Assembly-Adventure

Copyright 2022 Adina-Maria Amzarescu

The final Univeristy project for the Introduction to computer organization and assembly language course

This project has 4 tasks and 2 bonus tasks (64bit-assembly and special instruction cpuid).

---

Task 1 - Album sort

The main idea was to implement the struct node sort(int n, struct node node)** function. This function links the nodes in ascending order and returns the adress of the first node. The structure of the array should not be modified.

The structure:

struct node {
    int val;
    struct node* next;
};

Implementation:

• The function has 2 while loops
  • while1: Finds the first node and saves it, loops until there are no nodes left, contains the second while
  • while2: Sorts the nodes and links them. The sorting is done by testing the values, the linking is done by storing in [esi + ecx * 8 + 4] the adress.

---

Task 2 - Turing machine

This task has 2 separate tasks. Tests 1-5 check the first part and tests 6-10 the second part.

In this task I had to only use the stack.

• Task2 - first part

  The program finds the least common multiple. The main idea was to find the greatest common factor and then divide the a * b by it.

• Task2 - second part

  The program checks if a series of brackets are balanced. The idea was to count in ebx how many open brackets there are and in ecx how many closed brackets there are.

If the two registers store the same value, the brackets are balanced.

---

Task 3 - Word sort

Based on some given delimiters the program sorts the words using qsort. At first the sorting will be made by the number of words and if they are equal, the sorting will be made in lexicographical order.

The main 2 functions:

• void get_words(char *s, char **words, int number_of_words);

  • receives the text (string array) in which the program saves the words that need to be sorted.

• void sort(char **words, int number_of_words, int size);

  • will sort the words. size = size of a word

Aux functions:

• compare_func
  • Checks if the length of the two strings is different
  • Checks the lexicographical order of the two strings s1 and s2
• ft_strcmp
• ft_strlen

---

Task 4 - Bank accounts

The program implements more recursive functions to find how much money there is in the bank account.

The 3 recursive functions that will have a value as a parameter:

• expression(char *p, int *i) - evaluates term + term or term - term
• term(char *p, int *i) - evaluates factor * factor or factor / factor
• factor(char *p, int *i) - evaluates (expression) or number (digit array)

Details:

• p is the character array
• i is the current position
• the numbers are above 0 and whole, but after the operations they can be negative
• the divisions will be done on whole numbers
• the results are integers

---

Bonus tasks

1. Assembly 64bit

   This program interwines 2 arrays.

   Example:

   • v1 = 1 1 1 1
   • v2 = 2 2
   • interwine: 1 2 1 2 1 1

2. Special Instructions - CPUID

   CPUID is a special instruction that shows processor information. This function doesn't receive parameters, it is based on the eax register and, in some cases, ecx.

   Aux functions:

   • features It checks if vmx is avalable, if rdrand is set and if avx is set.
   • l2_cache_info Sets eax to 0x80000006 and executes cpuid and gets the cache_size.

---