# Lab 4
Name: Anuj Sharma
Roll No.: CS22B007

---

## Question 1

.data
arr: .word 1 5 10 39 5 40 3 9 6 90
base: .word 0x10000000
space: .string " "

.text
addi x3 x0 3 #x3 is s
addi x5 x0 10 #x5 is i
addi x21 x0 10 #x21 is length of array
addi x13 x0 -1
lw x20 base # x20 is base pointer
addi x4 x20 40 #x4 is pointer to array last element
loop:
    beq x5 x13 exit #i > -1
    lw x11 0(x4)
    add x11 x11 x3 #x[i] = x[i] + s
    sw x11 0(x4)
    addi x4 x4 -4
    addi x5 x5 -1
    j loop
exit:
    addi x4 x20 0
    addi x5 x0 0
    
##code complete##

loop1: #printing array
    lw x11 0(x4)
    addi a0 x11 0
    li a7 1
    ecall
    la a0 space
    li a7 4
    ecall
    addi x4 x4 4
    addi x5 x5 1
    bne x5 x21 loop1 #i > -1
    li a7 10
    ecall

---
## Question 2

.data
arr: .word 1 2 3 4 5 6 7 8 9 10
length: .word 10
base: .word 0x10000000
true: .string "true\n"
false: .string "false\n"
.text
lw x3 length #x3 is length of array
lw x20 base #x20 is base of array
addi x2 x20 0 #pointer to array
addi x5 x0 0 #number of consecutive odd
addi x9 x0 1
addi x4 x0 0 # i = 0
addi x15 x0 3
loop:
    beq x4 x3 exit1
    lw x11 0(x2)
    and x12 x11 x9 #and with 1
    bne x12 x9 if
    addi x5 x5 1
    beq x5 x15 exit2 #if no. of odd is 3
    j else
    if:
        addi x5 x0 0
    else:
        addi x4 x4 1
        addi x2 x2 4
    j loop
exit1:
    la a0 false
    li a7 4
    ecall
    li a7 10
    ecall
exit2:
    la a0 true
    li a7 4
    ecall
    li a7 10
    ecall

---

## Question 3

.data
arr: .word 1 2 3 4 5 6 7 8 9 10
n: .word 5
base: .word 0x10000000
space: .string " "
.text
lw x3 n #x3 is n value
lw x20 base #x20 is base of array
addi x2 x20 0 #pointer1 to array
addi x12 x20 0 #pointer2 to array
addi x4 x0 0 # i = 0
loop1:
    beq x4 x3 e1
    addi x4 x4 1
    addi x12 x12 4
    j loop1
e1:
    addi x4 x0 0
loop:
    beq x4 x3 exit1
    lw x11 0(x2)
    lw x13 0(x12)
    addi a0 x11 0
    li a7 1
    ecall
    la a0 space
    li a7 4
    ecall
    li a7 10
    addi a0 x13 0
    ecall
    la a0 space
    li a7 4
    ecall
    addi x4 x4 1
    addi x2 x2 4
    addi x12 x12 4
    j loop
exit1:
    li a7 10
    ecall

---

## Question 4
Selected Question link

https://leetcode.com/problems/search-insert-position/description/

.data
arr: .word 1 2 3 4 6 7 8 9 10 11
n: .word 10
target: .word 5
base: .word 0x10000000
.text
lw x3 n #x3 is length of array
lw x20 base #x20 is base of array
lw x5 target
addi x2 x20 0 #pointer to array
addi x4 x0 0 # i = 0
loop:
    beq x4 x3 exit1
    lw x11 0(x2)
    bge x11 x5 exit1
    addi x4 x4 1
    addi x2 x2 4
    j loop
exit1:
    addi a0 x4 1
    li a7 1
    ecall

---
## Question 5

# assume starting node x14 and ending node x15 initially both are equal and pointing to memory
newNode: #argument x10 and return x11
    #assume x20 cointains address to free unused memory 
    sw x0 0(x20) #initialize value to 0
    sw x10 4(x20) #initialize address to x10
    addi x11 x20 0 #return address to memory through x11
    addi x20 x20 8 #increase pointer of free memory
    jr x1 #return
    
insertNode:
    addi x10 x0 -1 #set argument as -1, assume -1 to be null
    jal x1 newNode #create new node
    sw x11 4(x15) #set address of node to next of last node
    addi x15 x11 0 #update last node
    jr x1 #return
    
traverse:
    addi x4 x14 0 #initialize x4 to starting node for traversal
    loop:
        #excess memory at x4
        
        sw x4 4(x4) #go to next address 
        beq x4 x15 exit #if node is equal to last node end loop
        j loop
    jr x1 #return

---

## Question 6

#include <unistd.h>

// Define a block structure to store information about each allocated block
struct Block{
    size_t size;
    struct Block* next;
};

// Initial heap block
static Block* heap = NULL;

// Function to allocate memory
void* malloc(size_t size) {
    if (size==0) {
        return NULL;
    }

    // Check if the heap is uninitialized
    if (heap==NULL) {
        heap=sbrk(0);
        heap->size=0;
        heap->next=NULL;
    }

    // Iterate through the linked list to find a free block
    // this is added by free function if it is called
    Block* current= heap;
    while (current->next!=NULL) {
        if (current->next->size >= size) {
            // Found a free block with sufficient size
            Block* allocatedBlock = (Block*)((char*)current->next + sizeof(Block));
            allocatedBlock->size = size;
            return (void*)allocatedBlock;
        }
        current = current->next;
    }

    // No free block found, extend the heap
    current->next=sbrk(sizeof(Block) + size);
    if (current->next== (void*)-1) {
        return NULL; // Failed to extend the heap
    }
    current->next->size=size;
    current->next->next=NULL;

    return (void*)(current->next);
}
// Function to deallocate memory
void free(void* ptr) {
    if (ptr == NULL) {
        return;//ptr is null
    }

    // get the original block address
    Block* block = (Block*)((char*)ptr - sizeof(Block));

    // aqdd the block back to the free list
    block->next = heap->next;
    heap->next = block;
}