MIPS skeleton program

This is a simple MIPS skeleton program that demonstrates some simple MIPS instructions and .data & .text segments. The code is fully documented.

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

# Simple MIPS skeleton program: simple instructions, .data & .text #

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

# Declare main as a global function: 

# .globl is an assembler directive that tells the assembler that
# the main symbol will be accessible from outside the current file
# (that is, it can be referenced from other files)

.globl main

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

# All program code is placed after the .text assembler directive
.text


# The label 'main' represents the starting point
main:

    addi $t1, $t1, 1             # Load immediate value 1 into $t1 register

    li $t2, 0x25                 # Load immediate value 0x25 into $t2 register
    # The above is equivalent to:
    # ori $t2, $zero, 0x25
    
    lw $t3, value                # Load the word stored in value into $t3 = 0x26 = 38
    add $t4, $t2, $t3            # $t4 = $t2 + $t3 = 0x25 + 0x26 = 0x4b
    sub $t5, $t1, $t3            # $t5 = $t1 - $t3 = 1 - 0x26 = 0xffffffdb = -37
    sw $t5, Z                    # Store the answer in Z (declared at the bottom)  

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

    # Exit the program by means of a syscall.
    # There are many syscalls - pick the desired one
    # by placing its code in $v0. The code for exit is "10"
    
    li $v0, 10                   # Sets $v0 to "10" to select exit syscall
    syscall                      # Exit

    # The following instructions shoud NOT be executed due to the syscall 10 above!
    add $t5, $t5, $t5
    add $t5, $t5, $t5
    add $t5, $t5, $t5

# .... Memory structures are placed after the .data directive .... #

.data

# The .word assembler directive reserves space in memory for a single 4-byte word
# and assigns that memory location an initial value 

value:    .word 0x26
Z:        .word 0

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

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

Regards,

Antonis