need to give the correct path to the class file. 

    68 class file. For example:

    70 For example:

    76 \noindent 

    74 \noindent There are also other resources about Jasmin on the

    77 There are also other resources about Jasmin on the Internet, for example

    75 Internet, for example

    78 

    76 

    79 \begin{center}

    77 \begin{center}

    80 \url{http://www.ceng.metu.edu.tr/courses/ceng444/link/f3jasmintutorial.html}

    78 \small\url{http://www.ceng.metu.edu.tr/courses/ceng444/link/f3jasmintutorial.html}

    81 

    79 \end{center}

    82 and

    80 

    83 

    81 \noindent and

    84 \url{http://www.csc.villanova.edu/~tway/courses/csc8505/s2011/handouts/JVM%20and%20Jasmin.pdf}

    82 

    85 \end{center}

    83 \begin{center}

    86 

    84 \small\url{http://www.csc.villanova.edu/~tway/courses/csc8505/s2011/handouts/JVM%20and%20Jasmin.pdf}

    87 \noindent

    85 \end{center}

    88 You need to submit a document containing the answers for the two questions 

    86 

    89 below. You can do the implementation in any programming language you like, but you need 

    87 \subsection*{Krakatau Assembler}

    90 to submit the source code with which you answered the questions. Otherwise

    88 

    91 the submission will not be counted.  However, the coursework 

    89 The Krakatau assembler is available from

    92 will \emph{only} be judged according to the answers. You can submit your answers

    90 

    93 in a txt-file or as pdf.\bigskip

    91 \begin{center}

    92 \url{https://github.com/Storyyeller/Krakatau}

    93 \end{center}

    94 

    95 \noindent This assembler requires Python and a package called

    96 \pcode{ply} available from

    97 

    98 \begin{center}

    99 \url{https://pypi.python.org/pypi/ply}

   100 \end{center}

   101 

   102 \noindent This assembler is largely compatible with the Jasmin

   103 syntax---that means for the files we look are concerned with,

   104 it understands the same input syntax (no changes to your

   105 compiler need to be made). You can generate Java Byte Code by

   106 using 

   107 

   108 \begin{center}

   109 \texttt{python Krakatau-master/assemble.py loops.j}

   110 \end{center}

   111 

   112 \noindent where you may have to adapt the directory where

   113 Krakatau is installed (I just downloaded the zip file from

   114 Github and \pcode{Krakatau-master} was the directory where it

   115 was installed).

   116 

   117 

   118 %\noindent You need to submit a document containing the answers

   119 %for the two questions below. You can do the implementation in

   120 %any programming language you like, but you need to submit the

   121 %source code with which you answered the questions. Otherwise

   122 %the submission will not be counted. However, the coursework

   123 %will \emph{only} be judged according to the answers. You can

   124 %submit your answers in a txt-file or as pdf.\bigskip

    98 You need to lex and parse WHILE programs, and then generate Java Byte

   129 You need to lex and parse WHILE programs, and then generate

    99 Code instructions for the Jasmin assembler. As solution you need to

   130 Java Byte Code instructions for the Jasmin assembler (or

   100 submit the assembler instructions for the Fibonacci and Factorial

   131 Krakatau assembler). As solution you need to submit the

   101 programs. Both should be so modified that a user can input on the

   132 assembler instructions for the Fibonacci and Factorial

   102 console which Fibonacci number and which Factorial should

   133 programs. Both should be so modified that a user can input on

   103 calculated. The Fibonacci program is given in Figure~\ref{fibs}. You

   134 the console which Fibonacci number and which Factorial should

   104 can write your own program for calculating factorials.

   135 be calculated. The Fibonacci program is given in

   136 Figure~\ref{fibs}. You can write your own program for

   137 calculating factorials.

   113 Extend the syntax of you language so that it contains also \texttt{for}-loops, like

   146 Extend the syntax of your language so that it contains also

   147 \texttt{for}-loops, like

   119 \noindent

   153 \noindent The intended meaning is to first assign the variable

   120 The intended meaning is to first assign the variable \textit{Id} the value of the first arithmetic 

   154 \textit{Id} the value of the first arithmetic expression, then

   121 expression, then go through the loop, at the end increase the value of the variable by 1, 

   155 go through the loop, at the end increase the value of the

   122 and finally test wether the value is not less or equal to the value of the second

   156 variable by 1, and finally test wether the value is not less

   123 arithmetic expression. For example the following instance of a \texttt{for}-loop 

   157 or equal to the value of the second arithmetic expression (in

   124 is supposed to print out the numbers \texttt{2}, \texttt{3}, \texttt{4}.

   158 case it is greater, you should leave the loop). For example

   125 

   159 the following instance of a \texttt{for}-loop is supposed to

   126 

   160 print out the numbers \texttt{2}, \texttt{3}, \texttt{4}.

   127 \begin{center}

   161 

   128 \begin{minipage}{6cm}

   162 

   129 \begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]

   163 \begin{center}

   164 \begin{minipage}{12cm}

   165 \begin{lstlisting}[language=While, numbers=none]

   137 \noindent

   173 \noindent There are two ways how this can be implemented: one

   138 There are two ways how this can be implemented: one is to adapt the code generation 

   174 is to adapt the code generation part of the compiler and

   139 part of the compiler and generate specific code for \texttt{for}-loops; the other is to

   175 generate specific code for \texttt{for}-loops; the other is to

   140 translate the abstract syntax tree of \texttt{for}-loops into an abstract syntax tree using

   176 translate the abstract syntax tree of \texttt{for}-loops into

   141 existing language constructs. For example the loop above could be translated

   177 an abstract syntax tree using existing language constructs.

