Stacks, Queues - LIFO, FIFO

What is this?

A project for Holberton School, this is an interpreter for Monty bytecodes files. Monty is a scripting language that is first compiled into Monty byte codes. It relies on a unique stack data structure with specific instructions to manipulate it. Monty byte codes usually have the .m extension.

Why?

This project reviewed the concepts of file input/output, linked lists, and stack data structure.

Requirements of project

• Ubuntu 14.04 LTS
• all .c files pass Betty style: betty-style.pl and betty-doc.pl
• maximum of one global variable
• no more than 5 functions per file
• prototypes of all functions are included in header file called monty.h
• all header files are include guarded
• allowed to use standard library

Compilation

The files are to be compiled this way:

$ gcc -Wall -Werror -Wextra -pedantic *.c -o monty

How to use

1. compile files
2. $ ./monty monty_byte_code_file_name.m

A few Monty bytecode files are supplied in the byecodes directory. For supported opcodes, look below.

Example of usage

$ cat bytecodes/12.m
push 1
push 2
push 3
pall
add
pall
$ ./monty bytecodes/12.m
3
2
1
5
1

Implemented opcodes

• push

  Usage: push <int> where <int> is an integer

  What it does: pushes an element to the stack.

• pall

  Usage: pall

  What it does: prints all the values on the stack, starting from the top of the stack.

• pint

  Usage: pint

  What it does: prints the value at the top of the stack followed by a new line.

• pop

  Usage: pop

  What it does: removes the top element of the stack.

• swap

  Usage: swap

  What it does: swaps the top two elements of the stack.

• add

  Usage: add

  What it does: adds the top two elements of the stack. The answer is stored in the second top element of the stack and the top element is removed so that the top element contains the result and the stack is one element shorter.

• nop

  Usage: nop

  What it does: nothing.

• sub

  Usage: sub

  What it does: subtracts the top element of the stack from the second element of the stack. The answer is stored in the second top element of the stack and the top element is removed so that the top element contains the result and the stack is one element shorter.

• div

  Usage: div

  What it does: divides the second top element of the stack by the first element of the stack. The answer is stored in the second top element of the stack and the top element is removed so that the top element contains the result and the stack is one element shorter.

• mul

  Usage: mul

  What it does: multiplies the top two elements of the stack. The answer is stored in the second top element of the stack and the top element is removed so that the top element contains the result and the stack is one element shorter.

• mod

  Usage: mod

  What it does: computes the remainder of the division of the second top element of the stack by the top element of the stack. The answer is stored in the second top element of the stack and the top element is removed so that the top element contains the result and the stack is one element shorter.

• pchar

  Usage: pchar

  What it does: prints the character at the top of the stack if it is a printable character.

• pstr

  Usage: pstr

  What it does: prints the string starting at the top of the stack.

• rotl

  Usage: rotl

  What it does: rotates the stack to the left.

• rotr

  Usage: rotr

  What it does: rotates the stack to the right.

Challenges

• breaking down the project into smaller manageable pieces, and then breaking them into even smaller pieces so that I could have functions that each only did one thing
• trying to make main function have fewer lines
• memory leaks from not freeing dynamically allocated memory

Features that I did not implement

• stack and queue opcodes that would set the format of the data to a stack (LIFO) or queue (FIFO).