li $a0, 0xace20ad
jal printhex
jal newline
li $a0, 0xFEEDFACE
jal printhex
jal newline
li $a0, 165 
jal printhex
jal newline
li $v0, 10
syscall

newline:
li $a0,10
li $v0,11
syscall
jr $ra

printhex:
add $sp,$sp,-8
sw $ra,0($sp)
sw $s0,4($sp)
and $s0,$a0,15 # last 4 bits (1 hex digit)
# switch from using $a0 for n to using it for rest
srl $a0,$a0,4 # rest of the bits (or hex digits)
beq $a0,$zero,printLastDigit
jal printhex
printLastDigit:
slti $t4,$s0,10
# switch from using $a0 for rest to using it for char
beq $t4,$zero,letter
add $a0,$s0,48
j printIt
letter:
add $a0,$s0,55
printIt:
li $v0,11
syscall
lw $ra,0($sp)
lw $s0,4($sp)
add $sp,$sp,8
jr $ra