Semestral work KIV/FJP

Minimalistic compiler from extended PL/0 to unreal mode x86 instructions.

Prerequisities

It is designed to be run on Linux OS. If you are interested in another OS, you will need to rewrite at least compilation script (compile.sh) and execution script (run.sh) to make it work.

Execution only

• JRE 1.8+
• qemu-system-i386 (highly recommended)

For future development

• JDK 1.8+
• nasm
• objdump

Fast execution

To test it really fast, you can use this fragment of bash code:

git clone https://github.com/cervenkam/fjp.git && cd fjp && chmod +x *.sh && ./compile.sh && ./run.sh

Execution in nutshell

For compilation use compile.sh, it has two parameters, first is the filename/path to the pl0 source, second is output file (executable), for example:

./compile.sh hilbert.pl0 out.bin

This command creates the output program out.bin, which can be executed with run.sh script:

./run.sh out.bin

This command opens QEMU emulator and runs the program.

Bare HW & disclaimer

The second option to run this program is run it on bare hardware, but it runs in unreal mode which means it can potentially corrupt anything (filesystem etc.), especially when we talk about compiled program, which can contain anything. Running program on bare hardware is not recommended, should be done only by advanced user and it is on your own risk. If you still want to run it on bare HW, generated file (for instance out.bin) is actually a OS image, which can be booted, so commands like dd can be usefull.

Custom program

If you are interested in writing your own program, you may need to look at the grammar, because this PL0 has been modified a bit.

What to expect

This compiler has been writen as a semestral work by one guy. Because of lack of time, it does not have any sort of optimalization at all, which means the generated programs are slow (even slower than Java 😁). It really needs some kind of argument passing, if you look at hilbert source code, it has been solved by explicit assigning to local variables, which really reduces the readability of the source code.

Author

• Martin Červenka

Special thanks

OS kernel has been inspired by previously used kernel created by me and these two guys:

• Petr Štechmüller
• Antonín Vrba

If you are interested more in assembly, look at out previous project at FailOS.

Compiler in action

There are four testing pl0 programs in the root folder of this project. If you compile and run these programs, you get this output:

First image (program hilbert.pl0) shows hilbert curve. The program mainly aims to test compilation of recursion and nested procedures. The second image (program circle.pl0) shows generated concentric circles and tests loops. Third example (program bounce.pl0) draws bouncing object in 45 degrees. It tests correct compilation of conditions. The forth example (program fizzbuzz.pl0) (look it up if do not know fizzbuzz program) tests mainly arithmetic, and the last one (square.pl0) tests user input (user enters number - in binary - and it prints square of given input) and logical operators.