$$rfib Write a recursive function in MIPS that takes one integer argument and returns the Fibonacci number corresponding to that argument:

rfib$(0)=0$

rfib $(1)$

$=1$

rfib $(2)$

$1$

rfib$(3)=2$

rfib $(4)=3$

and so on$.$

Your code should handle non$-$negative integer argument values, including zero. No need to error check for negative arguments. The function should adhere to all calling conventions, so the argument will be passed to rfib in $a$0$ and should be returned from rfib in $v$.$

$1$lsum$()$ Write a recursive function to sum the cells in a linked list. The linked list sum function takes one argument, a pointer to the first cell in a linked list, and should return the sum of all of the cells in the list.

The list resides in memory, and each cell is $8$B in size. The first $4$B is an integer containing the value of the cell. The second $4$B is a pointer to the next cell in the linked list. The last cell in the list has a null

next pointer $($i$.$e$.,$ next pointer $=0).$ Cell values may be positive or negative.

$$bubble$()$ Write a function that uses bubble sort' to sort an array of integers in memory. Your function, called bubble, should take two inputs:

$$a pointer to an array of integers in memory

$$the number of integers in the array to be sorted

bubble has no return value, but after execution, the integers in the array should be rearranged to be ordered from smallest to largest.