COMB:
beqz $a1 CEXIT #r == 0, return 1
beq $a0 $a1 CEXIT #n == r, return 1
addi $sp $sp -12 #Store n, r, and the return address
sw $a0 0($sp)
sw $a1 4($sp)
sw $ra 8($sp)
addi $a0 $a0 -1 #n = n - 1
jal COMB #Comb(n-1, r)
move $t0 $v0 #Temporarily move the return from the call to $t0
lw $a0 0($sp) #Reload all variables from the stack
lw $a1 4($sp)
lw $ra 8($sp)
addi $sp $sp 12
addi $sp $sp -16 #Store n, r, the return address, and the return from the first call
sw $a0 0($sp)
sw $a1 4($sp)
sw $ra 8($sp)
sw $t0 12($sp)
addi $a0 $a0 -1 #n = n - 1
addi $a1 $a1 -1 #r = r - 1
jal COMB #Comb(n-1, r-1)
lw $a0 0($sp) #Reload all variables from the stack
lw $a1 4($sp)
lw $ra 8($sp)
lw $t0 12($sp)
addi $sp $sp 16
move $t1 $v0
add $v0 $t0 $t1 #Return Comb(n-1, r) + Comb(n-1, r-1)
jr $ra


CEXIT:
li $v0 1 #Return 1
jr $ra