.data;
fibonacci_seq:  .space 400   // Array of integers to hold Fibonacci sequence values

format_input:   .asciz "Enter a Fibonacci index: "       // Formatted string for user input prompt
format_entered: .asciz "Entered Fibonacci index: %d\n"   // Formatted string for showing the user entered index
format_value:   .asciz "Fibonacci value: %d\n"            // Formatted string for showing the Fibonacci value
format_sequence:.asciz "Fibonacci sequence up to index %d:\n"   // Formatted string for showing the Fibonacci sequence
format_scan:    .asciz "%d"                              // Formatted string for scanning user input
format_string: .asciz "Fibonacci sequence value at index %d: %d\n"
fib_index:      .word 0   // Integer variable to hold user entered Fibonacci index
fibonacci_seq:  .space 400   // Allocate space for the integer array

/*
 * Code segment
 */
			.text					//Define the code segment using assembler directive
			.global main			//Define the name of the function global using assembler directive



main:		str lr, [sp, #-16]!		//Save the return address onto stack and adjust the stack pointer
			ldr x0, =str0			//Load the address of 'str' into x0
			bl printf				//Call 'printf' function to print 'str' content
			ldr x0 =str1			
			ldr x1, =n				//Initialize ARM regigeter x0 with the address of correct format string
			bl scanf				//Call printf() function to ask user to enter a Fibonacci Index
			ldr x0, =str2
			ldr x1, =n
			bl printf
			 // Initialize ARM register x0 with the address of the format_input string
    ldr x0, =format_input
    // Initialize ARM register x1 with the address of integer variable fib_index
    ldr x1, =fib_index
    
    // Call scanf() function to take user input (fibonacci index)
    bl scanf

    // Initialize ARM register x0 with the address of the format_entered string
    ldr x0, =format_entered
    // Initialize ARM register x2 with the address of integer variable fib_index
    ldr x2, =fib_index
    // Initialize ARM register x1 with the value of integer variable fib_index
    ldr w1, [x2]
    // Call printf() function to show user entered Fibonacci Index
    bl printf

    // Initialize ARM register x1 with the address of integer variable fib_index
    ldr x1, =fib_index
    // Initialize ARM register x0 with the value of integer variable fib_index
    ldr w0, [x1]
    // Call fibonacci_dynamic() function to get the fibonacci Value of user entered index using dynamic programming technique
    bl fibonacci_dynamic

    // Copy the return value of fibonacci_dynamic() function from ARM x0 register to x2 register
    // in order to pass it as the third parameter to next printf() function call.
    mov x2, x0
    // Initialize ARM register x0 with the address of the format_value string
    ldr x0, =format_value
    // Call printf() function to show the fibonacci value of the user entered Index
    bl printf

    // Initialize ARM register x1 with the address of integer variable fib_index
    ldr x1, =fib_index
    // Initialize ARM register w0 with the value of integer variable fib_index
    ldr w0, [x1]
    // Call fibonacci_recursive function to get the fibonacci value of user entered index using recursive function call technique.
    bl fibonacci_recursive

    // Copy the return value of fibonacci_recursive() function from ARM x0 register to x2 register
    // in order to pass it as the third parameter to next printf() function call.
    mov x2, x0
    // Initialize ARM register x0 with the address of the format_value string
    ldr x0, =format_value
    // Call printf() function to show the fibonacci value of the user entered Index
    bl printf


    // Initialize ARM register x0 with the address of the integer array fibonacci_seq
    ldr x0, =fibonacci_seq
    
    // Initialize ARM register x2 with the address of integer variable fib_index
    ldr x2, =fib_index
    
    // Initialize ARM register w1 with the value of integer variable fib_index
    ldr w1, [x2]
    
    // Call fibonacci_sequence() function to get the sequence of fibonacci values for all indices starting from 0 and ending at user entered index
    bl fibonacci_sequence

    // Initialize ARM register x0 with the address of the format_sequence string
    ldr x0, =format_sequence
    
