Absolute value of the diferrence of two numbers

This is a sample MIPS assembler code to read two 32-bit numbers from memory and calculate the absolute value of their diferrence (ie |B-A|), store the result into memory and, finally, print it. The code is fully commented.

Launch EzMIPS, copy the following MIPS code and paste it into EzMIPS, the MIPS assembler editor & simulator. Assemble, Run.

# ------------------------------------------------------------------------- #
# Reads word A from from word variable var01
# Reads word B from from word variable var02
# Caclculate |B-A| and store the result into word variable var03
# ------------------------------------------------------------------------- #

.data
var01: .word 116            # address =0x10010000
var02: .word 17             # address =0x10010004
var03: .word 00             # address =0x10010008

var04: .asciiz "|B-A| = "

# expected output:
# |B-A| = 99

# ......................................................................... #

.text

    la $t1, var01           # Load address of var01

    lw $a0, 0($t1)          # read A from var01 into register $a0
    lw $a1, 4($t1)          # read B from var02 into register $a1
                            # (var02 address = address of var01 + 4)

    sub $t4, $a1, $a0       # $t4 = $a1 - $a0
    bgez $t4, positive      # if $t4 >= 0, branch to ‘sw’ instruction
    sub $t4, $a0, $a1       # else, $t4 = $a0 - $a1

positive:
    sw $t4, 8($t1)          # store register $t4 value, |B-A|, into var03
                            # (var03 address = address of var01 + 8)
# ......................................................................... #
    
    # print "|B-A| = "
    la $a0, var04           # Load address of var04
    li $v0, 4               # syscall code for print string
    syscall                 # print it!

    # print integer result of |B-A|
    move $a0, $t4
    li $v0, 1               # syscall code for print integer
    syscall                 # print it!

# ------------------------------------------------------------------------- #

Please let me know of any suggestions or bugs regarding the code above.

Regards,

Antonis