The following RISC$-$V assembly code calculates the trace $($sum of the diagonal$)$ of a square matrix. Fill in the gaps in the code. For registers. use the ABI name from the card given below $($second column$).$ For immediate operands, use decimal numbers, without leading zeros.

# sum of the diagonal of a square matrix

# matrix allocation in memory

$.$data

m: $.$word $1,2,3,4$

$.$word $5,6,7,8$

$.$word $-1,20,3,-4$

$.$word $9,2,8,5$

n: $.$word $4$

$.$text #

li a$0,0$ # a$0$ will store the sum

la s$0,$ m

lw s$1,$ n #this is a pseudoinstruction equivalent to la s$1,$ n; lw s$1,0($s$1)$

# calculate $4*$n in s$2$

slli s$2,\_\_,\_\_$# set s$2$ to point to the next row, same column of the matrix

addi s$2,\_\_,\_\_$ # now set s$2$ to point to the next element in the row; this will be on the diagonal

loop: lw t$0,\_\_($s$0)$ # load array element on the diagonal in t$0,$ start with m$(0,0)$

add $\_\_,\_\_,$ t$0$ # add the element to the sum

add $\_\_,$ s$0,\_\_$ # point to the next element in the diagonal

addi s$1,$ s$1,-1$ # decrement iterator

bne s$1,\_\_,$ loop #loop until you have gone through the entire array