   142 to the following \texttt{while}-loop:

   178 For example the loop above could be translated to the

   143 

   179 following \texttt{while}-loop:

   144 \begin{center}

   180 

   145 \begin{minipage}{6cm}

   181 \begin{center}

   146 \begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]

   182 \begin{minipage}{12cm}

   183 \begin{lstlisting}[language=While, numbers=none]

   158 \noindent

   195 \noindent In this question you are supposed to give the

   159 In this question you are supposed to give the assembler instructions for the

   196 assembler instructions for the program

   160 program

   197 

   161 

   198 \begin{center}

   162 \begin{center}

   199 \begin{minipage}{12cm}

   163 \begin{minipage}{6cm}

   200 \begin{lstlisting}[language=While, numbers=none]

   164 \begin{lstlisting}[language=While,basicstyle=\ttfamily, numbers=none]

   177 Explain you decision and indicate what this program would

   213 Explain your decision and indicate what this program would

   182 The Java infrastructure unfortunately does not contain an assembler out-of-the-box

   218 The Java infrastructure unfortunately does not contain an

   183 (therefore

   219 assembler out-of-the-box (therefore you need to download the

   184 you need to download the additional package Jasmin---see above). But it does contain a 

   220 additional package Jasmin or Krakatau---see above). But it

   185 disassembler, called \texttt{javap}. A dissembler does the ``opposite'' of an assembler: it

   221 does contain a disassembler, called \texttt{javap}. A

   186 generates readable assembler code from Java byte code. Have a look at the

   222 dissembler does the ``opposite'' of an assembler: it generates

   187 following example: Compile using the usual Java compiler the simple Hello World 

   223 readable assembler code from Java Byte Code. Have a look at

   188 program below:

   224 the following example: Compile using the usual Java compiler

   189 

   225 the simple Hello World program below:

   190 \begin{center}

   226 

   191 \begin{minipage}{10cm}

   227 \begin{center}

   228 \begin{minipage}{12cm}

   206 \texttt{javap -v HelloWorld}

   243 \begin{minipage}{12cm}

   207 \end{center}

   244 \begin{lstlisting}[language={},numbers=none]

   208 

   245 javap -v HelloWorld

   209 \noindent to see the assembler instructions of the Java byte

   246 \end{lstlisting}

   210 code that has been generated for this program. You can compare

   247 \end{minipage}

   248 \end{center}

   249 

   250 \noindent to see the assembler instructions of the Java Byte

   251 Code that has been generated for this program. You can compare

   215 \begin{minipage}{10cm}

   256 \begin{minipage}{12cm}

   252 \noindent 

   293 \noindent This function will invoke Java's \texttt{println}

   253 This function will invoke Java's \texttt{println} function for integers. Then if you need

   294 function for integers. Then if you need to generate code for

   254 to generate code for \texttt{write x} where \texttt{x} is an integer variable, you can generate

   295 \texttt{write x} where \texttt{x} is an integer variable, you

   255 

   296 can generate

   256 \begin{center}

   297 

   257 \begin{minipage}{8cm}

   298 \begin{center}

   299 \begin{minipage}{12cm}

   265 \noindent

   307 \noindent where \texttt{n} is the index where the value of the

   266 where \texttt{n} is the index where the value of the variable \texttt{x} is

   308 variable \texttt{x} is stored. The \texttt{XXX/XXX} needs to

   267 stored. The \texttt{XXX/XXX} needs to be replaced with the class name 

   309 be replaced with the class name which you use to generate the

   268 which you use to generate the code (for example \texttt{fib/fib} in case

   310 code (for example \texttt{fib/fib} in case of the Fibonacci

   269 of the Fibonacci numbers).

   311 numbers).

   270 

   312 

   271 Writing out a string is similar. The corresponding library function uses strings 

   313 Writing out a string is similar. The corresponding library

   272 instead of integers:

   314 function uses strings instead of integers:

   279    .limit locals 2

   321    .limit locals 1

   289 \noindent

   331 \noindent The code that needs to be generated for \code{write

   290 The code that needs to be generated for \code{write "some_string"} commands 

   332 "some_string"} commands is

   291 is

   333 

   292 

   334 \begin{center}

   293 \begin{center}

   335 \begin{minipage}{12cm}

   294 \begin{minipage}{8cm}

   302 \noindent

   343 \noindent Again you need to adjust the \texttt{XXX/XXX} part

   303 Again you need to adjust the \texttt{XXX/XXX} part in each call.

   344 in each call.

   304 

   345 

   305 The code for \texttt{read} is more complicated. The reason is that inputting a string

   346 The code for \texttt{read} is more complicated. The reason is

   306 will need to be transformed into an integer. The code in Figure~\ref{read} does this.

   347 that inputting a string will need to be transformed into an

   307 It can be called with

   348 integer. The code in Figure~\ref{read} does this. It can be

   308 

   349 called with

   309 \begin{center}

   350 

   310 \begin{minipage}{8cm}

   351 \begin{center}

   352 \begin{minipage}{12cm}