    // Call printf() function to print a header before showing the fibonacci sequence values from the array
    bl printf


    // Initialize ARM register x0 with the address of the integer array fibonacci_seq
    ldr x0, =fibonacci_seq
    
    // Initialize ARM register x2 with the address of integer variable fib_index
    ldr x2, =fib_index
    
    // Initialize ARM register w1 with the value of integer variable fib_index
    ldr w1, [x2]
    
    // Call show_fibonacci_seq() function to show the sequence of fibonacci values for all indices starting from 0 and ending at user entered index
    bl show_fibonacci_seq

		mov x0, xzr				//Assign zero to x0 in order to return zero from the function
		ldr lr, [sp], #16		//Adjust the stack pointer before returning from the function
		ret lr					//Return from the function





fibonacci_sequence:
    str lr, [sp, #-4]!   // Save the return address onto stack

    mov w8, w1           // Move max_index value from x1 to w8
    cbz w8, done         // Branch to 'done' if max_index is equal to zero
    
    cmp w8, #1           // Compare max_index value with 1
    beq one              // Branch to 'one' if max_index is equal to one
    
    mov w9, #1           // Use w9 as the loop counter and initialize it to 1
    mov w2, #0           // Use w2 to keep track of fib[n-2], initialize it to 0
    str w2, [x0], #4     // Place w2 value (0) at position 0 of the array
    mov w1, #1           // Use w1 to keep track of fib[n-1], initialize it to 1
    str w1, [x0], #4     // Place w1 value (1) at position 1 of the array

loop:
    cmp w9, w8           // Compare loop counter with max_index value
    beq done             // Branch to 'done' if they are equal
    
    add w3, w1, w2       // Compute fib[n] = fib[n-1] + fib[n-2]
    mov w2, w1           // Move fib[n-1] to fib[n-2]
    mov w1, w3           // Move fib[n] to fib[n-1]
    str w3, [x0], #4     // Place fib[n] at the appropriate position in the array
    
    add w9, w9, #1       // Increment the loop counter
    b loop               // Branch to the beginning of the loop

one:
    str w1, [x0], #4     // Place the value 1 at position 1 of the array
    b done               // Branch to 'done'

done:
    ldr lr, [sp], #4     // Retrieve the return address from the stack
    ret                  // Return from the function


show_fibonacci_seq:

    // Save the return address onto the stack
    str lr, [sp, #-4]!

    // Copy the array address (x0) to x3
    mov x3, x0

    // Copy the max index (x1) to x4
    mov x4, x1

    // Use x1 as the loop counter and initialize it to zero
    mov x1, #0

loop_start:
    // Compare loop counter value (x1) with the max index (x4)
    cmp x1, x4
    
    // Branch to the end of the function if they are equal
    beq end_func
    
    // Assign the address of the formatted string to x0
    ldr x0, =format_string
    
    // Assign x2 the fibonacci sequence value pointed by index x1 from the array
    ldr x2, [x3, x1, lsl #2]
    
    // Save the current index value (x1) onto the stack before calling printf
    str x1, [sp, #-8]!
    
    // Save the address of the fibonacci sequence array (x3) onto the stack before calling printf
    str x3, [sp, #-8]!
    
    // Save fibonacci sequence array max index (x4) onto stack before calling printf
    str x4, [sp, #-8]!
    
    // Call printf() function
    bl printf
    
    // Retrieve fibonacci sequence array index limit from the stack into x4
    ldr x4, [sp], #8
    
    // Retrieve the address of fibonacci sequence array from the stack into x3
    ldr x3, [sp], #8
    
    // Retrieve current loop counter value from the stack into x1
    ldr x1, [sp], #8
    
    // Increment the loop counter
    add x1, x1, #1
    
    // Branch to the beginning of the loop
    b loop_start

end_func:
    // Retrieve the return address from the stack
    ldr lr, [sp], #4
    
    // Return from the function
    ret