Monash University > School of Computer Science and Software Engineering > CSE1303 > Part B > Lectures > Lecture B09 notes

CSE1303 Computer Science
Semester 3 (summer), 2003
Part B
Lecture B09 notes: MIPS instructions

In this lecture

• MIPS instruction set
  • All instructions that MIPS computer is capable of performing
  • Arithmetic
    • add (addition)
    • sub (subtraction)
    • mul (multiplication)
    • div (division)
    • rem (modulus)
    • neg (negate)
  • Logic
    • and (bitwise AND)
    • or (bitwise OR)
    • xor (bitwise exclusive OR (XOR))
    • nor (bitwise not-OR (NOR))
    • not (bitwise NOT)
    • sll (shift left (logical))
    • srl (shift right (logical))
    • sra (shift right (arithmetic))
  • Data movement instructions
    • li (load immediate)
    • move (register-to-register copy)
  • Load/store instructions
    • lb (load byte from memory to register)
    • lh (load halfword from memory to register)
    • lw (load word from memory to register)
    • sb (store byte from register to memory)
    • sh (store halfword from register to memory)
    • sw (store word from register to memory)
    • la (compute address of location in memory)
  • Control transfer instructions
    • j (jump unconditionally)
    • jal (jump unconditionlly, remember return address)
    • jr (jump to address found in register)
    • jalr (jump to address found in register, remember return address)
    • beq (branch if equal)
    • bne (branch if not equal)
    • blt (branch if less than)
    • ble (branch if less than or equal)
    • bgt (branch if greater than)
    • bge (branch if greater than or equal)
  • Miscellaneous instructions
    • syscall (system call)
  • Immediate instructions
    • addi, andi, ori, xori
    • Others synthesized as pseudoinstructions
  • Pseudoinstructions
    • Also known as macro instructions
    • Instructions which are in fact implemented using other instructions instead
    • li, la, move, blt, ble, bgt, bge
  • Unsigned instructions
    • addu, subu, mulu, divu, bltu, bleu, bgtu, bgeu lbu, lhu
• Instruction formats
  • 32 bits
  • Encoding
    • R-format (usually 3 registers)
    • I-format (usually 2 registers and one immediate value)
    • J-format (one label)
• Extension
  • Zero extension: always fill with zero bits
  • Sign extension: always fill with copies of MSB

Listings

Slide 31

# Program to convert inches to millimetres.
# Integer approximation, multiply by 254/10.

        # Data used by the program
        .data
inch:   .word 42          # Allocate word, store value 42
mm:     .space 4          # Allocate word, value unimportant 

        # Program starts from label main.
        .text
main:   lw $t0, inch          # get inches into $t0
        mulu $t1, $t0, 254    # multiply...
        divu $t2, $t1, 10     # ...and divide
        sw $t2, mm            # store result in mm

        li $v0, 10            # system call 10...
        syscall               # ...exits simulation

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Last modified 2002-12-05