CS 453 Programming Assignment #4 — MeggyJava for Buttons

Due: Thursday, March 29 (by 11:59 PM)

Introduction

This assignment is to be done with your CS 453 programming partner. In this assignment you will be writing a program that parses the PA4 subset of the MeggyJava language that includes the detection of button presses (Meggy.checkButton), the use of the delay function (Meggy.delay), the function for reading the screen pixel values (Meggy.getPixel), the while statement, the if statement, binary operators, byte casts, plus, minus, and times, and boolean expressions. See the PA4 Meggy java grammar. Notice the dangling else syntax, and the unary minus syntax.

Java, and therefore Meggy Java allows int, byte mixed type expressions for addition, subtraction, comparison, and negation. This is relevant for type checking as well as code generation.

You will

add the PA4 grammar rules to the parser,
perform syntax-directed construction of an Abstract Syntax Tree (AST),
perform type checking in a checkType visitor, and
perform code generation to AVR assembly code for all PA4 statements using AVRgen visitor.

Check out DotVisitor.java, an example visitor, as discussed in recit. Example ASTs of the provided test programs in TestCasesMeggy are here:

The Assignment

You start with downloading the PA4Empty.tar, and incorporate your PA3 lexer. You will then modify your PA3 .cup file so that instead of performing expression evaluation and code generation it generates an AST. Then, you will extend the provide visitors performing type checking and code generation.

The input files for your compiler can be any PA4 MeggyJava program. The PA4Cylon.java example you wrote for PA1 and PA4buttondot.java are possible test cases for MJPA4_groupname.jar. The output file named InputFile.java.s should be an AVR assembly program that using the provided build process will run on the MeggyJr device. Additionally, the InputFile.java.s file must be such that we can run it through the MJSIM simulator. See the Meggy Sim instructions for usage notes. As in PA3, you need to include prolog and epilog into the .s file

    # Examples of each statement type are provided.
    # Register numbers, constant values, and labels can change.
    ldi    r24,lo8(1)
    ldi    r25,hi8(0)
    ldi    r24,73
    lds    r24, Button_A

    push   r24
    pop    r24

    call   functionName

    tst    r24    
    cp     r24, r25
    breq   MJ_L6
    brne   MJ_L7
    jmp    MJ_L6
    
    LabelWithAnyName:

For more details about the instructions see the 08-MeggyJrSimple-n-AVR.txt notes.

Notice that avrF.rtl.s already has an infinite loop at the end of main so that the program will always remain running on the Meggy Jr device even if there is no while loop in the MeggyJava program.

This assignment requires the following implementation strategies be used:

An AST must be built by the parser. The parser is no longer allowed to generated code or evaluate expressions.
Unlike in PA3, all expression evaluation needs to be done with AVR code since the return value from Meggy.checkButton() is not known until runtime.
The two concrete visitors provided, CheckTypes and AVRgenVisitor, need to be extended.

For this assignment, type checking will be performed with a visitor. You will probably want a separate visitor using the ReverseDepthFirstVisitor to associate nodes in the AST to line and position numbers. This information will need to be stored in some data structure that is passed to later visitors. Your goal is to match the type error messages that are printed by the provided MJ_PA3.jar parser and type checker.

Submitting the Assignment

Make sure you test your implementation thoroughly.
Only turnin one assignment per group.
Extend your Test Cases directory with a complete set of meggy jave codes covering all syntactic constructs in the PA4 language.
Explain your file structure and compiler functionality in a README file
Create the MJPA4_groupname.tar file that contains all the source code, the .class files, your .cup and .lex files, README file, TestCases, and a subversion.txt file. We should be able to use the jar file to run your PA4 MeggyJava compiler.
- The subversion.txt file should include output from the following:
```
svn log
svn info
    
```

Submit assignment using checkin utility.

~cs453/bin/checkin PA4 MJPA4_groupname.tar

Sanity Check (procedure TA will use to grade your assignment):

    
    tar -xf MJPA4_groupname.tar
    cd PA4

    // We will also run the test cases with different arg_opts files.
    java -jar MJPA4.jar TestCase.java
    java -jar MJSIM.jar TestCase.java.s > t1
    javac TestCase.java
    java TestCase > t2
    diff t1 t2

Late Policy

Late assignments will be accepted up to 48 hours past the due date for a 10% deduction. The assignment will not be accepted past this period. Late means anything after 11:59pm on the day the assignment is due, including 12 midnight.