# Typically saved in stack # $a0 - $a3 # Argument registers for passing in # arguments for subroutines # $v0 - $v1 # Return registers for returning # values to caller function # Types of load/store instructions la $t0, label # Copy the address of a value in # memory specified by the label # into register $t0 lw $t0, label # Copy a word value from memory lw $t1, 4 ( $s0 ) # Copy a word value from an address # stored in a register with an # offset of 4 bytes (addr + 4) lb $t2, label # Copy a byte value to the # lower order portion of # the register $t2 lb $t2, 0 ( $s0 ) # Copy a byte value from the source # address in $s0 with offset 0 # Same idea with 'lh' for halfwords sw $t0, label # Store word value into # memory address mapped by label sw $t0, 8 ( $s0 ) # Store word value into address # specified in $s0 and offset of # 8 bytes # Same idea using 'sb' and 'sh' for bytes and halfwords.
Beq mips maximum jummp distance code#
globl _main # Declares an instruction label as # global, making it accessible to # other files _main: # MIPS programs execute # instructions sequentially, where # the code under this label will be # executed first # Let's print "hello world" la $a0, hello_world # Load address of string stored # in memory li $v0, 4 # Load the syscall value (number # indicating which syscall to make) syscall # Perform the specified syscall # with the given argument ($a0) # Registers (used to hold data during program execution) # $t0 - $t9 # Temporary registers used for # intermediate calculations inside # subroutines (not saved across # function calls) # $s0 - $s7 # Saved registers where values are # saved across subroutine calls. text # Section that contains # instructions and program logic. (.align 2 # represents word alignment since # 2^2 = 4 bytes). align 2 # Memory alignment of data, where # number indicates byte alignment # in powers of 2. space 60 # Allocates space in the RAM # (not cleared to 0) # Datatype sizes _byte. byte ' a ', ' b ' # Array of chars (1 byte each) buffer. word 1, 2, 3, 4, 5 # Array of words arr2. word 42 # Integers are referred to as words # (32-bit value) arr1. asciiz "Hello World\n" # Declare a null terminated string num1. type value(s) ) form of declaration hello_world. data # Section where data is stored in memory (allocated in RAM), similar to # variables in higher-level languages # Declarations follow a ( label. # Comments are denoted with a '#' # Everything that occurs after a '#' will be ignored by the assembler's lexer.
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