I need help to get the input from the keypad using the in built MARS $($MIPS$)$ tool Digital lab sim. I cannot get my scan function working. Here is the skeleton code so far: $.$text # Start generating instructions

$.$globl start # This label should be globally known

start:

li $t$0,0$xFFFF$0010$ # Load location of number pad scan register $($aligned to word boundary$)$

li $t$1,0$xFFFF$0014$ # Load location of number pad value register

li $t$2,0$x$10010000$ # Load base memory address of input values array

li $t$3,0$xFFFF$0010$ # Load location of seven seg display $($aligned to word boundary$)$

li $t$4,0$x$10010010$ # Load base memory address of $7-$seg values array

li $a$0,0$xa # Initialise value to write to display

jal draw$\_$num # Call the draw$\_$num function using 'jump and link'

scan:

# Load the value of the number pad scan register into $t$5$

lw $t$5,0($$t$0)$

decode$\_$input:

draw$\_$num:

add $t$5,$ $t$4,$ $a$0$ # Calculate address of element in array to access

lbu $t$6,0($$t$5)$ # Load decoder value byte from memory into $t$6$

sb $t$6,0($$t$3)$ # Write decoder value to seven segment display

jr $ra # Return from function using 'jump register' and $ra

end:

b end # End at infinite loop

$.$data # Items below this line will be stored in the

# $.$data section of memory

# Store the listed value$($s$)$ as $8-$bit values at the next available locations

$.$byte $0$x$11,0$x$21,0$x$41,0$x$81,0$x$12,0$x$22,0$x$42,0$x$82,0$x$14,0$x$24,0$x$44,0$x$84,0$x$18,0$x$28,0$x$48,0$x$88$

$.$byte $0$x$3$F$,0$x$06,0$x$5$B$,0$x$4$F$,0$x$66,0$x$6$D$,0$x$7$D$,0$x$07,0$x$7$F$,0$x$6$F$,0$x$77,0$x$7$C$,0$x$39,0$x$5$E$,0$x$79,0$x$71$