mini-MIPS Project

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mini-MIPS Project

Short explanation of this project

This project is an academic project during the second year of study at ENSTA Bretagne (Brest, France).

It aims to reproduce a simple version of the MIPS architecture (therefore the name "mini-MIPS") in order to understand the functioning of a computer and its internal architecture.

It is composed of a virtual machine (VM) and an assembler. The first one is written in C and the second one in Python.

Installation

To install the project, please clone this repository in a Linux environnement. You can use the following command :
```
git clone https://github.com/LBF38/mini-MIPS-project.git
```
Then, you can go to the corresponding folder in your terminal and use the following command to compile the VM :
```
make
```
You can now use the VM and the assembler.

Usage

Assembleur

To launch the assembler, use the format :

./src/assembleur.py [folder/source.txt] [folder/destination.bin]

Note: This command is executed in the project folder, for example under Linux : ~/mini-MIPS-project$

Example :

./src/assembleur.py data/asm.txt bin/asm.bin

If you don't specify the name of the destination file, by default the assembler will write in bin/[source name].bin

Virtual Machine

To launch the VM, use the format :

./bin/vm bin/[source].bin

Example :

./bin/vm bin/asm.bin

Note: You can compile the VM files (which is in C) with the makefile using make

Demonstration

To demonstrate the use of the assembler and the VM, you can find some examples of assembly code in the data/ folder.

This files respect the semantic chosen for the basic instructions of the VM. You can find it in the file instructions.md.

A list of simple examples

Je vais vous présenter les fichiers d'exemples que vous pouvez trouver dans le dossier data/, en vous donnant une courte explication de leur fonctionnement.

In this part, I will present the files that you can find in the data/ folder, giving you a short explanation of their functioning.

asm.txt : This file contains an example of assembly code. It is used to demonstrate the use of the assembler. It allows to test the comments, the basic instructions, the labels and the empty lines.
affiche12.txt : This file contains an example of assembly code to display 12 by performing a loop of 12 iterations.
factorial.txt : This file contains an example of assembly code to display the factorial of a number. The user is asked for a value to calculate and we can thus calculate the associated factorial. We can ask for a value between 0 and 12.

For this program, the limiting factor is the stack pointer which can be too low compared to the value requested by the user. We can see to improve this by calculating a larger stack pointer value depending on the value requested by the user and the maximum available memory.

We are also limited by the representation of numbers. We cannot exceed 2^32-1 (4294967295) because we use a uint32_t to store the numbers.

fibonnaci.txt : This file contains an example of assembly code to display the Fibonacci sequence. The code will ask the user for a value and the Fibonacci sequence will be calculated depending on this value.

For this program, the limiting factor is the same as for factorial.txt: the representation of numbers will condition the maximum value available to calculate and display.

boucle.txt : This file contains an example of assembly code to launch a loop and display its index.
helloworld.txt : This file contains an example of assembly code to display "Hello World!".

Note: helloworld.txt does not work for the moment because the data of type string are not yet recognized or treated by the assembler.

instruction_test.txt : This file contains all the instructions available in my asm semantic. It allowed me to test all the functions one by one and to check their functioning, when I had implementation problems.

A better method would have been to make unit tests directly on the assembler. I would implement them if I have the time. (see #10)

Ideas

You will find here some ideas of programs to be made in assembly to test the assembler and the VM. These ideas come from the computer architecture course at ENSTA Bretagne and the ideas of the teachers.

Calculate the points of the line $y = ax + b$ from the parameters provided by the user.
Matrix calculation, matrix multiplication.
Implementation of the Bresenham algorithm to draw a line. (Bresenham algorithm)
Syracuse sequence. (Syracuse sequence)

Ressources

Link to the article "VM in C" : Register VM in C
Link to another ressource "LC-3 VM": LC-3 VM
ASCII Table

Credits

This project was made by Mathis URIEN (@LBF38), student in Design of Digital Sytems at ENSTA Bretagne.

The course and project was given by ENSTA Bretagne's professors.

Assembleur ne gère pas les données fournis via un label

La majorité de l'assembleur est fonctionnelle (pour ne pas dire la totalité). Cependant, avec le code ci-dessous qui est censé afficher "Hello World!" 5 fois, je ne sais pas comment gérer les données.

# print 5 times "Hello, world!"
    add r2 r0 nb_iter      # r2 <= @nb_iter
    load r3 r2 0            # r3 <= mem[r2 + 0]
    add r4 r0 0             # r4 <= 0
loop_for_start:
    slt r5 r4 r3            # r5 <= (r4 < r3) ? 1 : 0
    braz r5 loop_for_end    # if (r5 == 0) {PC <= loop_for_end}
    add r20 r0 my_string   # r20 <= @my_string
    scall 4                 # print string @r20 to stdout
    add r4 r4 1             # r4 <= r4 + 1
    jmp r0 loop_for_start   # PC <= @loop_for_start
loop_for_end:
    stop                    # halt the machine
nb_iter:
    5                       # data: number 5
my_string:
    "Hello, world!\n"       # data: null terminated string

Le nb_iter est bien géré. Seul le my_string n'est pas bien géré.

Ainsi, j'ai identifié deux problèmes que je réunis ici car ils sont intrinsèquement liés :

Reconnaître et stocker les données sous forme de string. (comme la partie my_string ci-dessus) => partie assembleur
Reconnaître et fournir la string lors du décodage dans la VM. => partie VM.

A fixer :

scall 4
reconnaissance des data sous forme de string
décodage des data sous forme de string
stockage au bon endroit dans la mémoire
appel via scall 4

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