• MIPS Assembly
• register
• memory declaration
  • line label
    • inner label
• instruction format
  • R-type
  • I-type
• system call syscall
  • syscall code

MIPS Assembly

register

• $0: always 0
• $v0, $v1: expression evaluation and function return value
• $a0 ~ $a3: argument
• $t0 ~ $t9: temporary variable saved by caller
• $s0 ~ $s7: temporary variable saved by callee
• $gp: global area pointer
• $sp: stack pointer
• $fp: frame pointer
• $ra: return address

memory declaration

.data
var0: .word number0, number1, …
var1: .space number_of_bytes
var2: .byte character0, character1, …
var3: .asciiz string
var4: .float floating_point_number

.text
.align 2

.global main
main:       …
function0:  …

line label

label:  instruction0
        …

inner label

start with underscore to distinguish from function

instruction format

• Op: opcode
• Rs: source register

R-type

• Rt: the other source register
• Rd: destination register
• Sh: shift register
• Func: function code

I-type

• Rt: target register
• Immed: immediate value

system call syscall

1. load syscall code into $v0
2. put argument into $a0, $a1, $f12 (float)
3. syscall
4. return value in $v0, $f0 (float)

syscall code

• 1: print integer
• 2: print float
• 3: print double
• 4: print string
• 5: read integer
• 6: read float
• 7: read double
• 8: read string
  arguments: buffer, length
• 9: sbrk (malloc)
• 10: exit