Question

The Fibonacci Sequence is a series of integers. The first two numbers in the sequence are both 1; after that, each number is the sum of the preceding two numbers.

1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...

For example, 1+1=2, 1+2=3, 2+3=5, 3+5=8, etc.

The nth Fibonacci number is the nth number in this sequence, so for example fibonacci(1)=1, fibonacci(2)=1, fibonacci(3)=2, fibonacci(4)=3, etc. Do not use zero-based counting; fibonacci(4)is 3, not 5.

Your assignment is to write an ARM assembler code (Fibonacci.s) that prompts the user for the nth term of the fibonacci sequence. The program will then calculate the users selected nth fibonacci term and print it out.

The program should produce this input:

Enter the desired Fibonacci term: 6
The 6th Fibonacci number is: 8

Answer 1

Please find the ARM code for finding the desired term in Fibonnaci Sequence

.LC0:

        .ascii  "Enter the desired Fibonacci term: \000"

.LC1:

        .ascii  "%d\000"

.LC2:

        .ascii  "Fibonacci of negative number is not possible.\000"

.LC3:

        .ascii  "The %d of Fibonacci is %d\012\000"

main:

        push    {fp, lr}

        add     fp, sp, #4

        sub     sp, sp, #8

        ldr     r0, .L5

        bl      printf

        sub     r3, fp, #12

        mov     r1, r3

        ldr     r0, .L5+4

        bl      __isoc99_scanf

        ldr     r3, [fp, #-12]

        cmp     r3, #0

        bge     .L2

        ldr     r0, .L5+8

        bl      puts

        b       .L3

.L2:

        ldr     r3, [fp, #-12]

        mov     r0, r3

        bl      fibonacci

        str     r0, [fp, #-8]

        ldr     r3, [fp, #-12]

        ldr     r2, [fp, #-8]

        mov     r1, r3

        ldr     r0, .L5+12

        bl      printf

.L3:

        mov     r3, #0

        mov     r0, r3

        sub     sp, fp, #4

        pop     {fp, lr}

        bx      lr

.L5:

        .word   .LC0

        .word   .LC1

        .word   .LC2

        .word   .LC3

fibonacci:

        push    {r4, fp, lr}

        add     fp, sp, #8

        sub     sp, sp, #12

        str     r0, [fp, #-16]

        ldr     r3, [fp, #-16]

        cmp     r3, #0

        bne     .L8

        mov     r3, #0

        b       .L9

.L8:

        ldr     r3, [fp, #-16]

        cmp     r3, #1

        bne     .L10

        mov     r3, #1

        b       .L9

.L10:

        ldr     r3, [fp, #-16]

        sub     r3, r3, #1

        mov     r0, r3

        bl      fibonacci

        mov     r4, r0

        ldr     r3, [fp, #-16]

        sub     r3, r3, #2

        mov     r0, r3

        bl      fibonacci

        mov     r3, r0

        add     r3, r4, r3

.L9:

        mov     r0, r3

        sub     sp, fp, #8

        pop     {r4, fp, lr}

        bx      lr