My Assembly Language (MAL)

Repository: https://www.gitlab.com/tronied/mal

This project was a proof of concept for an assembly language interpreter in LARF. The scope of this project was limited to the following code sample, but could be expanded further in the future.

section .data
    counter db 1
    sum     db 0

section .text
    global _start

_start:
    ; loop from 1 to 5
    loop:
        ADD [sum], [counter] ; add counter to sum
        inc byte [counter]   ; increment counter
        cmp [counter], 5     ; compare counter with 5
        jle loop             ; if counter <= 5, jump to loop

    ; exit with sum as status code
    movzx eax, byte [sum]   ; zero-extend sum to 32 bits
    int 0x80                ; call kernel

Whilst I could use existing features for the majority, there were one or two missing features I needed to make this possible. These were jump and label support which, up until then was not possible. I added new parser flags with support for this behaviour into the Parser. A pre-scan for labels is undertaken prior to execution. This allows the program to jump to that point (both forwards and backwards) without any additional effort by the developer. Jumping is disabled by default but can be enabled, along with several other properties. This is how MAL is currently configured:

setProperty(DefaultProperty.FORWARD_JUMPING, true);
setProperty(DefaultProperty.GLOBAL_SCOPE, true);
setProperty(DefaultProperty.CASE_SENSITIVE, false);
setProperty(DefaultProperty.JUMP_SUPPORT, true);

Global scope ensures that declared variables are accessible within the programme. Forward jumping has also been enabled, but this is typically not a feature of most languages. The project uses the context to store values in each operation under the associated register names.

Compiling the project

Standalone

This project uses a 3rd party tool (Shadow JAR) to ensure that the Jar can be independently run.

To compile the project run the following command in the main projects folder:

gradle clean shadowJar

Using the Languages Runner

Once the project has been built, to run the runner class type the following:

java -jar ./build/libs/mal-0.1-all.jar

You will then be presented with the following:

My Assembly Language Test Utility
=================================
[Multi-line enabled] Please add <newline> + '.' + <return> to the end of a finished expression to evaluate the result.

To run the example, we need to use a different approach to normal as the result is not returned but instead set to a register. Let's see this by running the example:

section .data
    counter db 1
    sum     db 0

section .text
    global _start

_start:
    ; loop from 1 to 5
    loop:
        ADD [sum], [counter] ; add counter to sum
        inc byte [counter]   ; increment counter
        cmp [counter], 5     ; compare counter with 5
        jle loop             ; if counter <= 5, jump to loop

    ; exit with sum as status code
    movzx eax, byte [sum]   ; zero-extend sum to 32 bits
    int 0x80                ; call kernel
.
Result: null (Type: Null, Time taken: 51ms)

Since the actual result is set to a register called eax, we can evaluate this by specifying this along with a period on a new line:

eax
.
Result: 15 (Type: Integer, Time taken: 1ms)

We get a result of 15 which is expected. If the counter is initially set to 1 and on each iteration added to sum. We get 1 + 2 + 3 + 4 + 5 as we've set the number of iterations at 5. This therefore correctly prints out 15.

To exit, simply type exit and enter.