MIPS Assembly Language Programming

5.9. TREESORT.ASM 87
39 input_loop:
40 li $v0, 5 # syscall 5 == read_int.
41 syscall
42 move $s1, $v0 # $s1 = read_int
43
44 beq $s1, $s2, end_input # if we read the sentinel, break.
45
46 # tree_insert (number, root);
47 move $a0, $s1 # number= $s1
48 move $a1, $s0 # root = $s0
49 jal tree_insert # call tree_insert.
50
51 b input_loop # repeat input loop.
52 end_input:
53
54 ## Step 3: print out the left and right subtrees.
55 lw $a0, 4($s0) # print the root’s left child.
56 jal tree_print
57
58 lw $a0, 8($s0) # print the root’s right child.
59 jal tree_print
60
61 b exit # exit.
62 ## end of main.
63
64 ## tree_node_create (val, left, right): make a new node with the given
65 ## val and left and right descendants.
66 ## Register usage:
67 ## $s0 - val
68 ## $s1 - left
69 ## $s2 - right
70 tree_node_create:
71 # set up the stack frame:
72 subu $sp, $sp, 32
73 sw $ra, 28($sp)
74 sw $fp, 24($sp)
75 sw $s0, 20($sp)
76 sw $s1, 16($sp)
77 sw $s2, 12($sp)
78 sw $s3, 8($sp)
79 addu $fp, $sp, 32
80 # grab the parameters:
81 move $s0, $a0 # $s0 = val
82 move $s1, $a1 # $s1 = left