User

Change the function time$2$string so that "DING" is shown instead of time, every minute at xx:$00.$ At xx:$01,$ time should be shown normally again. You are not allowed to change any other function or subroutine.

Example printout:

$59$:$57$

$59$:$58$

$59$:$59$

DING

$00$:$01$

$00$:$02$

$00$:$03$

$00$:$04$

$...$

The code is:

$.$global time$2$string, delay

$.$macro PUSH reg

addi $sp$,$$sp$,-4$

sw $\backslash$reg$,0($$sp$)$

$.$endm

$.$macro POP reg

lw $\backslash$reg$,0($$sp$)$

addi $sp$,$$sp$,4$

$.$endm

#

# Please add your own code below this line

#

$.$text

hexasc:

andi $v$0,$ $a$0,0$xF # Mask out all but the $4$ least significant bits

li $t$0,9$ # Compare with $9$ to determine if it's a digit or a letter

blt $v$0,$ $t$0,$ is$\_$digit # Branch if less than $9($it$\text{'}$s a digit$)$

addi $v$0,$ $v$0,7$ # Adjust for letters $($A starts at ASCII $65)$

is$\_$digit:

addi $v$0,$ $v$0,48$ # Adjust for ASCII digits $(0$ starts at ASCII $48)$

jr $ra # Return

delay:

# Save registers

addi $sp$,$ $sp$,-12$

sw $s$0,0($$sp$)$

sw $s$1,4($$sp$)$

sw $s$2,8($$sp$)$

# Initialize loop counter

li $s$0,4711$ # The constant $4711($adjust as needed$)$

# Outer loop: decrement ms

outer$\_$loop:

bnez $a$0,$ inner$\_$loop # if ms is not zero, go to inner loop

j end$\_$delay # if ms is zero, exit the delay

inner$\_$loop:

# Inner loop: decrement inner loop counter

bnez $s$0,$ inner$\_$loop # if counter is not zero, continue inner loop

addi $a$0,$ $a$0,-1$ # decrement ms

li $s$0,4711$ # reset inner loop counter

j outer$\_$loop # go to outer loop

# Restore registers and return

end$\_$delay:

lw $s$0,0($$sp$)$

lw $s$1,4($$sp$)$

lw $s$2,8($$sp$)$

addi $sp$,$ $sp$,12$

jr $ra

time$2$string:

PUSH $s$0$

PUSH $s$1$

PUSH $t$0$

move $s$0,$ $a$0$

move $s$1,$ $a$1$

# x$0$:$00$

andi $a$0,$ $s$1,0$xF$000$

srl $a$0,$ $a$0,12$

jal hexasc

sb $v$0,5($$s$0)$

# $0$x:$00$

andi $a$0,$ $s$1,0$xF$00$

srl $a$0,$ $a$0,8$

jal hexasc

sb $v$0,4($$s$0)$

# colon

li $a$0,0$x$3$A

sb $a$0,3($$s$0)$

# $00$:X$0$

andi $a$0,$ $s$1,0$xF$0$

srl $a$0,$ $a$0,4$

jal hexasc

sb $v$0,2($$s$0)$

# $00$:$0$X

andi $a$0,$ $s$1,0$xF

jal hexasc

sb $v$0,1($$s$0)$

# null$-$byte

li $a$0,0$x$00$

sb $a$0,0($$s$0)$

# Restore original s$1,$ s$2,$ and s$0$ values

POP $t$0$

POP $s$1$

POP $s$0$

jr $ra

nop